fix(check): support first pushes in the 'commitizen-branch' hook

Details: When a push includes the root commit (first push to an empty
         remote, or a new unrelated history), pre-commit does not set
         'PRE_COMMIT_FROM_REF' and 'PRE_COMMIT_TO_REF'. The
         'commitizen-branch' hook then fails with:
> fatal: ambiguous argument '$PRE_COMMIT_FROM_REF..$PRE_COMMIT_TO_REF'
         In this case, check all commits of 'PRE_COMMIT_LOCAL_BRANCH',
         since they are all new to the remote.
---

Signed-off-by: Adrian DC <radian.dc@gmail.com>

Author: AdrianDC

commitizen/commands/check.py

@@ -42,6 +42,13 @@ def __init__(self, config: BaseConfig, arguments: CheckArgs, *args: object) -> N
         self.commit_msg_file = arguments.get("commit_msg_file")
         self.commit_msg = arguments.get("message")
         rev_range = arguments.get("rev_range")
+        if (
+            rev_range == "$PRE_COMMIT_FROM_REF..$PRE_COMMIT_TO_REF"
+            and "PRE_COMMIT_FROM_REF" not in os.environ
+            and "PRE_COMMIT_LOCAL_BRANCH" in os.environ
+        ):
+            # pre-commit omits the refs when the push includes the root commit
+            rev_range = "$PRE_COMMIT_LOCAL_BRANCH"
         # Expand env vars so the packaged ``commitizen-branch`` pre-push hook
         # (which passes the literal ``$PRE_COMMIT_FROM_REF..$PRE_COMMIT_TO_REF``)
         # keeps working after the ``shell=False`` switch in #1941. See #2003.

tests/commands/test_check_command.py

@@ -204,6 +204,7 @@ def test_check_rev_range_leaves_unset_env_vars_literal(
     rewritten to an empty range."""
     monkeypatch.delenv("PRE_COMMIT_FROM_REF", raising=False)
     monkeypatch.delenv("PRE_COMMIT_TO_REF", raising=False)
+    monkeypatch.delenv("PRE_COMMIT_LOCAL_BRANCH", raising=False)
     get_commits = mocker.patch(
         "commitizen.git.get_commits",
         return_value=_build_fake_git_commits(COMMIT_LOG),
@@ -219,6 +220,26 @@ def test_check_rev_range_leaves_unset_env_vars_literal(
     )
 
 
+def test_check_rev_range_falls_back_to_pushed_branch_on_root_push(
+    config, mocker: MockFixture, monkeypatch: pytest.MonkeyPatch
+):
+    """pre-commit omits the from/to refs when a push includes the root commit."""
+    monkeypatch.delenv("PRE_COMMIT_FROM_REF", raising=False)
+    monkeypatch.delenv("PRE_COMMIT_TO_REF", raising=False)
+    monkeypatch.setenv("PRE_COMMIT_LOCAL_BRANCH", "refs/heads/main")
+    get_commits = mocker.patch(
+        "commitizen.git.get_commits",
+        return_value=_build_fake_git_commits(COMMIT_LOG),
+    )
+
+    commands.Check(
+        config=config,
+        arguments={"rev_range": "$PRE_COMMIT_FROM_REF..$PRE_COMMIT_TO_REF"},
+    )()
+
+    get_commits.assert_called_once_with(None, "refs/heads/main")
+
+
 def test_check_command_with_invalid_argument(config):
     with pytest.raises(
         InvalidCommandArgumentError,