add --dry-run option to print latest snippet content instead of updat…

…ing the changelog, closes #27

.snippets/27.md

@@ -0,0 +1,8 @@
+## Dry run option to print latest changelog entry
+<!--
+type: feature
+scope: all
+affected: all
+-->
+
+Use `--dry-run` with the `changelog` subparser to print the latest changelog entry as JSON instead of updating the changelog file.

README.md

@@ -98,6 +98,27 @@ version entries and version bumps multiple times otherwise.*
 changelog-generator changelog changelog.md --snippets=.snippets [--in-place]
 ```
 
+To just get the latest changelog entry without updating or generating the
+changelog, use `--dry-run` to print the latest snippet content in JSON format.
+
+```json
+{
+    "version": "1.5.0",
+    "timestamp": "2024-10-12T13:36:46+02:00",
+    "meta": {
+        "type": "feature",
+        "scope": [
+            "all"
+        ],
+        "affected": [
+            "all"
+        ]
+    },
+    "content": "\n\nUse `--dry-run` with the `changelog` subparser to print the latest changelog entry as JSON instead of updating the changelog file.\n",
+    "version_reference": "https://github.com/brainelectronics/snippets2changelog/tree/1.5.0"
+}
+```
+
 ### Parse
 
 Parse an existing snippet file and return the data as JSON without indentation

snippets2changelog/cli.py

@@ -75,6 +75,11 @@ def parse_args(argv: Union[Sequence[str], None] = None) -> Args:
         action='store_true',
         help="Skip snippets with scope set as 'internal'",
     )
+    parser_changelog.add_argument(
+        "--dry-run",
+        action='store_true',
+        help="Print latest changelog entry as JSON instead of updating the changelog file",
+    )
 
     parser_create = subparsers.add_parser(
         "create",
@@ -125,7 +130,7 @@ def fn_info(_args: Args) -> None:
 
 def fn_changelog(args: Args) -> None:
     cc = ChangelogCreator(changelog=args.changelog, snippets_folder=args.snippets, update_in_place=args.in_place, skip_internal=args.no_internal, verbosity=args.verbose)
-    cc.update_changelog()
+    cc.update_changelog(dry_run=args.dry_run)
 
 
 def fn_create(args: Args) -> None:

snippets2changelog/creator.py

@@ -2,6 +2,7 @@
 
 """Snippets generator"""
 
+import json
 import logging
 from pathlib import Path
 from typing import Dict, Iterator
@@ -89,11 +90,13 @@ def __init__(self, changelog: Path,  snippets_folder: Path, update_in_place: boo
 
         self._skip_internal = skip_internal
 
-    def update_changelog(self) -> None:
+    def update_changelog(self, dry_run: bool = False) -> None:
         new_changelog_content = ""
         # create a "prolog" and an "epilog", with the new content in between
         existing_changelog_content = read_file(path=self._changelog, parse="read").split(self._version_line)
 
+        latest_changelog_entry = {}
+
         for commit, file_name in self.snippets():
             self._logger.debug(f"Parsing {file_name}")
             self.parse(file_name=file_name)
@@ -123,12 +126,18 @@ def update_changelog(self) -> None:
                 "content": snippet_content["details"],
                 "version_reference": f"https://github.com/brainelectronics/snippets2changelog/tree/{self.semver_data}",
             }
+            latest_changelog_entry = changelog_entry_content
             self._logger.debug(f"changelog_entry_content: {changelog_entry_content}")
 
             changelog_entry = self._env.get_template("changelog_part.md.template").render(changelog_entry_content)
             self._logger.debug(f"rendered changelog_entry: \n{changelog_entry}")
             new_changelog_content = changelog_entry + new_changelog_content
 
+        if dry_run:
+            latest_changelog_entry['version'] = str(latest_changelog_entry['version'])
+            print(json.dumps(latest_changelog_entry))
+            return
+
         rendered_changelog = self._env.get_template("changelog.md.template").render({"prolog": existing_changelog_content[0], "new": new_changelog_content, "existing": self._version_line + existing_changelog_content[1]})
         rendered_changelog_path = Path(f"{self._changelog}")
         if not self._update_in_place: