feat(template): add changelog --export-template command

commitizen/changelog.py

@@ -37,6 +37,7 @@
     Environment,
     FileSystemLoader,
     PackageLoader,
+    Template,
 )
 
 from commitizen import defaults
@@ -147,17 +148,26 @@ def order_changelog_tree(tree: Iterable, change_type_order: List[str]) -> Iterab
     return sorted_tree
 
 
+def get_changelog_template(
+    loader: Optional[BaseLoader] = None, template: Optional[str] = None
+) -> Template:
+    loader = ChoiceLoader(
+        [
+            FileSystemLoader("."),
+            loader or PackageLoader("commitizen", "templates"),
+        ]
+    )
+    env = Environment(loader=loader, trim_blocks=True)
+    return env.get_template(template or DEFAULT_TEMPLATE)
+
+
 def render_changelog(
     tree: Iterable,
     loader: Optional[BaseLoader] = None,
     template: Optional[str] = None,
     **kwargs,
 ) -> str:
-    loader = ChoiceLoader(
-        [FileSystemLoader("."), loader or PackageLoader("commitizen", "templates")]
-    )
-    env = Environment(loader=loader, trim_blocks=True)
-    jinja_template = env.get_template(template or DEFAULT_TEMPLATE)
+    jinja_template = get_changelog_template(loader, template or DEFAULT_TEMPLATE)
     changelog: str = jinja_template.render(tree=tree, **kwargs)
     return changelog
 

commitizen/cli.py

@@ -293,6 +293,11 @@ def __call__(self, parser, namespace, kwarg, option_string=None):
                             "If not set, it will generate changelog from the start"
                         ),
                     },
+                    {
+                        "name": "--export-template",
+                        "default": None,
+                        "help": "Export the changelog template into this file instead of rendering it",
+                    },
                     *deepcopy(tpl_arguments),
                 ],
             },

commitizen/commands/changelog.py

@@ -1,6 +1,7 @@
 import os.path
 from difflib import SequenceMatcher
 from operator import itemgetter
+from pathlib import Path
 from typing import Callable, Dict, List, Optional
 
 from commitizen import bump, changelog, defaults, factory, git, out
@@ -49,8 +50,13 @@ def __init__(self, config: BaseConfig, args):
         self.tag_format = args.get("tag_format") or self.config.settings.get(
             "tag_format"
         )
-        self.template = args.get("template") or self.config.settings.get("template")
+        self.template = (
+            args.get("template")
+            or self.config.settings.get("template")
+            or self.cz.template
+        )
         self.extras = args.get("extras") or {}
+        self.export_template_to = args.get("export_template")
 
     def _find_incremental_rev(self, latest_version: str, tags: List[GitTag]) -> str:
         """Try to find the 'start_rev'.
@@ -102,6 +108,11 @@ def write_changelog(
                 changelog_out = changelog_hook(changelog_out, partial_changelog)
             changelog_file.write(changelog_out)
 
+    def export_template(self):
+        tpl = changelog.get_changelog_template(self.cz.template_loader, self.template)
+        src = Path(tpl.filename)
+        Path(self.export_template_to).write_text(src.read_text())
+
     def __call__(self):
         commit_parser = self.cz.commit_parser
         changelog_pattern = self.cz.changelog_pattern
@@ -113,6 +124,9 @@ def __call__(self):
             Callable
         ] = self.cz.changelog_message_builder_hook
 
+        if self.export_template_to:
+            return self.export_template()
+
         if not changelog_pattern or not commit_parser:
             raise NoPatternMapError(
                 f"'{self.config.settings['name']}' rule does not support changelog"

tests/commands/test_changelog_command.py

@@ -4,8 +4,10 @@
 from textwrap import dedent
 
 import pytest
+from jinja2 import FileSystemLoader
 from pytest_mock import MockFixture
 
+from commitizen import __file__ as commitizen_init
 from commitizen import cli, git
 from commitizen.changelog import DEFAULT_TEMPLATE
 from commitizen.commands.changelog import Changelog
@@ -1089,3 +1091,44 @@ def test_changelog_template_extra_quotes(
 
     changelog = project_root / "CHANGELOG.md"
     assert changelog.read_text() == "no-quote - single quotes - double quotes"
+
+
+def test_export_changelog_template_from_default(
+    mocker: MockFixture,
+    tmp_commitizen_project: Path,
+):
+    project_root = Path(tmp_commitizen_project)
+    target = project_root / "changelog.jinja"
+    src = Path(commitizen_init).parent / "templates" / DEFAULT_TEMPLATE
+
+    args = ["cz", "changelog", "--export-template", str(target)]
+
+    mocker.patch.object(sys, "argv", args)
+    cli.main()
+
+    assert target.exists()
+    assert target.read_text() == src.read_text()
+
+
+def test_export_changelog_template_from_plugin(
+    mocker: MockFixture,
+    tmp_commitizen_project: Path,
+    mock_plugin: BaseCommitizen,
+    tmp_path: Path,
+):
+    project_root = Path(tmp_commitizen_project)
+    target = project_root / "changelog.jinja"
+    filename = "template.jinja"
+    src = tmp_path / filename
+    tpl = "I am a custom template"
+    src.write_text(tpl)
+    mock_plugin.template_loader = FileSystemLoader(tmp_path)
+    mock_plugin.template = filename
+
+    args = ["cz", "changelog", "--export-template", str(target)]
+
+    mocker.patch.object(sys, "argv", args)
+    cli.main()
+
+    assert target.exists()
+    assert target.read_text() == tpl