Fixed git worktree issue

- uses the correct git command depending on the parameters passed.

cookie_composer/git_commands.py

@@ -7,7 +7,7 @@
 from pathlib import Path
 from typing import Iterator, Optional, Union
 
-from git import InvalidGitRepositoryError, NoSuchPathError, Repo
+from git import GitCommandError, InvalidGitRepositoryError, NoSuchPathError, Repo
 
 from cookie_composer.exceptions import GitError
 from cookie_composer.utils import echo
@@ -194,14 +194,22 @@ def apply_patch(repo: Repo, diff: str) -> None:
 
 @contextmanager
 def temp_git_worktree_dir(
-    repo_path: Path, worktree_path: Optional[Path] = None, branch: str = "master", commit: Optional[str] = None
+    repo_path: Path, worktree_path: Optional[Path] = None, branch: Optional[str] = None, commit: Optional[str] = None
 ) -> Iterator[Path]:
     """
     Context Manager for a temporary working directory of a branch in a git repo.
 
     Inspired by https://github.com/thomasjahoda/cookiecutter_project_upgrader/blob/master/
     cookiecutter_project_upgrader/logic.py
 
+    Logic for checking out a branch or commit:
+
+    - If a commit is provided, use that
+    - If a branch is provided, and it is not the current branch, use that
+    - If a branch is provided, and it is the current branch, use the current commit
+    - If neither a branch nor a commit is provided, use the current branch and commit
+
+
     Args:
         repo_path: The path to the template git repo
         worktree_path: The path put the worktree in. Defaults to a temporary directory.
@@ -210,19 +218,27 @@ def temp_git_worktree_dir(
 
     Yields:
         The worktree_path
+
+    Raises:
+        GitError: If the worktree could not be created
     """
     # Create a temporary working directory of a branch in a git repo.
     repo = get_repo(repo_path)
+
     tmp_dir = Path(tempfile.mkdtemp(prefix=repo_path.name))
     worktree_path = worktree_path or tmp_dir
     worktree_path.mkdir(parents=True, exist_ok=True)
-    repo.git.worktree(
-        "add",
-        str(worktree_path),
-        commit or branch,
-    )
+
+    branch_is_active_branch = branch is None or branch == repo.active_branch.name
+    git_cmd = ["add", str(worktree_path), commit or branch]
+    if branch_is_active_branch and commit is None:
+        git_cmd = ["add", "-d", str(worktree_path)]
+
     try:
+        repo.git.worktree(*git_cmd)
         yield Path(worktree_path)
+    except GitCommandError as e:
+        raise GitError(f"Could not create a worktree for {repo_path}") from e
     finally:
         # Clean up the temporary working directory.
         shutil.rmtree(worktree_path)

pyproject.toml

@@ -265,4 +265,5 @@ exclude = '\.git|tests'
 require-return-section-when-returning-nothing = false
 arg-type-hints-in-docstring = false
 check-return-types = false
+check-yield-types = false
 quiet = true

tests/test_layers.py

@@ -237,6 +237,58 @@ def test_render_layer_git_template(fixtures_path: Path, tmp_path: Path):
     }
 
 
+def test_render_layer_git_template_branch(fixtures_path: Path, tmp_path: Path):
+    """Render a layer of a git-based template specifying a branch."""
+    from git import Actor, Repo
+
+    template_path = fixtures_path / "template1"
+    git_tmpl_path = copytree(template_path, tmp_path / "template1")
+    repo = Repo.init(str(git_tmpl_path))
+    repo.git.add(".")
+    repo.index.commit(
+        message="Another commit", committer=Actor("Bob", "bob@example.com"), commit_date="2022-01-02 10:00:00"
+    )
+    repo.create_head("my-branch")
+    repo.heads["my-branch"].checkout()
+    git_tmpl_path.joinpath("newfile.md").write_text("Hello World!\n\nThis is a test.\n\nThis is a new line.")
+    repo.index.add(["newfile.md"])
+    repo.index.commit(
+        message="first commit on a branch",
+        committer=Actor("Bob", "bob@example.com"),
+        commit_date="2022-01-01 12:00:00",
+    )
+    latest_sha = repo.head.commit.hexsha
+
+    assert latest_sha is not None
+
+    template = Template(
+        repo=get_template_repo(str(git_tmpl_path), tmp_path, checkout="my-branch"),
+    )
+    assert template.repo.format == "git"
+    assert template.repo.latest_sha == latest_sha
+
+    layer_conf = LayerConfig(template=template, no_input=True)
+    render_dir = tmp_path / "render"
+    rendered_layer = layers.render_layer(layer_conf, render_dir)
+    expected_context = template.context
+    expected_context["repo_name"] = "fake-project-template"
+    expected_context["repo_slug"] = "fake-project-template"
+    expected = RenderedLayer(
+        layer=layer_conf,
+        location=render_dir,
+        rendered_context=expected_context,
+        rendered_commit=latest_sha,
+    )
+    assert rendered_layer == expected
+    assert rendered_layer.latest_commit == latest_sha
+    assert rendered_layer.layer.template.repo.latest_sha == latest_sha
+    assert {x.name for x in Path(render_dir / "fake-project-template").iterdir()} == {
+        "README.md",
+        "requirements.txt",
+        "demo.jinja",
+    }
+
+
 @pytest.mark.parametrize(
     ("default_context", "initial_context", "full_context", "expected"),
     [