feat: add --range flag for checking multiple commits in CI

README.md

@@ -146,16 +146,18 @@ provided.
 
 ### Checking a range of commits
 
+Use `--range` to check all commits in a revision range. All commits are
+checked and a single non-zero exit code is returned if any fail:
+
 ```bash
-# all non-merge commits between tags
-git rev-list --no-merges v1.0..v2.0 | while read -r rev; do
-    commit-guard "$rev" || git log -1 --oneline "$rev"
-done
-
-# only subject checks on a PR range
-git rev-list --no-merges origin/main..HEAD | while read -r rev; do
-    commit-guard "$rev" --enable subject,imperative
-done
+# check all commits in a PR
+commit-guard --range origin/main..HEAD
+
+# check between two tags
+commit-guard --range v1.0..v2.0
+
+# only subject checks on a range
+commit-guard --range origin/main..HEAD --enable subject,imperative
 ```
 
 ### pre-commit

src/git_commit_guard/__init__.py

@@ -224,6 +224,19 @@ def _get_message(rev):
         sys.exit(f"git error: {stderr}")
 
 
+def _get_range_revs(rev_range):
+    try:
+        output = subprocess.check_output(  # noqa: S603
+            ["git", "log", "--format=%H", rev_range],  # noqa: S607
+            text=True,
+            stderr=subprocess.PIPE,
+            timeout=GIT_TIMEOUT,
+        ).strip()
+    except subprocess.CalledProcessError as e:
+        sys.exit(f"git error: {e.stderr.strip()}")
+    return output.split("\n") if output else []
+
+
 @dataclass
 class Args:
     rev: str | None
@@ -233,6 +246,7 @@ class Args:
     require_scope: bool
     allowed_types: frozenset
     max_subject_length: int
+    rev_range: str | None
 
 
 def _resolve_enabled(args, config, parser):
@@ -330,14 +344,25 @@ def _parse_args():
         metavar="N",
         help=f"maximum subject line length (default: {MAX_SUBJECT_LEN})",
     )
+    parser.add_argument(
+        "--range",
+        dest="rev_range",
+        metavar="REF..REF",
+        help="check all commits in the given revision range",
+    )
     args = parser.parse_args()
     config = _load_config()
     enabled = _resolve_enabled(args, config, parser)
     allowed_scopes, require_scope = _resolve_scopes(args, config)
     allowed_types = _resolve_types(args, config)
     max_subject_length = _resolve_max_subject_length(args, config)
 
-    if args.message_file:
+    if args.rev_range:
+        if args.rev is not None or args.message_file:
+            parser.error("--range cannot be combined with rev or --message-file")
+        rev = None
+        message = ""
+    elif args.message_file:
         rev = None
         message = _strip_comments(args.message_file.read_text().strip())
     elif args.rev:
@@ -358,6 +383,7 @@ def _parse_args():
         require_scope=require_scope,
         allowed_types=allowed_types,
         max_subject_length=max_subject_length,
+        rev_range=args.rev_range,
     )
 
 
@@ -371,15 +397,8 @@ def _report(result):
     return 0 if result.ok else 1
 
 
-def main():
-    args = _parse_args()
-    lines = args.message.split("\n")
-
-    if Check.IMPERATIVE in args.enabled:
-        _ensure_nltk_data()
-
-    result = Result()
-
+def _run_checks(args, rev, message, result):
+    lines = message.split("\n")
     desc = None
     if Check.SUBJECT in args.enabled:
         desc = check_subject(
@@ -399,8 +418,32 @@ def main():
     if Check.BODY in args.enabled:
         check_body(lines, result)
     if Check.SIGNED_OFF in args.enabled:
-        check_signed_off(args.message, result)
-    if Check.SIGNATURE in args.enabled and args.rev:
-        check_signature(args.rev, result)
+        check_signed_off(message, result)
+    if Check.SIGNATURE in args.enabled and rev:
+        check_signature(rev, result)
+
+
+def main():
+    args = _parse_args()
 
+    if Check.IMPERATIVE in args.enabled:
+        _ensure_nltk_data()
+
+    if args.rev_range:
+        revs = _get_range_revs(args.rev_range)
+        if not revs:
+            sys.stderr.write("no commits in range\n")
+            return 0
+        failed = False
+        for rev in revs:
+            message = _strip_comments(_get_message(rev))
+            sys.stderr.write(f"{rev[:7]} {message.split('\n')[0]}\n")
+            result = Result()
+            _run_checks(args, rev, message, result)
+            if _report(result) != 0:
+                failed = True
+        return 1 if failed else 0
+
+    result = Result()
+    _run_checks(args, args.rev, args.message, result)
     return _report(result)

tests/test_git_commit_guard.py

@@ -11,6 +11,7 @@
     _download_if_missing,
     _ensure_nltk_data,
     _get_message,
+    _get_range_revs,
     _load_config,
     _parse_checks,
     _parse_config_checks,
@@ -831,3 +832,113 @@ def test_types_cli_overrides_config(self, tmp_path):
             ),
         ):
             assert main() == 0
+
+    def test_range_all_pass(self):
+        with (
+            patch(
+                "sys.argv",
+                ["cg", "--range", "origin/main..HEAD", "--disable", "signature"],
+            ),
+            patch(
+                "git_commit_guard._get_range_revs",
+                return_value=["abc1234", "def5678"],
+            ),
+            patch("git_commit_guard._get_message", return_value=_VALID_MSG),
+        ):
+            assert main() == 0
+
+    def test_range_one_fails(self):
+        messages = {"abc1234": _VALID_MSG, "def5678": "not a valid commit message"}
+        with (
+            patch(
+                "sys.argv",
+                [
+                    "cg",
+                    "--range",
+                    "origin/main..HEAD",
+                    "--disable",
+                    "signature,body,signed-off,imperative",
+                ],
+            ),
+            patch(
+                "git_commit_guard._get_range_revs",
+                return_value=["abc1234", "def5678"],
+            ),
+            patch(
+                "git_commit_guard._get_message",
+                side_effect=lambda rev: messages[rev],
+            ),
+        ):
+            assert main() == 1
+
+    def test_range_all_fail_returns_one(self):
+        with (
+            patch(
+                "sys.argv",
+                [
+                    "cg",
+                    "--range",
+                    "origin/main..HEAD",
+                    "--disable",
+                    "signature,body,signed-off,imperative",
+                ],
+            ),
+            patch(
+                "git_commit_guard._get_range_revs",
+                return_value=["abc1234"],
+            ),
+            patch(
+                "git_commit_guard._get_message",
+                return_value="not a valid commit message",
+            ),
+        ):
+            assert main() == 1
+
+    def test_range_empty_returns_zero(self, capsys):
+        with (
+            patch("sys.argv", ["cg", "--range", "origin/main..HEAD"]),
+            patch("git_commit_guard._get_range_revs", return_value=[]),
+        ):
+            assert main() == 0
+        assert "no commits in range" in capsys.readouterr().err
+
+    def test_range_conflicts_with_rev(self):
+        with (
+            patch("sys.argv", ["cg", "abc123", "--range", "origin/main..HEAD"]),
+            pytest.raises(SystemExit),
+        ):
+            main()
+
+    def test_range_conflicts_with_message_file(self, tmp_path):
+        f = tmp_path / "msg"
+        f.write_text(_VALID_MSG)
+        with (
+            patch(
+                "sys.argv",
+                ["cg", "--message-file", str(f), "--range", "origin/main..HEAD"],
+            ),
+            pytest.raises(SystemExit),
+        ):
+            main()
+
+
+class TestGetRangeRevs:
+    def test_returns_shas(self):
+        with patch(
+            "git_commit_guard.subprocess.check_output",
+            return_value="abc1234\ndef5678",
+        ):
+            assert _get_range_revs("origin/main..HEAD") == ["abc1234", "def5678"]
+
+    def test_empty_range_returns_empty_list(self):
+        with patch("git_commit_guard.subprocess.check_output", return_value=""):
+            assert _get_range_revs("origin/main..HEAD") == []
+
+    def test_invalid_range_exits(self):
+        err = subprocess.CalledProcessError(128, "git")
+        err.stderr = "fatal: bad revision 'bogus'"
+        with (
+            patch("git_commit_guard.subprocess.check_output", side_effect=err),
+            pytest.raises(SystemExit, match="git error"),
+        ):
+            _get_range_revs("bogus")