refactor: add get_last_commit_on_branch_or_tag alongisde tests

Signed-off-by: Dariusz Duda <[email protected]>

craft_application/git/_git_repo.py

@@ -248,6 +248,52 @@ def get_last_commit(self) -> Commit:
                 message=commit_message,
             )
 
+    def get_last_commit_on_branch_or_tag(
+        self,
+        branch_or_tag: str,
+        *,
+        remote: str | None = None,
+        fetch: bool = False,
+    ) -> Commit:
+        """Find last commit corresponding to given branch or tag."""
+        if fetch and remote is not None:
+            self.fetch(remote=remote, tags=True)
+        rev_list_output = [
+            self.git_binary(),
+            "rev-list",
+            "-n",
+            "1",
+            branch_or_tag,
+        ]
+        try:
+            rev_parse_output = subprocess.check_output(
+                rev_list_output,
+                text=True,
+                stderr=subprocess.STDOUT,
+            )
+        except subprocess.CalledProcessError as error:
+            error_details = (
+                f"cannot find ref: {branch_or_tag!r}.\nCommand output:\n{error.stdout}"
+            )
+            raise GitError(error_details) from error
+
+        commit_sha = rev_parse_output.strip()
+        try:
+            commit_obj = self._repo.get(commit_sha)
+        except (pygit2.GitError, ValueError) as error:
+            raise GitError(
+                f"cannot find commit: {short_commit_sha(commit_sha)!r}"
+            ) from error
+        else:
+            commit_message = cast(
+                str,
+                commit_obj.message,  # pyright: ignore[reportOptionalMemberAccess,reportAttributeAccessIssue,reportUnknownMemberType]
+            )
+            return Commit(
+                sha=commit_sha,
+                message=commit_message,
+            )
+
     def is_clean(self) -> bool:
         """Check if the repo is clean.
 
@@ -575,48 +621,6 @@ def remote_contains(
                     return True
         return False
 
-    def last_commit_on_branch_or_tag(
-        self,
-        *,
-        remote: str,
-        branch_or_tag: str,
-        fetch: bool = False,
-    ) -> Commit:
-        """Find last commit corresponding to given branch or tag."""
-        if fetch:
-            self.fetch(remote=remote, tags=True)
-        rev_list_output = [
-            self.git_binary(),
-            "rev-list",
-            "-n",
-            "1",
-            branch_or_tag,
-        ]
-        try:
-            rev_parse_output = subprocess.check_output(
-                rev_list_output,
-                text=True,
-                stderr=subprocess.STDOUT,
-            )
-        except subprocess.CalledProcessError as error:
-            error_details = (
-                f"Cannot find ref {branch_or_tag!r}.\nCommand output:\n{error.stdout}"
-            )
-            raise GitError(error_details) from error
-
-        commit_sha = rev_parse_output.strip()
-        commit_obj = self._repo.get(commit_sha)
-        if commit_obj is None:
-            raise GitError(f"Cannot find commit: {short_commit_sha(commit_sha)!r}")
-        commit_message = cast(
-            str,
-            commit_obj.message,  # pyright: ignore[reportAttributeAccessIssue,reportUnknownMemberType]
-        )
-        return Commit(
-            sha=commit_sha,
-            message=commit_message,
-        )
-
     def describe(
         self,
         *,

tests/integration/git/test_git.py

@@ -31,7 +31,7 @@ def test_fetching_hello_repository(
     ref = "ubuntu/noble"
     git_repo.add_remote(test_remote, hello_repository_lp_url)
     git_repo.fetch(remote=test_remote, ref=ref, depth=1)
-    last_commit_on_fetched_ref = git_repo.last_commit_on_branch_or_tag(
+    last_commit_on_fetched_ref = git_repo.get_last_commit_on_branch_or_tag(
         remote=test_remote, branch_or_tag=f"{test_remote}/{ref}"
     )
     assert isinstance(

tests/unit/git/test_git.py

@@ -1289,3 +1289,57 @@ def test_craftgit_is_used_for_git_operations(
     assert git_repo.git_binary() == expected_binary
 
     which_mock.assert_called_once_with(CRAFTGIT_BINARY_NAME)
+
+
+def test_last_commit_on_branch_or_tag_fails_if_commit_not_found(
+    empty_repository: Path,
+    fake_process: pytest_subprocess.FakeProcess,
+    expected_git_binary: str,
+) -> None:
+    git_repo = GitRepo(empty_repository)
+    branch_or_tag = "test"
+    commit = "non-existent-commit"
+    fake_process.register(
+        [expected_git_binary, "rev-list", "-n", "1", branch_or_tag],
+        stdout=commit,
+    )
+    with pytest.raises(GitError) as git_error:
+        git_repo.get_last_commit_on_branch_or_tag(branch_or_tag)
+    assert (
+        git_error.value.details == f"cannot find commit: {short_commit_sha(commit)!r}"
+    )
+
+
+def test_last_commit_on_branch_or_tag_fails_if_ref_not_found(
+    empty_repository: Path,
+    fake_process: pytest_subprocess.FakeProcess,
+    expected_git_binary: str,
+) -> None:
+    git_repo = GitRepo(empty_repository)
+    branch_or_tag = "test"
+    fake_process.register(
+        [expected_git_binary, "rev-list", "-n", "1", branch_or_tag],
+        returncode=1,
+        stderr=f"fatal: ambiguous argument {branch_or_tag!r}",
+    )
+    with pytest.raises(GitError) as git_error:
+        git_repo.get_last_commit_on_branch_or_tag(branch_or_tag)
+    err_details = cast(str, git_error.value.details)
+    assert err_details.startswith(f"cannot find ref: {branch_or_tag!r}")
+    assert "fatal" in err_details
+
+
+def test_get_last_commit_on_branch_or_tag(
+    repository_with_commit: RepositoryDefinition,
+    fake_process: pytest_subprocess.FakeProcess,
+    expected_git_binary: str,
+) -> None:
+    git_repo = GitRepo(repository_with_commit.repository_path)
+    branch_or_tag = "test"
+    last_commit = git_repo.get_last_commit()
+    fake_process.register(
+        [expected_git_binary, "rev-list", "-n", "1", branch_or_tag],
+        stdout=last_commit.sha,
+    )
+    last_commit_on_branch = git_repo.get_last_commit_on_branch_or_tag(branch_or_tag)
+    assert last_commit_on_branch == last_commit