Merge branch 'develop'

That's a big one, see the module-level comment for details.

.github/FUNDING.yml

@@ -0,0 +1 @@
+github: hakoerber

Cargo.lock

@@ -80,9 +80,9 @@ checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
 [[package]]
 name = "clap"
-version = "3.2.5"
+version = "3.2.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d53da17d37dba964b9b3ecb5c5a1f193a2762c700e6829201e645b9381c99dc7"
+checksum = "5b7b16274bb247b45177db843202209b12191b631a14a9d06e41b3777d6ecf14"
 dependencies = [
  "atty",
  "bitflags",
@@ -97,9 +97,9 @@ dependencies = [
 
 [[package]]
 name = "clap_derive"
-version = "3.2.5"
+version = "3.2.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c11d40217d16aee8508cc8e5fde8b4ff24639758608e5374e731b53f85749fb9"
+checksum = "759bf187376e1afa7b85b959e6a664a3e7a95203415dba952ad19139e798f902"
 dependencies = [
  "heck",
  "proc-macro-error",
@@ -110,9 +110,9 @@ dependencies = [
 
 [[package]]
 name = "clap_lex"
-version = "0.2.2"
+version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5538cd660450ebeb4234cfecf8f2284b844ffc4c50531e66d584ad5b91293613"
+checksum = "2850f2f5a82cbf437dd5af4d49848fbdfc27c157c3d010345776f952765261c5"
 dependencies = [
  "os_str_bytes",
 ]
@@ -155,12 +155,12 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-utils"
-version = "0.8.8"
+version = "0.8.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0bf124c720b7686e3c2663cf54062ab0f68a88af2fb6a030e87e30bf721fcb38"
+checksum = "7d82ee10ce34d7bc12c2122495e7593a9c41347ecdd64185af4ecf72cb1a7f83"
 dependencies = [
  "cfg-if",
- "lazy_static",
+ "once_cell",
 ]
 
 [[package]]
@@ -332,7 +332,7 @@ dependencies = [
 
 [[package]]
 name = "git-repo-manager"
-version = "0.7.3"
+version = "0.7.4"
 dependencies = [
  "clap",
  "comfy-table",
@@ -367,9 +367,9 @@ dependencies = [
 
 [[package]]
 name = "hashbrown"
-version = "0.11.2"
+version = "0.12.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ab5ef0d4909ef3724cc8cce6ccc8572c5c817592e9285f5464f8e86f8bd3726e"
+checksum = "db0d4cf898abf0081f964436dc980e96670a0f36863e4b83aaacdb65c9d7ccc3"
 
 [[package]]
 name = "heck"
@@ -410,9 +410,9 @@ dependencies = [
 
 [[package]]
 name = "indexmap"
-version = "1.8.2"
+version = "1.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e6012d540c5baa3589337a98ce73408de9b5a25ec9fc2c6fd6be8f0d39e0ca5a"
+checksum = "10a35a97730320ffe8e2d410b5d3b69279b98d2c14bdb8b70ea89ecf7888d41e"
 dependencies = [
  "autocfg",
  "hashbrown",
@@ -535,9 +535,9 @@ dependencies = [
 
 [[package]]
 name = "linked-hash-map"
-version = "0.5.4"
+version = "0.5.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7fb9b38af92608140b86b693604b9ffcc5824240a484d1ecd4795bacb2fe88f3"
+checksum = "0717cef1bc8b636c6e1c1bbdefc09e6322da8a9321966e8928ef80d20f7f770f"
 
 [[package]]
 name = "lock_api"
@@ -578,9 +578,9 @@ checksum = "2a60c7ce501c71e03a9c9c0d35b861413ae925bd979cc7a4e30d060069aaac8d"
 
 [[package]]
 name = "mio"
-version = "0.8.3"
+version = "0.8.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "713d550d9b44d89174e066b7a6217ae06234c10cb47819a88290d2b353c31799"
+checksum = "57ee1c23c7c63b0c9250c339ffdc69255f110b298b901b9f6c82547b7b87caaf"
 dependencies = [
  "libc",
  "log",
@@ -602,9 +602,9 @@ checksum = "ff011a302c396a5197692431fc1948019154afc178baf7d8e37367442a4601cf"
 
 [[package]]
 name = "openssl-src"
-version = "111.20.0+1.1.1o"
+version = "111.21.0+1.1.1p"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "92892c4f87d56e376e469ace79f1128fdaded07646ddf73aa0be4706ff712dec"
+checksum = "6d0a8313729211913936f1b95ca47a5fc7f2e04cd658c115388287f8a8361008"
 dependencies = [
  "cc",
 ]
@@ -746,18 +746,18 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.39"
+version = "1.0.40"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c54b25569025b7fc9651de43004ae593a75ad88543b17178aa5e1b9c4f15f56f"
+checksum = "dd96a1e8ed2596c337f8eae5f24924ec83f5ad5ab21ea8e455d3566c69fbcaf7"
 dependencies = [
  "unicode-ident",
 ]
 
 [[package]]
 name = "quote"
-version = "1.0.18"
+version = "1.0.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a1feb54ed693b93a84e14094943b84b7c4eae204c512b7ccb95ab0c66d278ad1"
+checksum = "3bcdf212e9776fbcb2d23ab029360416bb1706b1aea2d1a5ba002727cbcab804"
 dependencies = [
  "proc-macro2",
 ]
@@ -847,9 +847,9 @@ dependencies = [
 
 [[package]]
 name = "rustversion"
-version = "1.0.6"
+version = "1.0.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f2cc38e8fa666e2de3c4aba7edeb5ffc5246c1c2ed0e3d17e560aeeba736b23f"
+checksum = "a0a5f7c728f5d284929a1cccb5bc19884422bfe6ef4d6c409da2c41838983fcf"
 
 [[package]]
 name = "ryu"
@@ -895,9 +895,9 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.81"
+version = "1.0.82"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9b7ce2b32a1aed03c558dc61a5cd328f15aff2dbc17daad8fb8af04d2100e15c"
+checksum = "82c2c1fdcd807d1098552c5b9a36e425e42e9fbd7c6a37a8425f390f781f7fa7"
 dependencies = [
  "itoa",
  "ryu",
@@ -974,9 +974,9 @@ dependencies = [
 
 [[package]]
 name = "smallvec"
-version = "1.8.0"
+version = "1.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f2dd574626839106c320a323308629dcb1acfc96e32a8cba364ddc61ac23ee83"
+checksum = "cc88c725d61fc6c3132893370cac4a0200e3fedf5da8331c570664b1987f5ca2"
 
 [[package]]
 name = "socket2"
@@ -1002,9 +1002,9 @@ checksum = "063e6045c0e62079840579a7e47a355ae92f60eb74daaf156fb1e84ba164e63f"
 
 [[package]]
 name = "strum_macros"
-version = "0.24.1"
+version = "0.24.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9550962e7cf70d9980392878dfaf1dcc3ece024f4cf3bf3c46b978d0bad61d6c"
+checksum = "4faebde00e8ff94316c01800f9054fd2ba77d30d9e922541913051d1d978918b"
 dependencies = [
  "heck",
  "proc-macro2",
@@ -1015,9 +1015,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "1.0.96"
+version = "1.0.98"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0748dd251e24453cb8717f0354206b91557e4ec8703673a4b30208f2abaf1ebf"
+checksum = "c50aef8a904de4c23c788f104b7dddc7d6f79c647c7c8ce4cc8f73eb0ca773dd"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1129,9 +1129,9 @@ dependencies = [
 
 [[package]]
 name = "tracing-core"
-version = "0.1.27"
+version = "0.1.28"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7709595b8878a4965ce5e87ebf880a7d39c9afc6837721b21a5a816a8117d921"
+checksum = "7b7358be39f2f274f322d2aaed611acc57f382e8eb1e5b48cb9ae30933495ce7"
 dependencies = [
  "once_cell",
 ]
@@ -1160,9 +1160,9 @@ checksum = "5bd2fe26506023ed7b5e1e315add59d6f584c621d037f9368fea9cfb988f368c"
 
 [[package]]
 name = "unicode-normalization"
-version = "0.1.19"
+version = "0.1.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d54590932941a9e9266f0832deed84ebe1bf2e4c9e4a3554d393d18f5e854bf9"
+checksum = "81dee68f85cab8cf68dec42158baf3a79a1cdc065a8b103025965d6ccb7f6cbd"
 dependencies = [
  "tinyvec",
 ]

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "git-repo-manager"
-version = "0.7.3"
+version = "0.7.4"
 edition = "2021"
 
 authors = [
@@ -28,7 +28,7 @@ rust-version = "1.57"
 license = "GPL-3.0-only"
 
 [profile.e2e-tests]
-inherits = "release"
+inherits = "dev"
 
 [lib]
 name = "grm"
@@ -54,7 +54,7 @@ version = "=0.14.4"
 version = "=2.1.0"
 
 [dependencies.clap]
-version = "=3.2.5"
+version = "=3.2.7"
 features = ["derive", "cargo"]
 
 [dependencies.console]
@@ -70,7 +70,7 @@ version = "=6.0.0"
 version = "=0.8.24"
 
 [dependencies.serde_json]
-version = "=1.0.81"
+version = "=1.0.82"
 
 [dependencies.isahc]
 version = "=1.7.2"

Justfile

@@ -36,7 +36,7 @@ test-binary:
     env \
         GITHUB_API_BASEURL=http://rest:5000/github \
         GITLAB_API_BASEURL=http://rest:5000/gitlab \
-        cargo build --target {{static_target}} --profile e2e-tests --features=static-build
+        cargo build --profile e2e-tests --target {{static_target}} --features=static-build
 
 install:
     cargo install --path .
@@ -64,9 +64,9 @@ test-e2e +tests=".": test-binary
     && docker-compose build \
     && docker-compose run \
         --rm \
-        -v $PWD/../target/{{static_target}}/e2e-tests/grm:/grm \
+        -v $PWD/../target/x86_64-unknown-linux-musl/e2e-tests/grm:/grm \
             pytest \
-            "GRM_BINARY=/grm ALTERNATE_DOMAIN=alternate-rest python3 -m pytest -p no:cacheprovider --color=yes "$@"" \
+            "GRM_BINARY=/grm ALTERNATE_DOMAIN=alternate-rest python3 -m pytest --exitfirst -p no:cacheprovider --color=yes "$@"" \
     && docker-compose rm --stop -f
 
 update-dependencies: update-cargo-dependencies

e2e_tests/conftest.py

@@ -1,8 +1,14 @@
 import os
 
+from helpers import *
+
 
 def pytest_configure(config):
     os.environ["GIT_AUTHOR_NAME"] = "Example user"
     os.environ["GIT_AUTHOR_EMAIL"] = "user@example.com"
     os.environ["GIT_COMMITTER_NAME"] = "Example user"
     os.environ["GIT_COMMITTER_EMAIL"] = "user@example.com"
+
+
+def pytest_unconfigure(config):
+    pass

e2e_tests/docker/Dockerfile

@@ -1,7 +1,7 @@
 FROM docker.io/debian:11.3
 
 RUN apt-get update \
-    && apt-get install -y \
+    && apt-get install -y --no-install-recommends \
         python3-pytest \
         python3-toml \
         python3-git \

e2e_tests/helpers.py

@@ -5,12 +5,26 @@ import os.path
 import subprocess
 import tempfile
 import hashlib
+import shutil
+import inspect
 
 import git
 
 binary = os.environ["GRM_BINARY"]
 
 
+def funcname():
+    return inspect.stack()[1][3]
+
+
+def copytree(src, dest):
+    shutil.copytree(src, dest, dirs_exist_ok=True)
+
+
+def get_temporary_directory(dir=None):
+    return tempfile.TemporaryDirectory(dir=dir)
+
+
 def grm(args, cwd=None, is_invalid=False):
     cmd = subprocess.run([binary] + args, cwd=cwd, capture_output=True, text=True)
     if not is_invalid:
@@ -25,8 +39,12 @@ def grm(args, cwd=None, is_invalid=False):
 
 
 def shell(script):
-    script = "set -o errexit\nset -o nounset\n" + script
-    subprocess.run(["bash"], input=script, text=True, check=True)
+    script = "set -o errexit\nset -o nounset\nset -o pipefail\n" + script
+    cmd = subprocess.run(["bash"], input=script, text=True, capture_output=True)
+    if cmd.returncode != 0:
+        print(cmd.stdout)
+        print(cmd.stderr)
+    cmd.check_returncode()
 
 
 def checksum_directory(path):
@@ -112,78 +130,204 @@ def checksum_directory(path):
 class TempGitRepository:
     def __init__(self, dir=None):
         self.dir = dir
-        pass
 
     def __enter__(self):
-        self.tmpdir = tempfile.TemporaryDirectory(dir=self.dir)
-        self.remote_1_dir = tempfile.TemporaryDirectory()
-        self.remote_2_dir = tempfile.TemporaryDirectory()
-        shell(
-            f"""
+        self.tmpdir = get_temporary_directory(self.dir)
+        self.remote_1 = get_temporary_directory()
+        self.remote_2 = get_temporary_directory()
+        cmd = f"""
             cd {self.tmpdir.name}
-            git init
+            git -c init.defaultBranch=master init
             echo test > root-commit
             git add root-commit
             git commit -m "root-commit"
-            git remote add origin file://{self.remote_1_dir.name}
-            git remote add otherremote file://{self.remote_2_dir.name}
+            git remote add origin file://{self.remote_1.name}
+            git remote add otherremote file://{self.remote_2.name}
         """
-        )
+
+        shell(cmd)
         return self.tmpdir.name
 
     def __exit__(self, exc_type, exc_val, exc_tb):
-        del self.tmpdir
-        del self.remote_1_dir
-        del self.remote_2_dir
+        pass
+
+
+class TempGitRemote:
+    obj = {}
+
+    def __init__(self, tmpdir, remoteid=None):
+        self.tmpdir = tmpdir
+        self.remoteid = remoteid
+
+    @classmethod
+    def get(cls, cachekey=None, initfunc=None):
+        if cachekey is None:
+            tmpdir = get_temporary_directory()
+            shell(
+                f"""
+                cd {tmpdir.name}
+                git -c init.defaultBranch=master init --bare
+            """
+            )
+            newobj = cls(tmpdir)
+            remoteid = None
+            if initfunc is not None:
+                remoteid = newobj.init(initfunc)
+            newobj.remoteid = remoteid
+            return newobj, remoteid
+        else:
+            refresh = False
+            if cachekey not in cls.obj:
+                tmpdir = get_temporary_directory()
+                shell(
+                    f"""
+                    cd {tmpdir.name}
+                    git -c init.defaultBranch=master init --bare
+                """
+                )
+                newobj = cls(tmpdir)
+                remoteid = newobj.init(initfunc)
+                newobj.remoteid = remoteid
+                cls.obj[cachekey] = newobj
+            return cls.clone(cls.obj[cachekey])
+
+    @classmethod
+    def clone(cls, source):
+        new_remote = get_temporary_directory()
+        copytree(source.tmpdir.name, new_remote.name)
+        return cls(new_remote, source.remoteid), source.remoteid
+
+    def init(self, func):
+        return func(self.tmpdir.name)
+
+    def __enter__(self):
+        return self.tmpdir
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        pass
 
 
 class TempGitRepositoryWorktree:
-    def __init__(self):
-        pass
+    obj = {}
 
-    def __enter__(self):
-        self.tmpdir = tempfile.TemporaryDirectory()
-        self.remote_1_dir = tempfile.TemporaryDirectory()
-        self.remote_2_dir = tempfile.TemporaryDirectory()
+    def __init__(self, remotes, tmpdir, commit, remote1, remote2, remote1id, remote2id):
+        self.remotes = remotes
+        self.tmpdir = tmpdir
+        self.commit = commit
+        self.remote1 = remote1
+        self.remote2 = remote2
+        self.remote1id = remote1id
+        self.remote2id = remote2id
+
+    @classmethod
+    def get(cls, cachekey, branch=None, remotes=2, basedir=None, remote_setup=None):
+        if cachekey not in cls.obj:
+            tmpdir = get_temporary_directory()
             shell(
                 f"""
-            cd {self.remote_1_dir.name}
-            git init --bare
-        """
-        )
-        shell(
-            f"""
-            cd {self.remote_2_dir.name}
-            git init --bare
-        """
-        )
-        shell(
-            f"""
-            cd {self.tmpdir.name}
-            git init
+                cd {tmpdir.name}
+                git -c init.defaultBranch=master init
                 echo test > root-commit-in-worktree-1
                 git add root-commit-in-worktree-1
                 git commit -m "root-commit-in-worktree-1"
                 echo test > root-commit-in-worktree-2
                 git add root-commit-in-worktree-2
                 git commit -m "root-commit-in-worktree-2"
-            git remote add origin file://{self.remote_1_dir.name}
-            git remote add otherremote file://{self.remote_2_dir.name}
-            git push origin HEAD:master
+
                 git ls-files | xargs rm -rf
                 mv .git .git-main-working-tree
                 git --git-dir .git-main-working-tree config core.bare true
             """
             )
-        commit = git.Repo(
-            f"{self.tmpdir.name}/.git-main-working-tree"
-        ).head.commit.hexsha
-        return (self.tmpdir.name, commit)
+
+            repo = git.Repo(f"{tmpdir.name}/.git-main-working-tree")
+
+            commit = repo.head.commit.hexsha
+            if branch is not None:
+                repo.create_head(branch)
+
+            remote1 = None
+            remote2 = None
+            remote1id = None
+            remote2id = None
+
+            if remotes >= 1:
+                cachekeyremote, initfunc = (remote_setup or ((None, None),))[0]
+                remote1, remote1id = TempGitRemote.get(
+                    cachekey=cachekeyremote, initfunc=initfunc
+                )
+                remote1 = remote1
+                remote1id = remote1id
+                shell(
+                    f"""
+                    cd {tmpdir.name}
+                    git --git-dir .git-main-working-tree remote add origin file://{remote1.tmpdir.name}
+                """
+                )
+                repo.remotes.origin.fetch()
+                repo.remotes.origin.push("master")
+
+            if remotes >= 2:
+                cachekeyremote, initfunc = (remote_setup or (None, (None, None)))[1]
+                remote2, remote2id = TempGitRemote.get(
+                    cachekey=cachekeyremote, initfunc=initfunc
+                )
+                remote2 = remote2
+                remote2id = remote2id
+                shell(
+                    f"""
+                    cd {tmpdir.name}
+                    git --git-dir .git-main-working-tree remote add otherremote file://{remote2.tmpdir.name}
+                """
+                )
+                repo.remotes.otherremote.fetch()
+                repo.remotes.otherremote.push("master")
+
+            cls.obj[cachekey] = cls(
+                remotes, tmpdir, commit, remote1, remote2, remote1id, remote2id
+            )
+
+        return cls.clone(cls.obj[cachekey], remote_setup=remote_setup)
+
+    @classmethod
+    def clone(cls, source, remote_setup):
+        newdir = get_temporary_directory()
+
+        copytree(source.tmpdir.name, newdir.name)
+
+        remote1 = None
+        remote2 = None
+        remote1id = None
+        remote2id = None
+        repo = git.Repo(os.path.join(newdir.name, ".git-main-working-tree"))
+        if source.remotes >= 1:
+            cachekey, initfunc = (remote_setup or ((None, None),))[0]
+            remote1, remote1id = TempGitRemote.get(cachekey=cachekey, initfunc=initfunc)
+            if remote1id != source.remote1id:
+                repo.remotes.origin.fetch()
+                repo.remotes.origin.push("master")
+        if source.remotes >= 2:
+            cachekey, initfunc = (remote_setup or (None, (None, None)))[1]
+            remote2, remote2id = TempGitRemote.get(cachekey=cachekey, initfunc=initfunc)
+            if remote2id != source.remote2id:
+                repo.remotes.otherremote.fetch()
+                repo.remotes.otherremote.push("master")
+
+        return cls(
+            source.remotes,
+            newdir,
+            source.commit,
+            remote1,
+            remote2,
+            remote1id,
+            remote2id,
+        )
+
+    def __enter__(self):
+        return (self.tmpdir.name, self.commit)
 
     def __exit__(self, exc_type, exc_val, exc_tb):
-        del self.tmpdir
-        del self.remote_1_dir
-        del self.remote_2_dir
+        pass
 
 
 class RepoTree:
@@ -191,7 +335,7 @@ class RepoTree:
         pass
 
     def __enter__(self):
-        self.root = tempfile.TemporaryDirectory()
+        self.root = get_temporary_directory()
         self.config = tempfile.NamedTemporaryFile()
         with open(self.config.name, "w") as f:
             f.write(
@@ -222,7 +366,7 @@ class EmptyDir:
         pass
 
     def __enter__(self):
-        self.tmpdir = tempfile.TemporaryDirectory()
+        self.tmpdir = get_temporary_directory()
         return self.tmpdir.name
 
     def __exit__(self, exc_type, exc_val, exc_tb):
@@ -234,7 +378,7 @@ class NonGitDir:
         pass
 
     def __enter__(self):
-        self.tmpdir = tempfile.TemporaryDirectory()
+        self.tmpdir = get_temporary_directory()
         shell(
             f"""
             cd {self.tmpdir.name}
@@ -254,11 +398,11 @@ class TempGitFileRemote:
         pass
 
     def __enter__(self):
-        self.tmpdir = tempfile.TemporaryDirectory()
+        self.tmpdir = get_temporary_directory()
         shell(
             f"""
             cd {self.tmpdir.name}
-            git init
+            git -c init.defaultBranch=master init
             echo test > root-commit-in-remote-1
             git add root-commit-in-remote-1
             git commit -m "root-commit-in-remote-1"

e2e_tests/test_repos_find.py

@@ -73,7 +73,7 @@ def test_repos_find(configtype, default):
             mkdir repo1
             (
                 cd ./repo1
-                git init
+                git -c init.defaultBranch=master init
                 echo test > test
                 git add test
                 git commit -m "commit1"
@@ -83,7 +83,7 @@ def test_repos_find(configtype, default):
             mkdir repo2
             (
                 cd ./repo2
-                git init
+                git -c init.defaultBranch=master init
                 git checkout -b main
                 echo test > test
                 git add test
@@ -203,7 +203,7 @@ def test_repos_find_with_invalid_repo(configtype, default):
             mkdir repo1
             (
                 cd ./repo1
-                git init
+                git -c init.defaultBranch=master init
                 echo test > test
                 git add test
                 git commit -m "commit1"
@@ -213,7 +213,7 @@ def test_repos_find_with_invalid_repo(configtype, default):
             mkdir repo2
             (
                 cd ./repo2
-                git init
+                git -c init.defaultBranch=master init
                 git checkout -b main
                 echo test > test
                 git add test

e2e_tests/test_worktree_clean.py

@@ -6,7 +6,7 @@ from helpers import *
 
 
 def test_worktree_clean():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test", "--track", "origin/test"], cwd=base_dir)
         assert cmd.returncode == 0
         assert "test" in os.listdir(base_dir)
@@ -17,7 +17,7 @@ def test_worktree_clean():
 
 
 def test_worktree_clean_refusal_no_tracking_branch():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test"], cwd=base_dir)
         assert cmd.returncode == 0
 
@@ -31,7 +31,7 @@ def test_worktree_clean_refusal_no_tracking_branch():
 
 
 def test_worktree_clean_refusal_uncommited_changes_new_file():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test", "--track", "origin/test"], cwd=base_dir)
         assert cmd.returncode == 0
 
@@ -47,7 +47,7 @@ def test_worktree_clean_refusal_uncommited_changes_new_file():
 
 
 def test_worktree_clean_refusal_uncommited_changes_changed_file():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test", "--track", "origin/test"], cwd=base_dir)
         assert cmd.returncode == 0
 
@@ -63,7 +63,7 @@ def test_worktree_clean_refusal_uncommited_changes_changed_file():
 
 
 def test_worktree_clean_refusal_uncommited_changes_cleand_file():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test", "--track", "origin/test"], cwd=base_dir)
         assert cmd.returncode == 0
 
@@ -81,7 +81,7 @@ def test_worktree_clean_refusal_uncommited_changes_cleand_file():
 
 
 def test_worktree_clean_refusal_commited_changes():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test", "--track", "origin/test"], cwd=base_dir)
         assert cmd.returncode == 0
 
@@ -99,7 +99,7 @@ def test_worktree_clean_refusal_commited_changes():
 
 
 def test_worktree_clean_refusal_tracking_branch_mismatch():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test", "--track", "origin/test"], cwd=base_dir)
         assert cmd.returncode == 0
 
@@ -117,7 +117,7 @@ def test_worktree_clean_refusal_tracking_branch_mismatch():
 
 
 def test_worktree_clean_fail_from_subdir():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test"], cwd=base_dir)
         assert cmd.returncode == 0
 
@@ -148,7 +148,7 @@ def test_worktree_clean_non_git():
 def test_worktree_clean_configured_default_branch(
     configure_default_branch, branch_list_empty
 ):
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         if configure_default_branch:
             with open(os.path.join(base_dir, "grm.toml"), "w") as f:
                 if branch_list_empty:

e2e_tests/test_worktree_config_presistent_branch.py

@@ -6,7 +6,7 @@ from helpers import *
 
 
 def test_worktree_never_clean_persistent_branches():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         with open(os.path.join(base_dir, "grm.toml"), "w") as f:
             f.write(
                 """
@@ -33,7 +33,7 @@ def test_worktree_never_clean_persistent_branches():
 
 
 def test_worktree_clean_branch_merged_into_persistent():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         with open(os.path.join(base_dir, "grm.toml"), "w") as f:
             f.write(
                 """
@@ -72,7 +72,7 @@ def test_worktree_clean_branch_merged_into_persistent():
 
 
 def test_worktree_no_clean_unmerged_branch():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         with open(os.path.join(base_dir, "grm.toml"), "w") as f:
             f.write(
                 """
@@ -105,7 +105,7 @@ def test_worktree_no_clean_unmerged_branch():
 
 
 def test_worktree_delete_branch_merged_into_persistent():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         with open(os.path.join(base_dir, "grm.toml"), "w") as f:
             f.write(
                 """

e2e_tests/test_worktree_conversion.py

@@ -23,7 +23,7 @@ def test_convert():
 
 
 def test_convert_already_worktree():
-    with TempGitRepositoryWorktree() as (git_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (git_dir, _commit):
         before = checksum_directory(git_dir)
 
         cmd = grm(["wt", "convert"], cwd=git_dir)

e2e_tests/test_worktree_fetch.py

@@ -9,7 +9,7 @@ import git
 
 
 def test_worktree_fetch():
-    with TempGitRepositoryWorktree() as (base_dir, root_commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, root_commit):
         with TempGitFileRemote() as (remote_path, _remote_sha):
             shell(
                 f"""
@@ -56,7 +56,7 @@ def test_worktree_fetch():
 @pytest.mark.parametrize("has_changes", [True, False])
 @pytest.mark.parametrize("stash", [True, False])
 def test_worktree_pull(rebase, ffable, has_changes, stash):
-    with TempGitRepositoryWorktree() as (base_dir, root_commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, root_commit):
         with TempGitFileRemote() as (remote_path, _remote_sha):
             shell(
                 f"""

e2e_tests/test_worktree_rebase.py

@@ -14,7 +14,7 @@ import git
 @pytest.mark.parametrize("has_changes", [True, False])
 @pytest.mark.parametrize("stash", [True, False])
 def test_worktree_rebase(pull, rebase, ffable, has_changes, stash):
-    with TempGitRepositoryWorktree() as (base_dir, _root_commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _root_commit):
         with open(os.path.join(base_dir, "grm.toml"), "w") as f:
             f.write('persistent_branches = ["mybasebranch"]')
 

e2e_tests/test_worktree_status.py

@@ -9,7 +9,7 @@ import pytest
 
 @pytest.mark.parametrize("has_config", [True, False])
 def test_worktree_status(has_config):
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         if has_config:
             with open(os.path.join(base_dir, "grm.toml"), "w") as f:
                 f.write("")
@@ -24,7 +24,7 @@ def test_worktree_status(has_config):
 
 
 def test_worktree_status_fail_from_subdir():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test"], cwd=base_dir)
         assert cmd.returncode == 0
 
@@ -51,7 +51,7 @@ def test_worktree_status_non_git():
 
 
 def test_worktree_status_warn_with_non_worktree_dir():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test"], cwd=base_dir)
         assert cmd.returncode == 0
 

e2e_tests/test_worktrees.py

@@ -4,96 +4,565 @@ from helpers import *
 
 import git
 import pytest
+import datetime
 
 import os.path
 
 
+@pytest.mark.parametrize(
+    "config_setup",
+    (
+        (False, False, False),
+        (True, False, False),
+        (True, False, True),
+        (True, True, False),
+        (True, True, True),
+    ),
+)
+@pytest.mark.parametrize("explicit_notrack", [True, False])
+@pytest.mark.parametrize("explicit_track", [True, False])
+@pytest.mark.parametrize(
+    "local_branch_setup", ((False, False), (True, False), (True, True))
+)
 @pytest.mark.parametrize("remote_branch_already_exists", [True, False])
-@pytest.mark.parametrize("has_config", [True, False])
-@pytest.mark.parametrize("has_default", [True, False])
-@pytest.mark.parametrize("has_prefix", [True, False])
-def test_worktree_add_simple(
-    remote_branch_already_exists, has_config, has_default, has_prefix
+@pytest.mark.parametrize("remote_branch_with_prefix_already_exists", [True, False])
+@pytest.mark.parametrize(
+    "remote_setup",
+    (
+        (0, "origin", False),
+        (1, "origin", False),
+        (2, "origin", False),
+        (2, "otherremote", False),
+        (2, "origin", True),
+        (2, "otherremote", True),
+    ),
+)
+@pytest.mark.parametrize("track_differs_from_existing_branch_upstream", [True, False])
+@pytest.mark.parametrize("worktree_with_slash", [True, False])
+def test_worktree_add(
+    config_setup,
+    explicit_notrack,
+    explicit_track,
+    local_branch_setup,
+    remote_branch_already_exists,
+    remote_branch_with_prefix_already_exists,
+    remote_setup,
+    track_differs_from_existing_branch_upstream,
+    worktree_with_slash,
 ):
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
-        if has_config:
+    (remote_count, default_remote, remotes_differ) = remote_setup
+    (
+        config_enabled,
+        config_has_default_remote_prefix,
+        config_has_default_track_enabled,
+    ) = config_setup
+    (local_branch_exists, local_branch_has_tracking_branch) = local_branch_setup
+    has_remotes = True if remote_count > 0 else False
+
+    if worktree_with_slash:
+        worktree_name = "dir/nested/test"
+    else:
+        worktree_name = "test"
+
+    if track_differs_from_existing_branch_upstream:
+        explicit_track_branch_name = f"{default_remote}/somethingelse"
+    else:
+        explicit_track_branch_name = f"{default_remote}/{worktree_name}"
+
+    timestamp = datetime.datetime.now().replace(microsecond=0).isoformat()
+    # GitPython has some weird behaviour here. It is not possible to use kwargs
+    # to set the commit and author date.
+    #
+    # `committer_date=x` (which is documented) does not work, as `git commit`
+    # does not accept --committer-date
+    #
+    # `author_date=x` does not work, as it's now called --date in `git commit`
+    #
+    # `date=x` should work, but is refused by GitPython, as it does not know
+    # about the new behaviour in `git commit`
+    #
+    # Fortunately, there are env variables that control those timestamps.
+    os.environ["GIT_COMMITTER_DATE"] = str(timestamp)
+    os.environ["GIT_AUTHOR_DATE"] = str(timestamp)
+
+    def setup_remote1(directory):
+        if remote_branch_already_exists:
+            with tempfile.TemporaryDirectory() as cloned:
+                repo = git.Repo.clone_from(directory, cloned)
+                newfile = os.path.join(cloned, "change")
+                open(newfile, "w").close()
+                repo.index.add([newfile])
+                repo.index.commit("commit")
+                repo.remotes.origin.push(f"HEAD:{worktree_name}", force=True)
+
+        if remote_branch_with_prefix_already_exists:
+            with tempfile.TemporaryDirectory() as cloned:
+                repo = git.Repo.clone_from(directory, cloned)
+                newfile = os.path.join(cloned, "change2")
+                open(newfile, "w").close()
+                repo.index.add([newfile])
+                repo.index.commit("commit")
+                repo.remotes.origin.push(f"HEAD:myprefix/{worktree_name}", force=True)
+
+        return "_".join(
+            [
+                str(worktree_with_slash),
+                str(remote_branch_already_exists),
+                str(remote_branch_with_prefix_already_exists),
+                str(remotes_differ),
+            ]
+        )
+
+    def setup_remote2(directory):
+        if remote_branch_already_exists:
+            with tempfile.TemporaryDirectory() as cloned:
+                repo = git.Repo.clone_from(directory, cloned)
+                newfile = os.path.join(cloned, "change")
+                open(newfile, "w").close()
+                repo.index.add([newfile])
+                repo.index.commit("commit")
+                if remotes_differ:
+                    newfile = os.path.join(cloned, "change_on_second_remote")
+                    open(newfile, "w").close()
+                    repo.index.add([newfile])
+                    repo.index.commit("commit_on_second_remote")
+                repo.remotes.origin.push(f"HEAD:{worktree_name}", force=True)
+
+        if remote_branch_with_prefix_already_exists:
+            with tempfile.TemporaryDirectory() as cloned:
+                repo = git.Repo.clone_from(directory, cloned)
+                newfile = os.path.join(cloned, "change2")
+                open(newfile, "w").close()
+                repo.index.add([newfile])
+                repo.index.commit("commit")
+                if remotes_differ:
+                    newfile = os.path.join(cloned, "change_on_second_remote2")
+                    open(newfile, "w").close()
+                    repo.index.add([newfile])
+                    repo.index.commit("commit_on_second_remote2")
+                repo.remotes.origin.push(f"HEAD:myprefix/{worktree_name}", force=True)
+
+        return "_".join(
+            [
+                str(worktree_with_slash),
+                str(remote_branch_already_exists),
+                str(remote_branch_with_prefix_already_exists),
+                str(remotes_differ),
+            ]
+        )
+
+    cachefn = lambda nr: "_".join(
+        [
+            str(nr),
+            str(default_remote),
+            str(local_branch_exists),
+            str(remote_branch_already_exists),
+            str(remote_branch_with_prefix_already_exists),
+            str(remote_count),
+            str(remotes_differ),
+            str(worktree_name),
+        ]
+    )
+    remote1_cache_key = cachefn(1)
+    remote2_cache_key = cachefn(2)
+
+    cachekey = "_".join(
+        [
+            str(local_branch_exists),
+            str(local_branch_has_tracking_branch),
+            str(remote_branch_already_exists),
+            str(remote_branch_with_prefix_already_exists),
+            str(remote_count),
+            str(remotes_differ),
+            str(worktree_name),
+        ]
+    )
+
+    with TempGitRepositoryWorktree.get(
+        cachekey=cachekey,
+        branch=worktree_name if local_branch_exists else None,
+        remotes=remote_count,
+        remote_setup=[
+            [remote1_cache_key, setup_remote1],
+            [remote2_cache_key, setup_remote2],
+        ],
+    ) as (base_dir, initial_commit):
+        repo = git.Repo(os.path.join(base_dir, ".git-main-working-tree"))
+
+        if config_enabled:
             with open(os.path.join(base_dir, "grm.toml"), "w") as f:
                 f.write(
                     f"""
                         [track]
-                default = {str(has_default).lower()}
-                default_remote = "origin"
+                        default = {str(config_has_default_track_enabled).lower()}
+                        default_remote = "{default_remote}"
                         """
                 )
-                if has_prefix:
+
+                if config_has_default_remote_prefix:
                     f.write(
                         """
                     default_remote_prefix = "myprefix"
                     """
                     )
 
-        if remote_branch_already_exists:
-            shell(
-                f"""
-                cd {base_dir}
-                git --git-dir ./.git-main-working-tree worktree add tmp
-                (
-                    cd tmp
-                    touch change
-                    git add change
-                    git commit -m commit
-                    git push origin HEAD:test
-                    #git reset --hard 'HEAD@{1}'
-                    git branch -va
+        if local_branch_exists:
+            if has_remotes and local_branch_has_tracking_branch:
+                origin = repo.remote(default_remote)
+                if remote_count >= 2:
+                    otherremote = repo.remote("otherremote")
+                br = list(filter(lambda x: x.name == worktree_name, repo.branches))[0]
+                assert os.path.exists(base_dir)
+                if track_differs_from_existing_branch_upstream:
+                    origin.push(
+                        f"{worktree_name}:someothername", force=True, set_upstream=True
                     )
-                git --git-dir ./.git-main-working-tree worktree remove tmp
-            """
+                    if remote_count >= 2:
+                        otherremote.push(
+                            f"{worktree_name}:someothername",
+                            force=True,
+                            set_upstream=True,
                         )
-        cmd = grm(["wt", "add", "test"], cwd=base_dir)
+                    br.set_tracking_branch(
+                        list(
+                            filter(
+                                lambda x: x.remote_head == "someothername", origin.refs
+                            )
+                        )[0]
+                    )
+                else:
+                    origin.push(
+                        f"{worktree_name}:{worktree_name}",
+                        force=True,
+                        set_upstream=True,
+                    )
+                    if remote_count >= 2:
+                        otherremote.push(
+                            f"{worktree_name}:{worktree_name}",
+                            force=True,
+                            set_upstream=True,
+                        )
+                    br.set_tracking_branch(
+                        list(
+                            filter(
+                                lambda x: x.remote_head == worktree_name, origin.refs
+                            )
+                        )[0]
+                    )
+
+        args = ["wt", "add", worktree_name]
+        if explicit_track:
+            args.extend(["--track", explicit_track_branch_name])
+        if explicit_notrack:
+            args.extend(["--no-track"])
+        cmd = grm(args, cwd=base_dir)
+        if explicit_track and not explicit_notrack and not has_remotes:
+            assert cmd.returncode != 0
+            assert f'remote "{default_remote}" not found' in cmd.stderr.lower()
+            return
         assert cmd.returncode == 0
 
+        assert len(cmd.stdout.strip().split("\n")) == 1
+        assert f"worktree {worktree_name} created" in cmd.stdout.lower()
+
+        def check_deviation_error(base):
+            if (
+                not local_branch_exists
+                and (explicit_notrack or (not explicit_notrack and not explicit_track))
+                and (
+                    remote_branch_already_exists
+                    or (
+                        config_enabled
+                        and config_has_default_remote_prefix
+                        and remote_branch_with_prefix_already_exists
+                    )
+                )
+                and remote_count >= 2
+                and remotes_differ
+            ):
+                assert (
+                    f"branch exists on multiple remotes, but they deviate"
+                    in cmd.stderr.lower()
+                )
+                assert len(cmd.stderr.strip().split("\n")) == base + 1
+            else:
+                if base == 0:
+                    assert len(cmd.stderr) == base
+                else:
+                    assert len(cmd.stderr.strip().split("\n")) == base
+
+        if explicit_track and explicit_notrack:
+            assert "--track will be ignored" in cmd.stderr.lower()
+            check_deviation_error(1)
+        else:
+            check_deviation_error(0)
+
         files = os.listdir(base_dir)
-        if has_config is True:
+        if config_enabled is True:
+            if worktree_with_slash:
+                assert set(files) == {".git-main-working-tree", "grm.toml", "dir"}
+            else:
+                assert set(files) == {".git-main-working-tree", "grm.toml", "test"}
             assert len(files) == 3
+            if worktree_with_slash:
+                assert set(files) == {".git-main-working-tree", "grm.toml", "dir"}
+                assert set(os.listdir(os.path.join(base_dir, "dir"))) == {"nested"}
+                assert set(os.listdir(os.path.join(base_dir, "dir/nested"))) == {"test"}
+            else:
                 assert set(files) == {".git-main-working-tree", "grm.toml", "test"}
         else:
             assert len(files) == 2
+            if worktree_with_slash:
+                assert set(files) == {".git-main-working-tree", "dir"}
+                assert set(os.listdir(os.path.join(base_dir, "dir"))) == {"nested"}
+                assert set(os.listdir(os.path.join(base_dir, "dir/nested"))) == {"test"}
+            else:
                 assert set(files) == {".git-main-working-tree", "test"}
 
-        repo = git.Repo(os.path.join(base_dir, "test"))
+        repo = git.Repo(os.path.join(base_dir, worktree_name))
         assert not repo.bare
-        assert not repo.is_dirty()
-        if has_config and has_default:
-            if has_prefix and not remote_branch_already_exists:
+        # assert not repo.is_dirty()
+        assert str(repo.head.ref) == worktree_name
+
+        local_commit = repo.head.commit.hexsha
+
+        if not has_remotes:
+            assert local_commit == initial_commit
+        elif local_branch_exists:
+            assert local_commit == initial_commit
+        elif explicit_track and not explicit_notrack:
+            assert local_commit == repo.commit(explicit_track_branch_name).hexsha
+        elif explicit_notrack:
+            if config_enabled and config_has_default_remote_prefix:
+                if remote_branch_with_prefix_already_exists:
                     assert (
-                    str(repo.active_branch.tracking_branch()) == "origin/myprefix/test"
+                        local_commit
+                        == repo.commit(
+                            f"{default_remote}/myprefix/{worktree_name}"
+                        ).hexsha
+                    )
+                elif remote_branch_already_exists:
+                    assert (
+                        local_commit
+                        == repo.commit(f"{default_remote}/{worktree_name}").hexsha
                     )
                 else:
-                assert str(repo.active_branch.tracking_branch()) == "origin/test"
+                    assert local_commit == initial_commit
+            elif remote_count == 1:
+                if config_enabled and config_has_default_remote_prefix:
+                    if remote_branch_with_prefix_already_exists:
+                        assert (
+                            local_commit
+                            == repo.commit(
+                                f"{default_remote}/myprefix/{worktree_name}"
+                            ).hexsha
+                        )
+                    elif remote_branch_already_exists:
+                        assert (
+                            local_commit
+                            == repo.commit(f"{default_remote}/{worktree_name}").hexsha
+                        )
+                    else:
+                        assert local_commit == initial_commit
+                elif remote_branch_already_exists:
+                    assert (
+                        local_commit
+                        == repo.commit(f"{default_remote}/{worktree_name}").hexsha
+                    )
+                else:
+                    assert local_commit == initial_commit
+            elif remotes_differ:
+                if config_enabled:  # we have a default remote
+                    if (
+                        config_has_default_remote_prefix
+                        and remote_branch_with_prefix_already_exists
+                    ):
+                        assert (
+                            local_commit
+                            == repo.commit(
+                                f"{default_remote}/myprefix/{worktree_name}"
+                            ).hexsha
+                        )
+                    elif remote_branch_already_exists:
+                        assert (
+                            local_commit
+                            == repo.commit(f"{default_remote}/{worktree_name}").hexsha
+                        )
+                    else:
+                        assert local_commit == initial_commit
+                else:
+                    assert local_commit == initial_commit
+
+            else:
+                if config_enabled and config_has_default_remote_prefix:
+                    if remote_branch_with_prefix_already_exists:
+                        assert (
+                            local_commit
+                            == repo.commit(
+                                f"{default_remote}/myprefix/{worktree_name}"
+                            ).hexsha
+                        )
+                    elif remote_branch_already_exists:
+                        assert (
+                            local_commit
+                            == repo.commit(f"{default_remote}/{worktree_name}").hexsha
+                        )
+                    else:
+                        assert local_commit == initial_commit
+
+        elif config_enabled:
+            if not config_has_default_remote_prefix:
+                if config_has_default_track_enabled:
+                    assert (
+                        local_commit
+                        == repo.commit(f"{default_remote}/{worktree_name}").hexsha
+                    )
+                else:
+                    if remote_branch_already_exists:
+                        assert (
+                            local_commit
+                            == repo.commit(f"{default_remote}/{worktree_name}").hexsha
+                        )
+                    else:
+                        assert local_commit == initial_commit
+            else:
+                if remote_branch_with_prefix_already_exists:
+                    assert (
+                        local_commit
+                        == repo.commit(
+                            f"{default_remote}/myprefix/{worktree_name}"
+                        ).hexsha
+                    )
+                elif remote_branch_already_exists:
+                    assert (
+                        local_commit
+                        == repo.commit(f"{default_remote}/{worktree_name}").hexsha
+                    )
+                elif config_has_default_track_enabled:
+                    assert (
+                        local_commit
+                        == repo.commit(
+                            f"{default_remote}/myprefix/{worktree_name}"
+                        ).hexsha
+                    )
+                else:
+                    assert local_commit == initial_commit
+        elif remote_branch_already_exists and not remotes_differ:
+            assert (
+                local_commit == repo.commit(f"{default_remote}/{worktree_name}").hexsha
+            )
+        else:
+            assert local_commit == initial_commit
+
+        # Check whether tracking is ok
+        if not has_remotes:
+            assert repo.active_branch.tracking_branch() is None
+        elif explicit_notrack:
+            if local_branch_exists and local_branch_has_tracking_branch:
+                if track_differs_from_existing_branch_upstream:
+                    assert (
+                        str(repo.active_branch.tracking_branch())
+                        == f"{default_remote}/someothername"
+                    )
+                else:
+                    assert (
+                        str(repo.active_branch.tracking_branch())
+                        == f"{default_remote}/{worktree_name}"
+                    )
+            else:
+                assert repo.active_branch.tracking_branch() is None
+        elif explicit_track:
+            assert (
+                str(repo.active_branch.tracking_branch()) == explicit_track_branch_name
+            )
+        elif config_enabled and config_has_default_track_enabled:
+            if config_has_default_remote_prefix:
+                assert (
+                    str(repo.active_branch.tracking_branch())
+                    == f"{default_remote}/myprefix/{worktree_name}"
+                )
+            else:
+                assert (
+                    str(repo.active_branch.tracking_branch())
+                    == f"{default_remote}/{worktree_name}"
+                )
+        elif local_branch_exists and local_branch_has_tracking_branch:
+            if track_differs_from_existing_branch_upstream:
+                assert (
+                    str(repo.active_branch.tracking_branch())
+                    == f"{default_remote}/someothername"
+                )
+            else:
+                assert (
+                    str(repo.active_branch.tracking_branch())
+                    == f"{default_remote}/{worktree_name}"
+                )
         else:
             assert repo.active_branch.tracking_branch() is None
 
 
-def test_worktree_add_into_subdirectory():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
-        cmd = grm(["wt", "add", "dir/test"], cwd=base_dir)
+def test_worktree_add_invalid_name():
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
+        for worktree_name in [
+            "/absolute/path",
+            "trailingslash/",
+            "with spaces",
+            "with\t tabs",
+            "with\nnewline",
+        ]:
+            args = ["wt", "add", worktree_name]
+            cmd = grm(args, cwd=base_dir)
+            assert cmd.returncode != 0
+            assert not os.path.exists(worktree_name)
+            assert not os.path.exists(os.path.join(base_dir, worktree_name))
+            assert "invalid worktree name" in str(cmd.stderr.lower())
+
+
+def test_worktree_add_invalid_track():
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
+        for track in ["/absolute/path", "trailingslash/", "/"]:
+            args = ["wt", "add", "foo", "--track", track]
+            cmd = grm(args, cwd=base_dir)
+            assert cmd.returncode != 0
+            assert len(cmd.stderr.strip().split("\n")) == 1
+            assert not os.path.exists("foo")
+            assert not os.path.exists(os.path.join(base_dir, "foo"))
+            assert "tracking branch" in str(cmd.stderr.lower())
+
+
+@pytest.mark.parametrize("use_track", [True, False])
+@pytest.mark.parametrize("use_configuration", [True, False])
+@pytest.mark.parametrize("use_configuration_default", [True, False])
+def test_worktree_add_invalid_remote_name(
+    use_track, use_configuration, use_configuration_default
+):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
+        if use_configuration:
+            with open(os.path.join(base_dir, "grm.toml"), "w") as f:
+                f.write(
+                    f"""
+                [track]
+                default = {str(use_configuration_default).lower()}
+                default_remote = "thisremotedoesnotexist"
+                """
+                )
+
+        args = ["wt", "add", "foo"]
+        if use_track:
+            args.extend(["--track", "thisremotedoesnotexist/master"])
+
+        cmd = grm(args, cwd=base_dir)
+
+        if use_track or (use_configuration and use_configuration_default):
+            assert cmd.returncode != 0
+            assert "thisremotedoesnotexist" in cmd.stderr
+        else:
             assert cmd.returncode == 0
-
-        files = os.listdir(base_dir)
-        assert len(files) == 2
-        assert set(files) == {".git-main-working-tree", "dir"}
-
-        files = os.listdir(os.path.join(base_dir, "dir"))
-        assert set(files) == {"test"}
-
-        repo = git.Repo(os.path.join(base_dir, "dir", "test"))
-        assert not repo.bare
-        assert not repo.is_dirty()
-        assert repo.active_branch.tracking_branch() is None
+            assert len(cmd.stderr) == 0
 
 
 def test_worktree_add_into_invalid_subdirectory():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "/dir/test"], cwd=base_dir)
         assert cmd.returncode == 1
         assert "dir" not in os.listdir(base_dir)
@@ -104,177 +573,8 @@ def test_worktree_add_into_invalid_subdirectory():
         assert "dir" not in os.listdir(base_dir)
 
 
-@pytest.mark.parametrize("remote_branch_already_exists", [True, False])
-@pytest.mark.parametrize("has_config", [True, False])
-@pytest.mark.parametrize("has_default", [True, False])
-@pytest.mark.parametrize("has_prefix", [True, False])
-def test_worktree_add_with_tracking(
-    remote_branch_already_exists, has_config, has_default, has_prefix
-):
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
-        if has_config:
-            with open(os.path.join(base_dir, "grm.toml"), "w") as f:
-                f.write(
-                    f"""
-                [track]
-                default = {str(has_default).lower()}
-                default_remote = "origin"
-                """
-                )
-                if has_prefix:
-                    f.write(
-                        """
-                    default_remote_prefix = "myprefix"
-                    """
-                    )
-
-        if remote_branch_already_exists:
-            shell(
-                f"""
-                cd {base_dir}
-                git --git-dir ./.git-main-working-tree worktree add tmp
-                (
-                    cd tmp
-                    touch change
-                    git add change
-                    git commit -m commit
-                    git push origin HEAD:test
-                    #git reset --hard 'HEAD@{1}'
-                    git branch -va
-                )
-                git --git-dir ./.git-main-working-tree worktree remove tmp
-            """
-            )
-        cmd = grm(["wt", "add", "test", "--track", "origin/test"], cwd=base_dir)
-        print(cmd.stderr)
-        assert cmd.returncode == 0
-
-        files = os.listdir(base_dir)
-        if has_config is True:
-            assert len(files) == 3
-            assert set(files) == {".git-main-working-tree", "grm.toml", "test"}
-        else:
-            assert len(files) == 2
-            assert set(files) == {".git-main-working-tree", "test"}
-
-        repo = git.Repo(os.path.join(base_dir, "test"))
-        assert not repo.bare
-        assert not repo.is_dirty()
-        assert str(repo.active_branch) == "test"
-        assert str(repo.active_branch.tracking_branch()) == "origin/test"
-
-
-@pytest.mark.parametrize("has_config", [True, False])
-@pytest.mark.parametrize("has_default", [True, False])
-@pytest.mark.parametrize("has_prefix", [True, False])
-@pytest.mark.parametrize("track", [True, False])
-def test_worktree_add_with_explicit_no_tracking(
-    has_config, has_default, has_prefix, track
-):
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
-        if has_config:
-            with open(os.path.join(base_dir, "grm.toml"), "w") as f:
-                f.write(
-                    f"""
-                [track]
-                default = {str(has_default).lower()}
-                default_remote = "origin"
-                """
-                )
-                if has_prefix:
-                    f.write(
-                        """
-                    default_remote_prefix = "myprefix"
-                    """
-                    )
-        if track is True:
-            cmd = grm(
-                ["wt", "add", "test", "--track", "origin/test", "--no-track"],
-                cwd=base_dir,
-            )
-        else:
-            cmd = grm(["wt", "add", "test", "--no-track"], cwd=base_dir)
-        print(cmd.stderr)
-        assert cmd.returncode == 0
-
-        files = os.listdir(base_dir)
-        if has_config is True:
-            assert len(files) == 3
-            assert set(files) == {".git-main-working-tree", "grm.toml", "test"}
-        else:
-            assert len(files) == 2
-            assert set(files) == {".git-main-working-tree", "test"}
-
-        repo = git.Repo(os.path.join(base_dir, "test"))
-        assert not repo.bare
-        assert not repo.is_dirty()
-        assert str(repo.active_branch) == "test"
-        assert repo.active_branch.tracking_branch() is None
-
-
-@pytest.mark.parametrize("remote_branch_already_exists", [True, False])
-@pytest.mark.parametrize("has_default", [True, False])
-@pytest.mark.parametrize("has_prefix", [True, False])
-def test_worktree_add_with_config(
-    remote_branch_already_exists, has_default, has_prefix
-):
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
-        with open(os.path.join(base_dir, "grm.toml"), "w") as f:
-            f.write(
-                f"""
-            [track]
-            default = {str(has_default).lower()}
-            default_remote = "origin"
-            """
-            )
-            if has_prefix:
-                f.write(
-                    """
-                default_remote_prefix = "myprefix"
-                """
-                )
-        if remote_branch_already_exists:
-            shell(
-                f"""
-                cd {base_dir}
-                git --git-dir ./.git-main-working-tree worktree add tmp
-                (
-                    cd tmp
-                    touch change
-                    git add change
-                    git commit -m commit
-                    git push origin HEAD:test
-                    #git reset --hard 'HEAD@{1}'
-                    git branch -va
-                )
-                git --git-dir ./.git-main-working-tree worktree remove tmp
-            """
-            )
-        cmd = grm(["wt", "add", "test"], cwd=base_dir)
-        print(cmd.stderr)
-        assert cmd.returncode == 0
-
-        files = os.listdir(base_dir)
-        assert len(files) == 3
-        assert set(files) == {".git-main-working-tree", "grm.toml", "test"}
-
-        repo = git.Repo(os.path.join(base_dir, "test"))
-        assert not repo.bare
-        assert not repo.is_dirty()
-        assert str(repo.active_branch) == "test"
-        if has_default:
-            if has_prefix and not remote_branch_already_exists:
-                assert (
-                    str(repo.active_branch.tracking_branch()) == "origin/myprefix/test"
-                )
-            else:
-                assert str(repo.active_branch.tracking_branch()) == "origin/test"
-        else:
-            assert repo.active_branch.tracking_branch() is None
-
-
 def test_worktree_delete():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test", "--track", "origin/test"], cwd=base_dir)
         assert cmd.returncode == 0
         assert "test" in os.listdir(base_dir)
@@ -286,12 +586,35 @@ def test_worktree_delete():
         cmd = grm(["wt", "add", "check"], cwd=base_dir)
         assert cmd.returncode == 0
         repo = git.Repo(os.path.join(base_dir, ".git-main-working-tree"))
-        print(repo.branches)
         assert "test" not in [str(b) for b in repo.branches]
 
 
+@pytest.mark.parametrize("has_other_worktree", [True, False])
+def test_worktree_delete_in_subfolder(has_other_worktree):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
+        cmd = grm(["wt", "add", "dir/test", "--track", "origin/test"], cwd=base_dir)
+        assert cmd.returncode == 0
+        assert "dir" in os.listdir(base_dir)
+
+        if has_other_worktree is True:
+            cmd = grm(
+                ["wt", "add", "dir/test2", "--track", "origin/test"], cwd=base_dir
+            )
+            assert cmd.returncode == 0
+            assert {"test", "test2"} == set(os.listdir(os.path.join(base_dir, "dir")))
+        else:
+            assert {"test"} == set(os.listdir(os.path.join(base_dir, "dir")))
+
+        cmd = grm(["wt", "delete", "dir/test"], cwd=base_dir)
+        assert cmd.returncode == 0
+        if has_other_worktree is True:
+            assert {"test2"} == set(os.listdir(os.path.join(base_dir, "dir")))
+        else:
+            assert "dir" not in os.listdir(base_dir)
+
+
 def test_worktree_delete_refusal_no_tracking_branch():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test"], cwd=base_dir)
         assert cmd.returncode == 0
 
@@ -307,7 +630,7 @@ def test_worktree_delete_refusal_no_tracking_branch():
 
 
 def test_worktree_delete_refusal_uncommited_changes_new_file():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test", "--track", "origin/test"], cwd=base_dir)
         assert cmd.returncode == 0
 
@@ -325,7 +648,7 @@ def test_worktree_delete_refusal_uncommited_changes_new_file():
 
 
 def test_worktree_delete_refusal_uncommited_changes_changed_file():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test", "--track", "origin/test"], cwd=base_dir)
         assert cmd.returncode == 0
 
@@ -343,7 +666,7 @@ def test_worktree_delete_refusal_uncommited_changes_changed_file():
 
 
 def test_worktree_delete_refusal_uncommited_changes_deleted_file():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test", "--track", "origin/test"], cwd=base_dir)
         assert cmd.returncode == 0
 
@@ -363,7 +686,7 @@ def test_worktree_delete_refusal_uncommited_changes_deleted_file():
 
 
 def test_worktree_delete_refusal_commited_changes():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test", "--track", "origin/test"], cwd=base_dir)
         assert cmd.returncode == 0
 
@@ -383,7 +706,7 @@ def test_worktree_delete_refusal_commited_changes():
 
 
 def test_worktree_delete_refusal_tracking_branch_mismatch():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test", "--track", "origin/test"], cwd=base_dir)
         assert cmd.returncode == 0
 
@@ -403,7 +726,7 @@ def test_worktree_delete_refusal_tracking_branch_mismatch():
 
 
 def test_worktree_delete_force_refusal():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test"], cwd=base_dir)
         assert cmd.returncode == 0
 
@@ -413,7 +736,7 @@ def test_worktree_delete_force_refusal():
 
 
 def test_worktree_add_delete_add():
-    with TempGitRepositoryWorktree() as (base_dir, _commit):
+    with TempGitRepositoryWorktree.get(funcname()) as (base_dir, _commit):
         cmd = grm(["wt", "add", "test", "--track", "origin/test"], cwd=base_dir)
         assert cmd.returncode == 0
         assert "test" in os.listdir(base_dir)

src/grm/main.rs

@@ -1,3 +1,5 @@
+#![forbid(unsafe_code)]
+
 use std::path::Path;
 use std::process;
 
@@ -481,6 +483,9 @@ fn main() {
 
             match args.action {
                 cmd::WorktreeAction::Add(action_args) => {
+                    if action_args.track.is_some() && action_args.no_track {
+                        print_warning("You are using --track and --no-track at the same time. --track will be ignored");
+                    }
                     let track = match &action_args.track {
                         Some(branch) => {
                             let split = branch.split_once('/');
@@ -502,29 +507,20 @@ fn main() {
                         None => None,
                     };
 
-                    let mut name: &str = &action_args.name;
-                    let subdirectory;
-                    let split = name.split_once('/');
-                    match split {
-                        None => subdirectory = None,
-                        Some(split) => {
-                            if split.0.is_empty() || split.1.is_empty() {
-                                print_error("Worktree name cannot start or end with a slash");
-                                process::exit(1);
-                            } else {
-                                (subdirectory, name) = (Some(Path::new(split.0)), split.1);
-                            }
-                        }
-                    }
-
                     match worktree::add_worktree(
                         &cwd,
-                        name,
-                        subdirectory,
+                        &action_args.name,
                         track,
                         action_args.no_track,
                     ) {
-                        Ok(_) => print_success(&format!("Worktree {} created", &action_args.name)),
+                        Ok(warnings) => {
+                            if let Some(warnings) = warnings {
+                                for warning in warnings {
+                                    print_warning(&warning);
+                                }
+                            }
+                            print_success(&format!("Worktree {} created", &action_args.name));
+                        }
                         Err(error) => {
                             print_error(&format!("Error creating worktree: {}", error));
                             process::exit(1);
@@ -532,8 +528,6 @@ fn main() {
                     }
                 }
                 cmd::WorktreeAction::Delete(action_args) => {
-                    let worktree_dir = cwd.join(&action_args.name);
-
                     let worktree_config = match repo::read_worktree_root_config(&cwd) {
                         Ok(config) => config,
                         Err(error) => {
@@ -551,8 +545,9 @@ fn main() {
                     });
 
                     match repo.remove_worktree(
+                        &cwd,
                         &action_args.name,
-                        &worktree_dir,
+                        Path::new(&action_args.name),
                         action_args.force,
                         &worktree_config,
                     ) {

src/lib.rs

@@ -1,5 +1,6 @@
 #![feature(io_error_more)]
 #![feature(const_option_ext)]
+#![forbid(unsafe_code)]
 
 use std::path::Path;
 
@@ -13,8 +14,6 @@ pub mod table;
 pub mod tree;
 pub mod worktree;
 
-const BRANCH_NAMESPACE_SEPARATOR: &str = "/";
-
 /// Find all git repositories under root, recursively
 ///
 /// The bool in the return value specifies whether there is a repository

src/repo.rs

@@ -1153,18 +1153,21 @@ impl RepoHandle {
 
     pub fn remove_worktree(
         &self,
+        base_dir: &Path,
         name: &str,
         worktree_dir: &Path,
         force: bool,
         worktree_config: &Option<WorktreeRootConfig>,
     ) -> Result<(), WorktreeRemoveFailureReason> {
-        if !worktree_dir.exists() {
+        let fullpath = base_dir.join(worktree_dir);
+
+        if !fullpath.exists() {
             return Err(WorktreeRemoveFailureReason::Error(format!(
                 "{} does not exist",
                 name
             )));
         }
-        let worktree_repo = RepoHandle::open(worktree_dir, false).map_err(|error| {
+        let worktree_repo = RepoHandle::open(&fullpath, false).map_err(|error| {
             WorktreeRemoveFailureReason::Error(format!("Error opening repo: {}", error))
         })?;
 
@@ -1176,12 +1179,11 @@ impl RepoHandle {
             WorktreeRemoveFailureReason::Error(format!("Failed getting name of branch: {}", error))
         })?;
 
-        if branch_name != name
-            && !branch_name.ends_with(&format!("{}{}", super::BRANCH_NAMESPACE_SEPARATOR, name))
-        {
+        if branch_name != name {
             return Err(WorktreeRemoveFailureReason::Error(format!(
-                "Branch \"{}\" is checked out in worktree, this does not look correct",
-                &branch_name
+                "Branch \"{}\" is checked out in worktree \"{}\", this does not look correct",
+                &branch_name,
+                &worktree_dir.display(),
             )));
         }
 
@@ -1251,13 +1253,47 @@ impl RepoHandle {
             }
         }
 
-        if let Err(e) = std::fs::remove_dir_all(&worktree_dir) {
+        // worktree_dir is a relative path, starting from base_dir. We walk it
+        // upwards (from subdirectory to parent directories) and remove each
+        // component, in case it is empty. Only the leaf directory can be
+        // removed unconditionally (as it contains the worktree itself).
+        if let Err(e) = std::fs::remove_dir_all(&fullpath) {
             return Err(WorktreeRemoveFailureReason::Error(format!(
                 "Error deleting {}: {}",
                 &worktree_dir.display(),
                 e
             )));
         }
+
+        if let Some(current_dir) = worktree_dir.parent() {
+            for current_dir in current_dir.ancestors() {
+                let current_dir = base_dir.join(current_dir);
+                println!("deleting {}", current_dir.display());
+                if current_dir
+                    .read_dir()
+                    .map_err(|error| {
+                        WorktreeRemoveFailureReason::Error(format!(
+                            "Error reading {}: {}",
+                            &current_dir.display(),
+                            error
+                        ))
+                    })?
+                    .next()
+                    .is_none()
+                {
+                    if let Err(e) = std::fs::remove_dir_all(&current_dir) {
+                        return Err(WorktreeRemoveFailureReason::Error(format!(
+                            "Error deleting {}: {}",
+                            &worktree_dir.display(),
+                            e
+                        )));
+                    }
+                } else {
+                    break;
+                }
+            }
+        }
+
         self.prune_worktree(name)
             .map_err(WorktreeRemoveFailureReason::Error)?;
         branch
@@ -1310,7 +1346,13 @@ impl RepoHandle {
         {
             let repo_dir = &directory.join(&worktree.name());
             if repo_dir.exists() {
-                match self.remove_worktree(worktree.name(), repo_dir, false, &config) {
+                match self.remove_worktree(
+                    directory,
+                    worktree.name(),
+                    Path::new(worktree.name()),
+                    false,
+                    &config,
+                ) {
                     Ok(_) => print_success(&format!("Worktree {} deleted", &worktree.name())),
                     Err(error) => match error {
                         WorktreeRemoveFailureReason::Changes(changes) => {
@@ -1435,7 +1477,7 @@ impl<'a> Branch<'a> {
     }
 }
 
-impl Branch<'_> {
+impl<'a> Branch<'a> {
     pub fn commit(&self) -> Result<Commit, String> {
         Ok(Commit(
             self.0
@@ -1445,6 +1487,15 @@ impl Branch<'_> {
         ))
     }
 
+    pub fn commit_owned(self) -> Result<Commit<'a>, String> {
+        Ok(Commit(
+            self.0
+                .into_reference()
+                .peel_to_commit()
+                .map_err(convert_libgit2_error)?,
+        ))
+    }
+
     pub fn set_upstream(&mut self, remote_name: &str, branch_name: &str) -> Result<(), String> {
         self.0
             .set_upstream(Some(&format!("{}/{}", remote_name, branch_name)))

src/tree.rs

@@ -222,7 +222,7 @@ fn sync_repo(root_path: &Path, repo: &repo::Repo, init_worktree: bool) -> Result
     if newly_created && repo.worktree_setup && init_worktree {
         match repo_handle.default_branch() {
             Ok(branch) => {
-                worktree::add_worktree(&repo_path, &branch.name()?, None, None, false)?;
+                worktree::add_worktree(&repo_path, &branch.name()?, None, false)?;
             }
             Err(_error) => print_repo_error(
                 &repo.name,

src/worktree.rs

@@ -1,30 +1,584 @@
+//! This handles worktrees for repositories. Some considerations to take care
+//! of:
+//!
+//! * Which branch to check out / create
+//! * Which commit to check out
+//! * Whether to track a remote branch, and which
+//!
+//! There are a general rules. The main goal is to do the least surprising thing
+//! in each situation, and to never change existing setups (e.g. tracking,
+//! branch states) except when explicitly told to. In 99% of all cases, the
+//! workflow will be quite straightforward.
+//!
+//! * The name of the worktree (and therefore the path) is **always** the same
+//!   as the name of the branch.
+//! * Never modify existing local branches
+//! * Only modify tracking branches for existing local branches if explicitly
+//!   requested
+//! * By default, do not do remote operations. This means that we do no do any
+//!   tracking setup (but of course, the local branch can already have a
+//!   tracking branch set up, which will just be left alone)
+//! * Be quite lax with finding a remote tracking branch (as using an existing
+//!   branch is most likely preferred to creating a new branch)
+//!
+//! There are a few different options that can be given:
+//!
+//! * Explicit track (`--track`) and explicit no-track (`--no-track`)
+//! * A configuration may specify to enable tracking a remote branch by default
+//! * A configuration may specify a prefix for remote branches
+//!
+//! # How to handle the local branch?
+//!
+//! That one is easy: If a branch with the desired name already exists, all is
+//! well. If not, we create a new one.
+//!
+//! # Which commit should be checked out?
+//!
+//! The most imporant rule: If the local branch already existed, just leave it
+//! as it is. Only if a new branch is created do we need to answer the question
+//! which commit to set it to. Generally, we set the branch to whatever the
+//! "default" branch of the repository is (something like "main" or "master").
+//! But there are a few cases where we can use remote branches to make the
+//! result less surprising.
+//!
+//! First, if tracking is explicitly disabled, we still try to guess! But we
+//! *do* ignore `--track`, as this is how it's done everywhere else.
+//!
+//! As an example: If `origin/foobar` exists and we run `grm worktree add foobar
+//! --no-track`, we create a new worktree called `foobar` that's on the same
+//! state as `origin/foobar` (but we will not set up tracking, see below).
+//!
+//! If tracking is explicitly requested to a certain state, we use that remote
+//! branch. If it exists, easy. If not, no more guessing!
+//!
+//! Now, it's important to select the correct remote. In the easiest case, there
+//! is only one remote, so we just use that one. If there is more than one
+//! remote, we check whether there is a default remote configured via
+//! `track.default_remote`. If yes, we use that one. If not, we have to do the
+//! selection process below *for each of them*.  If only one of them returns
+//! some branch to track, we use that one. If more than one remote returns
+//! information, we only use it if it's identical for each. Otherwise we bail,
+//! as there is no point in guessing.
+//!
+//! The commit selection process looks like this:
+//!
+//! * If a prefix is specified in the configuration, we look for
+//!   `{remote}/{prefix}/{worktree_name}`
+//!
+//! * We look for `{remote}/{worktree_name}` (yes, this means that even when a
+//!   prefix is configured, we use a branch *without* a prefix if one with
+//!   prefix does not exist)
+//!
+//! Note that we may select different branches for different remotes when
+//! prefixes is used. If remote1 has a branch with a prefix and remote2 only has
+//! a branch *without* a prefix, we select them both when a prefix is used. This
+//! could lead to the following situation:
+//!
+//! * There is `origin/prefix/foobar` and `remote2/foobar`, with different
+//!   states
+//! * You set `track.default_prefix = "prefix"` (and no default remote!)
+//! * You run `grm worktree add `prefix/foobar`
+//! * Instead of just picking `origin/prefix/foobar`, grm will complain because
+//!   it also selected `remote2/foobar`.
+//!
+//! This is just emergent behaviour of the logic above. Fixing it would require
+//! additional logic for that edge case. I assume that it's just so rare to get
+//! that behaviour that it's acceptable for now.
+//!
+//! Now we either have a commit, we aborted, or we do not have commit. In the
+//! last case, as stated above, we check out the "default" branch.
+//!
+//! # The remote tracking branch
+//!
+//! First, the only remote operations we do is branch creation! It's
+//! unfortunately not possible to defer remote branch creation until the first
+//! `git push`, which would be ideal. The remote tracking branch has to already
+//! exist, so we have to do the equivalent of `git push --set-upstream` during
+//! worktree creation.
+//!
+//! Whether (and which) remote branch to track works like this:
+//!
+//! * If `--no-track` is given, we never track a remote branch, except when
+//!   branch already has a tracking branch. So we'd be done already!
+//!
+//! * If `--track` is given, we always track this branch, regardless of anything
+//!   else. If the branch exists, cool, otherwise we create it.
+//!
+//! If neither is given, we only set up tracking if requested in the
+//! configuration file (`track.default = true`)
+//!
+//! The rest of the process is similar to the commit selection above. The only
+//! difference is the remote selection.  If there is only one, we use it, as
+//! before. Otherwise, we try to use `default_remote` from the configuration, if
+//! available.  If not, we do not set up a remote tracking branch. It works like
+//! this:
+//!
+//! * If a prefix is specified in the configuration, we use
+//!   `{remote}/{prefix}/{worktree_name}`
+//!
+//! * If no prefix is specified in the configuration, we use
+//!   `{remote}/{worktree_name}`
+//!
+//! Now that we have a remote, we use the same process as above:
+//!
+//! * If a prefix is specified in the configuration, we use for
+//!   `{remote}/{prefix}/{worktree_name}`
+//! * We use for `{remote}/{worktree_name}`
+//!
+//! ---
+//!
+//! All this means that in some weird situation, you may end up with the state
+//! of a remote branch while not actually tracking that branch. This can only
+//! happen in repositories with more than one remote. Imagine the following:
+//!
+//! The repository has two remotes (`remote1` and `remote2`) which have the
+//! exact same remote state. But there is no `default_remote` in the
+//! configuration (or no configuration at all). There is a remote branch
+//! `foobar`. As both `remote1/foobar` and `remote2/foobar` as the same, the new
+//! worktree will use that as the state of the new branch. But as `grm` cannot
+//! tell which remote branch to track, it will not set up remote tracking. This
+//! behaviour may be a bit confusing, but first, there is no good way to resolve
+//! this, and second, the situation should be really rare (when having multiple
+//! remotes, you would generally have a `default_remote` configured).
+//!
+//! # Implementation
+//!
+//! To reduce the chance of bugs, the implementation uses the [typestate
+//! pattern](http://cliffle.com/blog/rust-typestate/). Here are the states we
+//! are moving through linearily:
+//!
+//! * Init
+//! * A local branch name is set
+//! * A local commit to set the new branch to is selected
+//! * A remote tracking branch is selected
+//! * The new branch is created with all the required settings
+//!
+//! Don't worry about the lifetime stuff: There is only one single lifetime, as
+//! everything (branches, commits) is derived from the single repo::Repo
+//! instance
+//!
+//! # Testing
+//!
+//! There are two types of input to the tests:
+//!
+//! 1) The parameters passed to `grm`, either via command line or via
+//!    configuration file
+//! 2) The circumstances in the repository and remotes
+//!
+//! ## Parameters
+//!
+//! * The name of the worktree
+//!   * Whether it contains slashes or not
+//!   * Whether it is invalid
+//! * `--track` and `--no-track`
+//! * Whether there is a configuration file and what it contains
+//!   * Whether `track.default` is enabled or disabled
+//!   * Whether `track.default_remote_prefix` is there or missing
+//!   * Whether `track.default_remote` is there or missing
+//!     * Whether that remote exists or not
+//!
+//! ## Situations
+//!
+//! ### The local branch
+//!
+//! * Whether the branch already exists
+//! * Whether the branch has a remote tracking branch and whether it differs
+//!   from the desired tracking branch (i.e. `--track` or config)
+//!
+//! ### Remotes
+//!
+//! * How many remotes there are, if any
+//! * If more than two remotes exist, whether their desired tracking branch
+//!   differs
+//!
+//! ### The remote tracking branch branch
+//!
+//! * Whether a remote branch with the same name as the worktree exists
+//! * Whether a remote branch with the same name as the worktree plus prefix
+//!   exists
+//!
+//! ## Outcomes
+//!
+//! We have to check the following afterwards:
+//!
+//! * Does the worktree exist in the correct location?
+//! * Does the local branch have the same name as the worktree?
+//! * Does the local branch have the correct commit?
+//! * Does the local branch track the correct remote branch?
+//! * Does that remote branch also exist?
+use std::cell::RefCell;
 use std::path::Path;
 
-use super::output::*;
+// use super::output::*;
 use super::repo;
 
 pub const GIT_MAIN_WORKTREE_DIRECTORY: &str = ".git-main-working-tree";
 
-// The logic about the base branch and the tracking branch is as follows:
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn invalid_worktree_names() {
+        assert!(add_worktree(Path::new("/tmp/"), "/leadingslash", None, false).is_err());
+        assert!(add_worktree(Path::new("/tmp/"), "trailingslash/", None, false).is_err());
+        assert!(add_worktree(Path::new("/tmp/"), "//", None, false).is_err());
+        assert!(add_worktree(Path::new("/tmp/"), "test//test", None, false).is_err());
+        assert!(add_worktree(Path::new("/tmp/"), "test test", None, false).is_err());
+        assert!(add_worktree(Path::new("/tmp/"), "test\ttest", None, false).is_err());
+    }
+}
+
+struct Init;
+
+struct WithLocalBranchName<'a> {
+    local_branch_name: String,
+    /// Outer option: Is there a computed value?
+    /// Inner option: Is there actually a branch?
+    ///
+    /// None => No computed value yet
+    /// Some(None) => No branch
+    /// Some(Some(_)) => Branch
+    local_branch: RefCell<Option<Option<repo::Branch<'a>>>>,
+}
+
+struct WithLocalTargetSelected<'a> {
+    local_branch_name: String,
+    local_branch: Option<repo::Branch<'a>>,
+    target_commit: Option<Box<repo::Commit<'a>>>,
+}
+
+struct WithRemoteTrackingBranch<'a> {
+    local_branch_name: String,
+    local_branch: Option<repo::Branch<'a>>,
+    target_commit: Option<Box<repo::Commit<'a>>>,
+    remote_tracking_branch: Option<(String, String)>,
+    prefix: Option<String>,
+}
+
+struct Worktree<'a, S: WorktreeState> {
+    repo: &'a repo::RepoHandle,
+    extra: S,
+}
+
+impl<'a> WithLocalBranchName<'a> {
+    fn new(name: String) -> Self {
+        Self {
+            local_branch_name: name,
+            local_branch: RefCell::new(None),
+        }
+    }
+}
+
+trait WorktreeState {}
+
+impl WorktreeState for Init {}
+impl<'a> WorktreeState for WithLocalBranchName<'a> {}
+impl<'a> WorktreeState for WithLocalTargetSelected<'a> {}
+impl<'a> WorktreeState for WithRemoteTrackingBranch<'a> {}
+
+impl<'a> Worktree<'a, Init> {
+    fn new(repo: &'a repo::RepoHandle) -> Self {
+        Self {
+            repo,
+            extra: Init {},
+        }
+    }
+
+    fn set_local_branch_name(self, name: &str) -> Worktree<'a, WithLocalBranchName<'a>> {
+        Worktree::<WithLocalBranchName> {
+            repo: self.repo,
+            extra: WithLocalBranchName::new(name.to_string()),
+        }
+    }
+}
+
+impl<'a, 'b> Worktree<'a, WithLocalBranchName<'b>>
+where
+    'a: 'b,
+{
+    fn check_local_branch(&self) {
+        let mut branchref = self.extra.local_branch.borrow_mut();
+        if branchref.is_none() {
+            let branch = self.repo.find_local_branch(&self.extra.local_branch_name);
+            *branchref = Some(if let Ok(branch) = branch {
+                Some(branch)
+            } else {
+                None
+            });
+        }
+    }
+
+    fn local_branch_already_exists(&self) -> bool {
+        if let Some(branch) = &*self.extra.local_branch.borrow() {
+            return branch.is_some();
+        }
+        self.check_local_branch();
+        // As we just called `check_local_branch`, we can be sure that
+        // `self.extra.local_branch` is set to some `Some` value
+        (*self.extra.local_branch.borrow())
+            .as_ref()
+            .unwrap()
+            .is_some()
+    }
+
+    fn select_commit(
+        self,
+        commit: Option<Box<repo::Commit<'b>>>,
+    ) -> Worktree<'a, WithLocalTargetSelected<'b>> {
+        self.check_local_branch();
+
+        Worktree::<'a, WithLocalTargetSelected> {
+            repo: self.repo,
+            extra: WithLocalTargetSelected::<'b> {
+                local_branch_name: self.extra.local_branch_name,
+                // As we just called `check_local_branch`, we can be sure that
+                // `self.extra.local_branch` is set to some `Some` value
+                local_branch: self.extra.local_branch.into_inner().unwrap(),
+                target_commit: commit,
+            },
+        }
+    }
+}
+
+impl<'a> Worktree<'a, WithLocalTargetSelected<'a>> {
+    fn set_remote_tracking_branch(
+        self,
+        branch: Option<(&str, &str)>,
+        prefix: Option<&str>,
+    ) -> Worktree<'a, WithRemoteTrackingBranch<'a>> {
+        Worktree::<WithRemoteTrackingBranch> {
+            repo: self.repo,
+            extra: WithRemoteTrackingBranch {
+                local_branch_name: self.extra.local_branch_name,
+                local_branch: self.extra.local_branch,
+                target_commit: self.extra.target_commit,
+                remote_tracking_branch: branch.map(|(s1, s2)| (s1.to_string(), s2.to_string())),
+                prefix: prefix.map(|prefix| prefix.to_string()),
+            },
+        }
+    }
+}
+
+impl<'a> Worktree<'a, WithRemoteTrackingBranch<'a>> {
+    fn create(self, directory: &Path) -> Result<Option<Vec<String>>, String> {
+        let mut warnings: Vec<String> = vec![];
+
+        let mut branch = if let Some(branch) = self.extra.local_branch {
+            branch
+        } else {
+            self.repo.create_branch(
+                &self.extra.local_branch_name,
+                // TECHDEBT
+                // We must not call this with `Some()` without a valid target.
+                // I'm sure this can be improved, just not sure how.
+                &*self.extra.target_commit.unwrap(),
+            )?
+        };
+
+        if let Some((remote_name, remote_branch_name)) = self.extra.remote_tracking_branch {
+            let remote_branch_with_prefix = if let Some(ref prefix) = self.extra.prefix {
+                if let Ok(remote_branch) = self
+                    .repo
+                    .find_remote_branch(&remote_name, &format!("{prefix}/{remote_branch_name}"))
+                {
+                    Some(remote_branch)
+                } else {
+                    None
+                }
+            } else {
+                None
+            };
+
+            let remote_branch_without_prefix = if let Ok(remote_branch) = self
+                .repo
+                .find_remote_branch(&remote_name, &remote_branch_name)
+            {
+                Some(remote_branch)
+            } else {
+                None
+            };
+
+            let remote_branch = if let Some(ref _prefix) = self.extra.prefix {
+                remote_branch_with_prefix
+            } else {
+                remote_branch_without_prefix
+            };
+
+            match remote_branch {
+                Some(remote_branch) => {
+                    if branch.commit()?.id().hex_string()
+                        != remote_branch.commit()?.id().hex_string()
+                    {
+                        warnings.push(format!("The local branch \"{}\" and the remote branch \"{}/{}\" differ. Make sure to push/pull afterwards!", &self.extra.local_branch_name, &remote_name, &remote_branch_name));
+                    }
+
+                    branch.set_upstream(&remote_name, &remote_branch.basename()?)?;
+                }
+                None => {
+                    let mut remote = match self.repo.find_remote(&remote_name)? {
+                        Some(remote) => remote,
+                        None => return Err(format!("Remote \"{remote_name}\" not found")),
+                    };
+
+                    if !remote.is_pushable()? {
+                        return Err(format!(
+                            "Cannot push to non-pushable remote \"{remote_name}\""
+                        ));
+                    }
+
+                    if let Some(prefix) = self.extra.prefix {
+                        remote.push(
+                            &self.extra.local_branch_name,
+                            &format!("{}/{}", prefix, remote_branch_name),
+                            self.repo,
+                        )?;
+
+                        branch.set_upstream(
+                            &remote_name,
+                            &format!("{}/{}", prefix, remote_branch_name),
+                        )?;
+                    } else {
+                        remote.push(
+                            &self.extra.local_branch_name,
+                            &remote_branch_name,
+                            self.repo,
+                        )?;
+
+                        branch.set_upstream(&remote_name, &remote_branch_name)?;
+                    }
+                }
+            }
+        }
+
+        // We have to create subdirectories first, otherwise adding the worktree
+        // will fail
+        if self.extra.local_branch_name.contains('/') {
+            let path = Path::new(&self.extra.local_branch_name);
+            if let Some(base) = path.parent() {
+                // This is a workaround of a bug in libgit2 (?)
                 //
-// * If a branch with the same name does not exist and no track is given, use the default
-//   branch
+                // When *not* doing this, we will receive an error from the `Repository::worktree()`
+                // like this:
                 //
-// * If a branch with the same name exists and no track is given, use that
+                // > failed to make directory '/{repo}/.git-main-working-tree/worktrees/dir/test
                 //
-// * If a branch with the same name does not exist and track is given, use the
-//   local branch that tracks that branch
+                // This is a discrepancy between the behaviour of libgit2 and the
+                // git CLI when creating worktrees with slashes:
                 //
-// * If a branch with the same name exists and track is given, use the locally
-//   existing branch. If the locally existing branch is not the local branch to
-//   the remote tracking branch, issue a warning
+                // The git CLI will create the worktree's configuration directory
+                // inside {git_dir}/worktrees/{last_path_component}. Look at this:
+                //
+                // ```
+                // $ git worktree add 1/2/3 -b 1/2/3
+                // $ ls .git/worktrees
+                // 3
+                // ```
+                //
+                // Interesting: When adding a worktree with a different name but the
+                // same final path component, git starts adding a counter suffix to
+                // the worktree directories:
+                //
+                // ```
+                // $ git worktree add 1/3/3 -b 1/3/3
+                // $ git worktree add 1/4/3 -b 1/4/3
+                // $ ls .git/worktrees
+                // 3
+                // 31
+                // 32
+                // ```
+                //
+                // I *guess* that the mapping back from the worktree directory under .git to the actual
+                // worktree directory is done via the `gitdir` file inside `.git/worktrees/{worktree}.
+                // This means that the actual directory would not matter. You can verify this by
+                // just renaming it:
+                //
+                // ```
+                // $ mv .git/worktrees/3 .git/worktrees/foobar
+                // $ git worktree list
+                // /tmp/       fcc8a2a7 [master]
+                // /tmp/1/2/3  fcc8a2a7 [1/2/3]
+                // /tmp/1/3/3  fcc8a2a7 [1/3/3]
+                // /tmp/1/4/3  fcc8a2a7 [1/4/3]
+                // ```
+                //
+                // => Still works
+                //
+                // Anyway, libgit2 does not do this: It tries to create the worktree
+                // directory inside .git with the exact name of the worktree, including
+                // any slashes. It should be this code:
+                //
+                // https://github.com/libgit2/libgit2/blob/f98dd5438f8d7bfd557b612fdf1605b1c3fb8eaf/src/libgit2/worktree.c#L346
+                //
+                // As a workaround, we can create the base directory manually for now.
+                //
+                // Tracking upstream issue: https://github.com/libgit2/libgit2/issues/6327
+                std::fs::create_dir_all(
+                    directory
+                        .join(GIT_MAIN_WORKTREE_DIRECTORY)
+                        .join("worktrees")
+                        .join(base),
+                )
+                .map_err(|error| error.to_string())?;
+                std::fs::create_dir_all(base).map_err(|error| error.to_string())?;
+            }
+        }
+
+        self.repo.new_worktree(
+            &self.extra.local_branch_name,
+            &directory.join(&self.extra.local_branch_name),
+            &branch,
+        )?;
+
+        Ok(if warnings.is_empty() {
+            None
+        } else {
+            Some(warnings)
+        })
+    }
+}
+
+/// A branch name must never start or end with a slash, and it cannot have two
+/// consecutive slashes
+fn validate_worktree_name(name: &str) -> Result<(), String> {
+    if name.starts_with('/') || name.ends_with('/') {
+        return Err(format!(
+            "Invalid worktree name: {}. It cannot start or end with a slash",
+            name
+        ));
+    }
+
+    if name.contains("//") {
+        return Err(format!(
+            "Invalid worktree name: {}. It cannot contain two consecutive slashes",
+            name
+        ));
+    }
+
+    if name.contains(char::is_whitespace) {
+        return Err(format!(
+            "Invalid worktree name: {}. It cannot contain whitespace",
+            name
+        ));
+    }
+
+    Ok(())
+}
+
+// TECHDEBT
+//
+// Instead of opening the repo & reading configuration inside the function, it
+// should be done by the caller and given as a parameter
 pub fn add_worktree(
     directory: &Path,
     name: &str,
-    subdirectory: Option<&Path>,
     track: Option<(&str, &str)>,
     no_track: bool,
-) -> Result<(), String> {
+) -> Result<Option<Vec<String>>, String> {
+    let mut warnings: Vec<String> = vec![];
+
+    validate_worktree_name(name)?;
+
     let repo = repo::RepoHandle::open(directory, true).map_err(|error| match error.kind {
         repo::RepoErrorKind::NotFound => {
             String::from("Current directory does not contain a worktree setup")
@@ -32,171 +586,195 @@ pub fn add_worktree(
         _ => format!("Error opening repo: {}", error),
     })?;
 
+    let remotes = &repo.remotes()?;
+
     let config = repo::read_worktree_root_config(directory)?;
 
     if repo.find_worktree(name).is_ok() {
         return Err(format!("Worktree {} already exists", &name));
     }
 
-    let path = match subdirectory {
-        Some(dir) => directory.join(dir).join(name),
-        None => directory.join(Path::new(name)),
-    };
+    let track_config = config.and_then(|config| config.track);
+    let prefix = track_config
+        .as_ref()
+        .and_then(|track| track.default_remote_prefix.as_ref());
+    let enable_tracking = track_config.as_ref().map_or(false, |track| track.default);
+    let default_remote = track_config
+        .as_ref()
+        .map(|track| track.default_remote.clone());
 
-    let mut remote_branch_exists = false;
+    // Note that we have to define all variables that borrow from `repo`
+    // *first*, otherwise we'll receive "borrowed value does not live long
+    // enough" errors. This is due to the `repo` reference inside `Worktree` that is
+    // passed through each state type.
+    //
+    // The `commit` variable will be dropped at the end of the scope, together with all
+    // worktree variables. It will be done in the opposite direction of delcaration (FILO).
+    //
+    // So if we define `commit` *after* the respective worktrees, it will be dropped first while
+    // still being borrowed by `Worktree`.
+    let default_branch_head = repo.default_branch()?.commit_owned()?;
 
-    let mut target_branch = match repo.find_local_branch(name) {
-        Ok(branchref) => {
-            if !no_track {
-                if let Some((remote_name, remote_branch_name)) = track {
-                    let remote_branch = repo.find_remote_branch(remote_name, remote_branch_name);
-                    if let Ok(remote_branch) = remote_branch {
-                        remote_branch_exists = true;
-                        if let Ok(local_upstream_branch) = branchref.upstream() {
-                            if remote_branch.name()? != local_upstream_branch.name()? {
-                                print_warning(&format!(
-                                    "You specified a tracking branch ({}/{}) for an existing branch ({}), but \
-                                    it differs from the current upstream ({}). Will keep current upstream"
-                                , remote_name, remote_branch_name, branchref.name()?, local_upstream_branch.name()?))
-                            }
-                        }
-                    }
-                }
-            }
-            branchref
-        }
-        Err(_) => {
-            let default_checkout = || repo.default_branch()?.to_commit();
+    let worktree = Worktree::<Init>::new(&repo).set_local_branch_name(name);
 
-            let checkout_commit;
-
-            if no_track {
-                checkout_commit = default_checkout()?;
+    let get_remote_head = |remote_name: &str,
+                           remote_branch_name: &str|
+     -> Result<Option<Box<repo::Commit>>, String> {
+        if let Ok(remote_branch) = repo.find_remote_branch(remote_name, remote_branch_name) {
+            Ok(Some(Box::new(remote_branch.commit_owned()?)))
         } else {
-                match track {
-                    Some((remote_name, remote_branch_name)) => {
-                        let remote_branch =
-                            repo.find_remote_branch(remote_name, remote_branch_name);
-                        match remote_branch {
-                            Ok(branch) => {
-                                remote_branch_exists = true;
-                                checkout_commit = branch.to_commit()?;
-                            }
-                            Err(_) => {
-                                remote_branch_exists = false;
-                                checkout_commit = default_checkout()?;
-                            }
-                        }
-                    }
-                    None => match &config {
-                        None => checkout_commit = default_checkout()?,
-                        Some(config) => match &config.track {
-                            None => checkout_commit = default_checkout()?,
-                            Some(track_config) => {
-                                if track_config.default {
-                                    let remote_branch =
-                                        repo.find_remote_branch(&track_config.default_remote, name);
-                                    match remote_branch {
-                                        Ok(branch) => {
-                                            remote_branch_exists = true;
-                                            checkout_commit = branch.to_commit()?;
-                                        }
-                                        Err(_) => {
-                                            checkout_commit = default_checkout()?;
-                                        }
-                                    }
-                                } else {
-                                    checkout_commit = default_checkout()?;
-                                }
-                            }
-                        },
-                    },
-                };
-            }
-
-            repo.create_branch(name, &checkout_commit)?
+            Ok(None)
         }
     };
 
-    fn push(
-        remote: &mut repo::RemoteHandle,
-        branch_name: &str,
-        remote_branch_name: &str,
-        repo: &repo::RepoHandle,
-    ) -> Result<(), String> {
-        if !remote.is_pushable()? {
-            return Err(format!(
-                "Cannot push to non-pushable remote {}",
-                remote.url()
-            ));
-        }
-        remote.push(branch_name, remote_branch_name, repo)
-    }
-
-    if !no_track {
-        if let Some((remote_name, remote_branch_name)) = track {
-            if remote_branch_exists {
-                target_branch.set_upstream(remote_name, remote_branch_name)?;
+    let worktree = if worktree.local_branch_already_exists() {
+        worktree.select_commit(None)
+    } else if let Some((remote_name, remote_branch_name)) = if no_track { None } else { track } {
+        if let Ok(remote_branch) = repo.find_remote_branch(remote_name, remote_branch_name) {
+            worktree.select_commit(Some(Box::new(remote_branch.commit_owned()?)))
         } else {
-                let mut remote = repo
-                    .find_remote(remote_name)
-                    .map_err(|error| format!("Error getting remote {}: {}", remote_name, error))?
-                    .ok_or_else(|| format!("Remote {} not found", remote_name))?;
-
-                push(
-                    &mut remote,
-                    &target_branch.name()?,
-                    remote_branch_name,
-                    &repo,
-                )?;
-
-                target_branch.set_upstream(remote_name, remote_branch_name)?;
+            worktree.select_commit(Some(Box::new(default_branch_head)))
         }
-        } else if let Some(config) = config {
-            if let Some(track_config) = config.track {
-                if track_config.default {
-                    let remote_name = track_config.default_remote;
-                    if remote_branch_exists {
-                        target_branch.set_upstream(&remote_name, name)?;
     } else {
-                        let remote_branch_name = match track_config.default_remote_prefix {
-                            Some(prefix) => {
-                                format!("{}{}{}", &prefix, super::BRANCH_NAMESPACE_SEPARATOR, &name)
+        match remotes.len() {
+            0 => worktree.select_commit(Some(Box::new(default_branch_head))),
+            1 => {
+                let remote_name = &remotes[0];
+                let commit: Option<Box<repo::Commit>> = ({
+                    if let Some(prefix) = prefix {
+                        get_remote_head(remote_name, &format!("{prefix}/{name}"))?
+                    } else {
+                        None
+                    }
+                })
+                .or(get_remote_head(remote_name, name)?)
+                .or_else(|| Some(Box::new(default_branch_head)));
+
+                worktree.select_commit(commit)
+            }
+            _ => {
+                let commit = if let Some(ref default_remote) = default_remote {
+                    if let Some(ref prefix) = prefix {
+                        if let Ok(remote_branch) = repo
+                            .find_remote_branch(default_remote, &format!("{prefix}/{name}"))
+                        {
+                            Some(Box::new(remote_branch.commit_owned()?))
+                        } else {
+                            None
+                        }
+                    } else {
+                        None
+                    }
+                    .or({
+                        if let Ok(remote_branch) =
+                            repo.find_remote_branch(default_remote, name)
+                        {
+                            Some(Box::new(remote_branch.commit_owned()?))
+                        } else {
+                            None
+                        }
+                    })
+                } else {
+                    None
+                }.or({
+                    let mut commits = vec![];
+                    for remote_name in remotes.iter() {
+                        let remote_head: Option<Box<repo::Commit>> = ({
+                            if let Some(ref prefix) = prefix {
+                                if let Ok(remote_branch) = repo.find_remote_branch(
+                                    remote_name,
+                                    &format!("{prefix}/{name}"),
+                                ) {
+                                    Some(Box::new(remote_branch.commit_owned()?))
+                                } else {
+                                    None
+                                }
+                            } else {
+                                None
+                            }
+                        })
+                        .or({
+                            if let Ok(remote_branch) =
+                                repo.find_remote_branch(remote_name, name)
+                            {
+                                Some(Box::new(remote_branch.commit_owned()?))
+                            } else {
+                                None
+                            }
+                        })
+                        .or(None);
+                        commits.push(remote_head);
+                    }
+
+                    let mut commits = commits
+                        .into_iter()
+                        .flatten()
+                        // have to collect first because the `flatten()` return
+                        // typedoes not implement `windows()`
+                        .collect::<Vec<Box<repo::Commit>>>();
+                    // `flatten()` takes care of `None` values here. If all
+                    // remotes return None for the branch, we do *not* abort, we
+                    // continue!
+                    if commits.is_empty() {
+                        Some(Box::new(default_branch_head))
+                    } else if commits.len() == 1 {
+                        Some(commits.swap_remove(0))
+                    } else if commits.windows(2).any(|window| {
+                        let c1 = &window[0];
+                        let c2 = &window[1];
+                        (*c1).id().hex_string() != (*c2).id().hex_string()
+                    }) {
+                        warnings.push(
+                            // TODO this should also include the branch
+                            // name. BUT: the branch name may be different
+                            // between the remotes. Let's just leave it
+                            // until I get around to fix that inconsistency
+                            // (see module-level doc about), which might be
+                            // never, as it's such a rare edge case.
+                            "Branch exists on multiple remotes, but they deviate. Selecting default branch instead".to_string()
+                        );
+                        Some(Box::new(default_branch_head))
+                    } else {
+                        Some(commits.swap_remove(0))
+                    }
+                });
+                worktree.select_commit(commit)
+            }
         }
-                            None => name.to_string(),
     };
 
-                        let mut remote = repo
-                            .find_remote(&remote_name)
-                            .map_err(|error| {
-                                format!("Error getting remote {}: {}", remote_name, error)
-                            })?
-                            .ok_or_else(|| format!("Remote {} not found", remote_name))?;
+    let worktree = if no_track {
+        worktree.set_remote_tracking_branch(None, prefix.map(|s| s.as_str()))
+    } else if let Some((remote_name, remote_branch_name)) = track {
+        worktree.set_remote_tracking_branch(
+            Some((remote_name, remote_branch_name)),
+            None, // Always disable prefixing when explicitly given --track
+        )
+    } else if !enable_tracking {
+        worktree.set_remote_tracking_branch(None, prefix.map(|s| s.as_str()))
+    } else {
+        match remotes.len() {
+            0 => worktree.set_remote_tracking_branch(None, prefix.map(|s| s.as_str())),
+            1 => worktree
+                .set_remote_tracking_branch(Some((&remotes[0], name)), prefix.map(|s| s.as_str())),
+            _ => {
+                if let Some(default_remote) = default_remote {
+                    worktree.set_remote_tracking_branch(
+                        Some((&default_remote, name)),
+                        prefix.map(|s| s.as_str()),
+                    )
+                } else {
+                    worktree.set_remote_tracking_branch(None, prefix.map(|s| s.as_str()))
+                }
+            }
+        }
+    };
 
-                        if !remote.is_pushable()? {
-                            return Err(format!(
-                                "Cannot push to non-pushable remote {}",
-                                remote.url()
-                            ));
-                        }
-                        push(
-                            &mut remote,
-                            &target_branch.name()?,
-                            &remote_branch_name,
-                            &repo,
-                        )?;
+    worktree.create(directory)?;
 
-                        target_branch.set_upstream(&remote_name, &remote_branch_name)?;
-                    }
-                }
-            }
-        }
-    }
-
-    if let Some(subdirectory) = subdirectory {
-        std::fs::create_dir_all(subdirectory).map_err(|error| error.to_string())?;
-    }
-    repo.new_worktree(name, &path, &target_branch)?;
-
-    Ok(())
+    Ok(if warnings.is_empty() {
+        None
+    } else {
+        Some(warnings)
+    })
 }