feat: add an argument to limit the length of commit message

commitizen/cli.py

@@ -154,6 +154,12 @@ def __call__(
                         "action": "store_true",
                         "help": "Tell the command to automatically stage files that have been modified and deleted, but new files you have not told Git about are not affected.",
                     },
+                    {
+                        "name": ["-l", "--message-length-limit"],
+                        "type": int,
+                        "default": 0,
+                        "help": "length limit of the commit message; 0 for no limit",
+                    },
                 ],
             },
             {

commitizen/commands/commit.py

@@ -61,7 +61,9 @@ def prompt_commit_questions(self) -> str:
 
         if not answers:
             raise NoAnswersError()
-        return cz.message(answers)
+
+        message_length_limit: int = self.arguments.get("message_length_limit", 0)
+        return cz.message(answers, message_length_limit=message_length_limit)
 
     def __call__(self):
         dry_run: bool = self.arguments.get("dry_run")

commitizen/cz/base.py

@@ -9,6 +9,7 @@
 from commitizen import git
 from commitizen.config.base_config import BaseConfig
 from commitizen.defaults import Questions
+from commitizen.exceptions import CommitMessageLengthExceededError
 
 
 class MessageBuilderHook(Protocol):
@@ -71,7 +72,7 @@ def questions(self) -> Questions:
         """Questions regarding the commit message."""
 
     @abstractmethod
-    def message(self, answers: dict) -> str:
+    def message(self, answers: dict, message_length_limit: int) -> str:
         """Format your git message."""
 
     @property
@@ -105,3 +106,12 @@ def process_commit(self, commit: str) -> str:
         If not overwritten, it returns the first line of commit.
         """
         return commit.split("\n")[0]
+
+    def _check_message_length_limit(
+        self, message: str, message_length_limit: int
+    ) -> None:
+        message_len = len(message)
+        if message_length_limit > 0 and message_len > message_length_limit:
+            raise CommitMessageLengthExceededError(
+                f"Length of commit message exceeds limit ({message_len}/{message_length_limit})"
+            )

commitizen/cz/conventional_commits/conventional_commits.py

@@ -150,7 +150,7 @@ def questions(self) -> Questions:
         ]
         return questions
 
-    def message(self, answers: dict) -> str:
+    def message(self, answers: dict, message_length_limit: int = 0) -> str:
         prefix = answers["prefix"]
         scope = answers["scope"]
         subject = answers["subject"]
@@ -167,9 +167,9 @@ def message(self, answers: dict) -> str:
         if footer:
             footer = f"\n\n{footer}"
 
-        message = f"{prefix}{scope}: {subject}{body}{footer}"
-
-        return message
+        message = f"{prefix}{scope}: {subject}"
+        self._check_message_length_limit(message, message_length_limit)
+        return f"{message}{body}{footer}"
 
     def example(self) -> str:
         return (

commitizen/cz/customize/customize.py

@@ -61,12 +61,15 @@ def __init__(self, config: BaseConfig):
     def questions(self) -> Questions:
         return self.custom_settings.get("questions", [{}])
 
-    def message(self, answers: dict) -> str:
+    def message(self, answers: dict, message_length_limit: int = 0) -> str:
         message_template = Template(self.custom_settings.get("message_template", ""))
-        if getattr(Template, "substitute", None):
-            return message_template.substitute(**answers)  # type: ignore
-        else:
-            return message_template.render(**answers)
+        message: str = (
+            message_template.substitute(**answers)  # type: ignore
+            if getattr(Template, "substitute", None)
+            else message_template.render(**answers)
+        )
+        self._check_message_length_limit(message, message_length_limit)
+        return message
 
     def example(self) -> str | None:
         return self.custom_settings.get("example")

commitizen/cz/jira/jira.py

@@ -44,8 +44,8 @@ def questions(self) -> Questions:
         ]
         return questions
 
-    def message(self, answers) -> str:
-        return " ".join(
+    def message(self, answers: dict, message_length_limit: int = 0) -> str:
+        message = " ".join(
             filter(
                 bool,
                 [
@@ -57,6 +57,8 @@ def message(self, answers) -> str:
                 ],
             )
         )
+        self._check_message_length_limit(message, message_length_limit)
+        return message
 
     def example(self) -> str:
         return (

commitizen/exceptions.py

@@ -36,6 +36,7 @@ class ExitCode(enum.IntEnum):
     CHANGELOG_FORMAT_UNKNOWN = 29
     CONFIG_FILE_NOT_FOUND = 30
     CONFIG_FILE_IS_EMPTY = 31
+    COMMIT_MESSAGE_LENGTH_LIMIT_EXCEEDED = 32
 
 
 class CommitizenException(Exception):
@@ -201,3 +202,7 @@ class ConfigFileNotFound(CommitizenException):
 class ConfigFileIsEmpty(CommitizenException):
     exit_code = ExitCode.CONFIG_FILE_IS_EMPTY
     message = "Config file is empty, please check your file path again."
+
+
+class CommitMessageLengthExceededError(CommitizenException):
+    exit_code = ExitCode.COMMIT_MESSAGE_LENGTH_LIMIT_EXCEEDED

docs/commit.md

@@ -36,3 +36,13 @@ You can use `cz commit --retry` to reuse the last commit message when the previo
 To automatically retry when running `cz commit`, you can set the `retry_after_failure`
 configuration option to `true`. Running `cz commit --no-retry` makes commitizen ignore `retry_after_failure`, forcing
 a new commit message to be prompted.
+
+### Commit message length limit
+
+The argument `-l` (or `--message-length-limit`) followed by a positive number can limit the length of commit messages.
+An exception would be raised when the message length exceeds the limit.
+For example, `cz commit -l 72` will limit the length of commit messages to 72 characters.
+By default the limit is set to 0, which means no limit on the length.
+
+Note that for `ConventionalCommitsCz`, the limit applies only from the prefix to the subject.
+In other words, everything after the first line (the body and the footer) are not counted in the length.

docs/customization.md

@@ -227,9 +227,11 @@ class JiraCz(BaseCommitizen):
         ]
         return questions
 
-    def message(self, answers: dict) -> str:
+    def message(self, answers: dict, message_length_limit: int = 0) -> str:
         """Generate the message with the given answers."""
-        return "{0} (#{1})".format(answers["title"], answers["issue"])
+        message = "{0} (#{1})".format(answers["title"], answers["issue"])
+        self._check_message_length_limit(message, message_length_limit)
+        return message
 
     def example(self) -> str:
         """Provide an example to help understand the style (OPTIONAL)

tests/conftest.py

@@ -204,10 +204,12 @@ def questions(self) -> list:
             },
         ]
 
-    def message(self, answers: dict) -> str:
+    def message(self, answers: dict, message_length_limit: int = 0) -> str:
         prefix = answers["prefix"]
         subject = answers.get("subject", "default message").trim()
-        return f"{prefix}: {subject}"
+        message = f"{prefix}: {subject}"
+        self._check_message_length_limit(message, message_length_limit)
+        return message
 
 
 @pytest.fixture()
@@ -220,7 +222,7 @@ class MockPlugin(BaseCommitizen):
     def questions(self) -> defaults.Questions:
         return []
 
-    def message(self, answers: dict) -> str:
+    def message(self, answers: dict, message_length_limit: int = 0) -> str:
         return ""
 
 

tests/test_cz_base.py

@@ -1,14 +1,17 @@
 import pytest
 
 from commitizen.cz.base import BaseCommitizen
+from commitizen.exceptions import CommitMessageLengthExceededError
 
 
 class DummyCz(BaseCommitizen):
     def questions(self):
         return [{"type": "input", "name": "commit", "message": "Initial commit:\n"}]
 
-    def message(self, answers):
-        return answers["commit"]
+    def message(self, answers: dict, message_length_limit: int = 0):
+        message = answers["commit"]
+        self._check_message_length_limit(message, message_length_limit)
+        return message
 
 
 def test_base_raises_error(config):
@@ -48,3 +51,16 @@ def test_process_commit(config):
     cz = DummyCz(config)
     message = cz.process_commit("test(test_scope): this is test msg")
     assert message == "test(test_scope): this is test msg"
+
+
+def test_message_length_limit(config):
+    cz = DummyCz(config)
+    commit_message = "123456789"
+    message_length = len(commit_message)
+    assert cz.message({"commit": commit_message}) == commit_message
+    assert (
+        cz.message({"commit": commit_message}, message_length_limit=message_length)
+        == commit_message
+    )
+    with pytest.raises(CommitMessageLengthExceededError):
+        cz.message({"commit": commit_message}, message_length_limit=message_length - 1)