feat: Support Git trailers, render them in Keep A Changelog template

cdf17c03 · Timothée Mazzucotelli · f7517368 · cdf17c03 · cdf17c03 · cdf17c03
--- a/src/git_changelog/build.py
+++ b/src/git_changelog/build.py
@@ -159,6 +159,7 @@ class Changelog:
        provider: ProviderRefParser | None = None,
        style: StyleType | None = None,
        parse_provider_refs: bool = True,
+        parse_trailers: bool = False,
    ):
        """
        Initialization method.
@@ -168,9 +169,11 @@ class Changelog:
            provider: The provider to use (github.com, gitlab.com, etc.).
            style: The commit style to use (angular, atom, etc.).
            parse_provider_refs: Whether to parse provider-specific references in the commit messages.
+            parse_trailers: Whether to parse Git trailers in the commit messages.
        """
        self.repository: str = repository
        self.parse_provider_refs: bool = parse_provider_refs
+        self.parse_trailers: bool = parse_trailers

        # set provider
        if not provider:
@@ -297,6 +300,7 @@ class Changelog:
                refs=lines[pos + 7],
                subject=lines[pos + 8],
                body=body,
+                parse_trailers=self.parse_trailers,
            )

            # expand commit object with provider parsing

--- a/src/git_changelog/cli.py
+++ b/src/git_changelog/cli.py
@@ -100,6 +100,14 @@ def get_parser() -> argparse.ArgumentParser:
        help='The Jinja2 template to use. Prefix with "path:" to specify the path '
        'to a directory containing a file named "changelog.md".',
    )
+    parser.add_argument(
+        "-T",
+        "--trailers",
+        action="store_true",
+        default=False,
+        dest="parse_trailers",
+        help="Parse Git trailers in the commit message. See https://git-scm.com/docs/git-interpret-trailers.",
+    )
    parser.add_argument(
        "-v",
        "--version",
@@ -141,6 +149,7 @@ def main(args: list[str] | None = None) -> int:
        opts.repository,
        style=opts.style,
        parse_provider_refs=opts.parse_refs,
+        parse_trailers=opts.parse_trailers,
    )

    # get rendered contents

--- a/src/git_changelog/commit.py
+++ b/src/git_changelog/commit.py
@@ -4,6 +4,7 @@ from __future__ import annotations

 import re
 from abc import ABC, abstractmethod
+from contextlib import suppress
 from datetime import datetime
 from typing import Any, Pattern

@@ -13,7 +14,7 @@ from git_changelog.providers import ProviderRefParser, Ref
 class Commit:
    """A class to represent a commit."""

-    def __init__(
+    def __init__(  # noqa: WPS231
        self,
        commit_hash: str,
        author_name: str = "",
@@ -26,6 +27,7 @@ class Commit:
        subject: str = "",
        body: list[str] | None = None,
        url: str = "",
+        parse_trailers: bool = False,
    ):
        """
        Initialization method.
@@ -42,6 +44,7 @@ class Commit:
            subject: The commit message subject.
            body: The commit message body.
            url: The commit URL.
+            parse_trailers: Whether to parse Git trailers.
        """
        if not author_date:
            author_date = datetime.now()
@@ -75,6 +78,12 @@ class Commit:
        self.text_refs: dict[str, list[Ref]] = {}
        self.style: dict[str, Any] = {}

+        self.trailers: dict[str, str] = {}
+        self.body_without_trailers = self.body
+
+        if parse_trailers:
+            self._parse_trailers()
+
    def update_with_style(self, style: "CommitStyle") -> None:
        """
        Apply the style-parsed data to this commit.
@@ -111,6 +120,24 @@ class Commit:
                    if issue.ref not in self.subject:
                        self.text_refs["issues_not_in_subject"].append(issue)

+    def _parse_trailers(self) -> None:
+        last_blank_line = -1
+        for index, line in enumerate(self.body):
+            if not line:
+                last_blank_line = index
+        with suppress(ValueError):
+            trailers = self._parse_trailers_block(self.body[last_blank_line + 1 :])
+            if trailers:
+                self.trailers.update(trailers)
+                self.body_without_trailers = self.body[:last_blank_line]
+
+    def _parse_trailers_block(self, lines: list[str]) -> dict[str, str]:
+        trailers = {}
+        for line in lines:
+            title, value = line.split(": ", 1)
+            trailers[title] = value.strip()
+        return trailers  # or raise ValueError due to split unpacking
+

 class CommitStyle(ABC):
    """A base class for a style of commit messages."""

--- a/src/git_changelog/templates/__init__.py
+++ b/src/git_changelog/templates/__init__.py
@@ -3,10 +3,15 @@
 from __future__ import annotations

 import os
+from urllib.parse import urlparse

 from jinja2 import Environment, FileSystemLoader, Template


+def _filter_is_url(value: str) -> bool:
+    return bool(urlparse(value).scheme)
+
+
 def get_path() -> str:
    """Get the path to the templates directory.

@@ -25,7 +30,9 @@ def get_env(path: str) -> Environment:
    Returns:
        The Jinja environment.
    """
-    return Environment(loader=FileSystemLoader(path))  # noqa: S701 (we are OK with not auto-escaping)
+    env = Environment(loader=FileSystemLoader(path))  # noqa: S701 (we are OK with not auto-escaping)
+    env.filters.update({"is_url": _filter_is_url})
+    return env


 def get_custom_template(path: str) -> Template:

--- a/src/git_changelog/templates/keepachangelog/commit.md
+++ b/src/git_changelog/templates/keepachangelog/commit.md
@@ -2,3 +2,8 @@
 {%- if commit.text_refs.issues_not_in_subject %} Related issues/PRs: {% for issue in commit.text_refs.issues_not_in_subject -%}
 {% if issue.url %}[{{ issue.ref }}]({{ issue.url }}){% else %}{{ issue.ref }}{% endif %}{% if not loop.last %}, {% endif -%}
 {%- endfor -%}{%- endif -%}
+{%- for trailer_name, trailer_value in commit.trailers.items() -%}
+{%- if trailer_value|is_url %} [{{ trailer_name }}]({{ trailer_value }})
+{%- else %} {{ trailer_name }}: {{ trailer_value }}{% endif %}
+{%- if not loop.last %},{% endif %}
+{%- endfor -%}
--- a/tests/test_commit.py
+++ b/tests/test_commit.py
+"""Tests for the `commit` module."""
+
+import pytest
+
+from git_changelog.commit import Commit
+
+
+@pytest.mark.parametrize(
+    ("body", "expected_trailers"),
+    [
+        ("t1: v1\nt2: v2", {"t1": "v1", "t2": "v2"}),  # ok
+        ("body\n\nt1: v1\nt2: v2", {"t1": "v1", "t2": "v2"}),  # ok
+        ("t1: v1\nt2:v2", {}),  # missing space after colon
+        ("t1: v1\nt2: v2\n\nf", {}),  # trailers not last
+        ("t1: v1\nt2 v2", {}),  # not all trailers
+        ("something: else\n\nt1: v1\nt2: v2", {"t1": "v1", "t2": "v2"}),  # parse footer only
+    ],
+)
+def test_parsing_trailers(body, expected_trailers):
+    """Assert trailers are parsed correctly.
+
+    Parameters:
+        body: A commit message body.
+        expected_trailers: The trailers we expect to be parsed.
+    """
+    commit = Commit(
+        commit_hash="aaaaaaaa",
+        subject="Summary",
+        body=body.split("\n"),
+        parse_trailers=True,
+    )
+    assert commit.trailers == expected_trailers