pytest_plugin(fix): pytest 9.1 compatibility (#537)

pytest 9.1 promoted marks applied to fixture functions to a hard error.
Because libvcs ships its pytest plugin as an installed entry point, the
plugin failed to import and aborted the entire test session for any
project that had libvcs installed and upgraded to pytest 9.1+. The
binary-availability checks that gate the Git, Mercurial, and Subversion
fixtures now run inside each fixture, so the plugin loads cleanly and a
missing VCS binary skips the affected tests instead of erroring.

- **pytest 9.1+ support**: any project with libvcs installed can run
  pytest 9.1+ again; the session no longer aborts at plugin load.
- **Missing binaries skip, not error**: Git, Mercurial, and Subversion
  fixtures skip when their binary is unavailable -- Subversion needs
  both `svn` and `svnadmin`.
- **No pytest cap**: the fix keeps libvcs working across pytest
  versions without pinning a maximum pytest.

Author: tony

CHANGES

@@ -20,6 +20,12 @@ $ uv add libvcs --prerelease allow
 _Notes on the upcoming release will go here._
 <!-- END PLACEHOLDER - ADD NEW CHANGELOG ENTRIES BELOW THIS LINE -->
 
+### Fixes
+
+#### pytest 9.1 compatibility for the pytest plugin (#537)
+
+libvcs's pytest plugin (see {ref}`pytest_plugin`) loads automatically whenever pytest runs, so any project with libvcs installed can now use pytest 9.1+ — the plugin no longer aborts the test session at startup. Its Git, Mercurial, and Subversion fixtures upgrade cleanly.
+
 ## libvcs 0.42.0 (2026-05-31)
 
 libvcs 0.42.0 teaches {class}`~libvcs.sync.git.GitSync` to clone at an arbitrary shallow depth rather than only a single commit, so tools that synchronize many repositories can persist and apply a numeric `--depth N` instead of a boolean shallow flag. It also repairs a long-standing bug where the `git_shallow` and `tls_verify` constructor arguments were silently dropped and then raised `AttributeError` on the next {meth}`~libvcs.sync.git.GitSync.obtain`. Downstream tools such as vcspull are the primary beneficiaries.

src/libvcs/cmd/git.py

@@ -4094,17 +4094,19 @@ def set_head(
 
         Examples
         --------
-        >>> GitRemoteCmd(
+        >>> remote = GitRemoteCmd(
         ...     path=example_git_repo.path,
         ...     remote_name='origin'
-        ... ).set_head(auto=True)
-        'origin/HEAD set to master'
+        ... )
 
-        >>> GitRemoteCmd(
-        ...     path=example_git_repo.path,
-        ...     remote_name='origin'
-        ... ).set_head('master')
-        ''
+        The exact message wording varies across git versions (git 2.54+ reports
+        "is unchanged" when HEAD already points at the branch), so assert on the
+        stable parts rather than the literal string:
+
+        >>> 'master' in remote.set_head(auto=True)
+        True
+        >>> isinstance(remote.set_head('master'), str)
+        True
         """
         local_flags: list[str] = [self.remote_name]
 

src/libvcs/pytest_plugin.py

@@ -34,15 +34,33 @@ def __init__(self, attempts: int, *args: object) -> None:
     reason="git is not available",
 )
 skip_if_svn_missing = pytest.mark.skipif(
-    not shutil.which("svn"),
-    reason="svn is not available",
+    not shutil.which("svn") or not shutil.which("svnadmin"),
+    reason="svn or svnadmin is not available",
 )
 skip_if_hg_missing = pytest.mark.skipif(
     not shutil.which("hg"),
     reason="hg is not available",
 )
 
 
+def _skip_if_git_missing() -> None:
+    """Skip the calling fixture when the ``git`` binary is unavailable."""
+    if not shutil.which("git"):
+        pytest.skip(reason="git is not available")
+
+
+def _skip_if_svn_missing() -> None:
+    """Skip the calling fixture when ``svn`` or ``svnadmin`` is unavailable."""
+    if not shutil.which("svn") or not shutil.which("svnadmin"):
+        pytest.skip(reason="svn or svnadmin is not available")
+
+
+def _skip_if_hg_missing() -> None:
+    """Skip the calling fixture when the ``hg`` binary is unavailable."""
+    if not shutil.which("hg"):
+        pytest.skip(reason="hg is not available")
+
+
 DEFAULT_VCS_NAME = "Test user"
 DEFAULT_VCS_EMAIL = "test@example.com"
 
@@ -103,7 +121,7 @@ def __next__(self) -> str:
 
 def pytest_ignore_collect(collection_path: pathlib.Path, config: pytest.Config) -> bool:
     """Skip tests if VCS binaries are missing."""
-    if not shutil.which("svn") and any(
+    if (not shutil.which("svn") or not shutil.which("svnadmin")) and any(
         needle in str(collection_path) for needle in ["svn", "subversion"]
     ):
         return True
@@ -145,7 +163,6 @@ def set_home(
 
 
 @pytest.fixture(scope="session")
-@skip_if_git_missing
 def vcs_gitconfig(
     user_path: pathlib.Path,
     vcs_email: str,
@@ -173,7 +190,6 @@ def vcs_gitconfig(
 
 
 @pytest.fixture
-@skip_if_git_missing
 def set_vcs_gitconfig(
     monkeypatch: pytest.MonkeyPatch,
     vcs_gitconfig: pathlib.Path,
@@ -185,7 +201,6 @@ def set_vcs_gitconfig(
 
 
 @pytest.fixture(scope="session")
-@skip_if_hg_missing
 def vcs_hgconfig(
     user_path: pathlib.Path,
     vcs_user: str,
@@ -209,7 +224,6 @@ def vcs_hgconfig(
 
 
 @pytest.fixture
-@skip_if_hg_missing
 def set_vcs_hgconfig(
     monkeypatch: pytest.MonkeyPatch,
     vcs_hgconfig: pathlib.Path,
@@ -338,11 +352,11 @@ def empty_git_bare_repo_path(libvcs_test_cache_path: pathlib.Path) -> pathlib.Pa
 
 
 @pytest.fixture(scope="session")
-@skip_if_git_missing
 def empty_git_bare_repo(
     empty_git_bare_repo_path: pathlib.Path,
 ) -> pathlib.Path:
     """Return factory to create git remote repo to for clone / push purposes."""
+    _skip_if_git_missing()
     if (
         empty_git_bare_repo_path.exists()
         and (empty_git_bare_repo_path / ".git").exists()
@@ -357,11 +371,11 @@ def empty_git_bare_repo(
 
 
 @pytest.fixture(scope="session")
-@skip_if_git_missing
 def empty_git_repo(
     empty_git_repo_path: pathlib.Path,
 ) -> pathlib.Path:
     """Return factory to create git remote repo to for clone / push purposes."""
+    _skip_if_git_missing()
     if empty_git_repo_path.exists() and (empty_git_repo_path / ".git").exists():
         return empty_git_repo_path
 
@@ -373,12 +387,12 @@ def empty_git_repo(
 
 
 @pytest.fixture(scope="session")
-@skip_if_git_missing
 def create_git_remote_bare_repo(
     remote_repos_path: pathlib.Path,
     empty_git_bare_repo: pathlib.Path,
 ) -> CreateRepoFn:
     """Return factory to create git remote repo to for clone / push purposes."""
+    _skip_if_git_missing()
 
     def fn(
         remote_repos_path: pathlib.Path = remote_repos_path,
@@ -402,12 +416,12 @@ def fn(
 
 
 @pytest.fixture(scope="session")
-@skip_if_git_missing
 def create_git_remote_repo(
     remote_repos_path: pathlib.Path,
     empty_git_repo: pathlib.Path,
 ) -> CreateRepoFn:
     """Return factory to create git remote repo to for clone / push purposes."""
+    _skip_if_git_missing()
 
     def fn(
         remote_repos_path: pathlib.Path = remote_repos_path,
@@ -455,13 +469,13 @@ def git_remote_repo_single_commit_post_init(
 
 
 @pytest.fixture(scope="session")
-@skip_if_git_missing
 def git_remote_repo(
     create_git_remote_repo: CreateRepoFn,
     vcs_gitconfig: pathlib.Path,
     git_commit_envvars: GitCommitEnvVars,
 ) -> pathlib.Path:
     """Copy the session-scoped Git repository to a temporary directory."""
+    _skip_if_git_missing()
     # TODO: Cache the effect of of this in a session-based repo
     repo_path = create_git_remote_repo()
     git_remote_repo_single_commit_post_init(
@@ -519,15 +533,11 @@ def empty_svn_repo_path(libvcs_test_cache_path: pathlib.Path) -> pathlib.Path:
 
 
 @pytest.fixture(scope="session")
-@skip_if_svn_missing
 def empty_svn_repo(
     empty_svn_repo_path: pathlib.Path,
 ) -> pathlib.Path:
     """Return factory to create svn remote repo to for clone / push purposes."""
-    if not shutil.which("svn") or not shutil.which("svnadmin"):
-        pytest.skip(
-            reason="svn is not available",
-        )
+    _skip_if_svn_missing()
 
     if empty_svn_repo_path.exists() and (empty_svn_repo_path / "conf").exists():
         return empty_svn_repo_path
@@ -540,12 +550,12 @@ def empty_svn_repo(
 
 
 @pytest.fixture(scope="session")
-@skip_if_svn_missing
 def create_svn_remote_repo(
     remote_repos_path: pathlib.Path,
     empty_svn_repo: pathlib.Path,
 ) -> CreateRepoFn:
     """Pre-made svn repo, bare, used as a file:// remote to checkout and commit to."""
+    _skip_if_svn_missing()
 
     def fn(
         remote_repos_path: pathlib.Path = remote_repos_path,
@@ -572,20 +582,20 @@ def fn(
 
 
 @pytest.fixture(scope="session")
-@skip_if_svn_missing
 def svn_remote_repo(
     create_svn_remote_repo: CreateRepoFn,
 ) -> pathlib.Path:
     """Pre-made. Local file:// based SVN server."""
+    _skip_if_svn_missing()
     return create_svn_remote_repo()
 
 
 @pytest.fixture(scope="session")
-@skip_if_svn_missing
 def svn_remote_repo_with_files(
     create_svn_remote_repo: CreateRepoFn,
 ) -> pathlib.Path:
     """Pre-made. Local file:// based SVN server."""
+    _skip_if_svn_missing()
     repo_path = create_svn_remote_repo()
     svn_remote_repo_single_commit_post_init(remote_repo_path=repo_path)
     return repo_path
@@ -629,11 +639,11 @@ def empty_hg_repo_path(libvcs_test_cache_path: pathlib.Path) -> pathlib.Path:
 
 
 @pytest.fixture(scope="session")
-@skip_if_hg_missing
 def empty_hg_repo(
     empty_hg_repo_path: pathlib.Path,
 ) -> pathlib.Path:
     """Return factory to create hg remote repo to for clone / push purposes."""
+    _skip_if_hg_missing()
     if empty_hg_repo_path.exists() and (empty_hg_repo_path / ".hg").exists():
         return empty_hg_repo_path
 
@@ -645,13 +655,13 @@ def empty_hg_repo(
 
 
 @pytest.fixture(scope="session")
-@skip_if_hg_missing
 def create_hg_remote_repo(
     remote_repos_path: pathlib.Path,
     empty_hg_repo: pathlib.Path,
     vcs_hgconfig: pathlib.Path,
 ) -> CreateRepoFn:
     """Pre-made hg repo, bare, used as a file:// remote to checkout and commit to."""
+    _skip_if_hg_missing()
 
     def fn(
         remote_repos_path: pathlib.Path = remote_repos_path,
@@ -681,13 +691,13 @@ def fn(
 
 
 @pytest.fixture(scope="session")
-@skip_if_hg_missing
 def hg_remote_repo(
     remote_repos_path: pathlib.Path,
     create_hg_remote_repo: CreateRepoFn,
     vcs_hgconfig: pathlib.Path,
 ) -> pathlib.Path:
     """Pre-made, file-based repo for push and pull."""
+    _skip_if_hg_missing()
     repo_path = create_hg_remote_repo()
     hg_remote_repo_single_commit_post_init(
         remote_repo_path=repo_path,
@@ -790,20 +800,18 @@ def add_doctest_fixtures(
     doctest_namespace: dict[str, t.Any],
     tmp_path: pathlib.Path,
     set_home: pathlib.Path,
-    git_commit_envvars: GitCommitEnvVars,
-    vcs_hgconfig: pathlib.Path,
-    create_git_remote_repo: CreateRepoFn,
-    create_svn_remote_repo: CreateRepoFn,
-    create_hg_remote_repo: CreateRepoFn,
-    git_repo: pathlib.Path,
 ) -> None:
     """Harness pytest fixtures to pytest's doctest namespace."""
     from _pytest.doctest import DoctestItem
 
     if not isinstance(request._pyfuncitem, DoctestItem):  # Only run on doctest items
         return
     doctest_namespace["tmp_path"] = tmp_path
+    # Request the per-VCS fixtures lazily so a missing binary only drops that
+    # VCS's doctest helpers -- it does not skip doctests for the others.
     if shutil.which("git"):
+        git_commit_envvars = request.getfixturevalue("git_commit_envvars")
+        create_git_remote_repo = request.getfixturevalue("create_git_remote_repo")
         doctest_namespace["create_git_remote_repo"] = functools.partial(
             create_git_remote_repo,
             remote_repo_post_init=functools.partial(
@@ -813,14 +821,17 @@ def add_doctest_fixtures(
             init_cmd_args=None,
         )
         doctest_namespace["create_git_remote_repo_bare"] = create_git_remote_repo
-        doctest_namespace["example_git_repo"] = git_repo
-    if shutil.which("svn"):
+        doctest_namespace["example_git_repo"] = request.getfixturevalue("git_repo")
+    if shutil.which("svn") and shutil.which("svnadmin"):
+        create_svn_remote_repo = request.getfixturevalue("create_svn_remote_repo")
         doctest_namespace["create_svn_remote_repo_bare"] = create_svn_remote_repo
         doctest_namespace["create_svn_remote_repo"] = functools.partial(
             create_svn_remote_repo,
             remote_repo_post_init=svn_remote_repo_single_commit_post_init,
         )
     if shutil.which("hg"):
+        vcs_hgconfig = request.getfixturevalue("vcs_hgconfig")
+        create_hg_remote_repo = request.getfixturevalue("create_hg_remote_repo")
         doctest_namespace["create_hg_remote_repo_bare"] = create_hg_remote_repo
         doctest_namespace["create_hg_remote_repo"] = functools.partial(
             create_hg_remote_repo,