fix(changelog): do not change the tag date if tag already exists (#861)

* fix(changelog): do not change the tag date if it already exists

* fix: fix logic

* refactor: revert the assignment

.github/fixtures/test-unchanged-tag-date/cliff.toml

@@ -0,0 +1,34 @@
+[changelog]
+# template for the changelog footer
+header = """
+# Changelog\n
+All notable changes to this project will be documented in this file.\n
+"""
+# template for the changelog body
+# https://keats.github.io/tera/docs/#introduction
+body = """
+{% if version %}\
+    ## [{{ version | trim_start_matches(pat="v") }}] - {{ timestamp | date(format="%Y-%m-%d") }}
+{% else %}\
+    ## [unreleased]
+{% endif %}\
+{% for group, commits in commits | group_by(attribute="group") %}
+    ### {{ group | upper_first }}
+    {% for commit in commits %}
+        - {{ commit.message | upper_first }}\
+    {% endfor %}
+{% endfor %}\n
+"""
+# template for the changelog footer
+footer = """
+<!-- generated by git-cliff -->
+"""
+# remove the leading and trailing whitespace from the templates
+trim = true
+
+[git]
+# regex for parsing and grouping commits
+commit_parsers = [
+    { message = "^feat", group = "Features", default_scope = "app" },
+    { message = "^fix", group = "Bug Fixes", scope = "cli" },
+]

.github/fixtures/test-unchanged-tag-date/commit.sh

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+set -e
+
+GIT_COMMITTER_DATE="2022-04-06 01:25:08" git commit --allow-empty -m "Initial commit"
+GIT_COMMITTER_DATE="2022-04-06 01:25:09" git commit --allow-empty -m "feat: add feature 1"
+GIT_COMMITTER_DATE="2022-04-06 01:25:10" git commit --allow-empty -m "fix: fix feature 1"
+git tag v0.1.0
+GIT_COMMITTER_DATE="2022-04-06 01:25:11" git commit --allow-empty -m "feat(gui): add feature 2"
+GIT_COMMITTER_DATE="2022-04-06 01:25:12" git commit --allow-empty -m "fix(gui): fix feature 2"
+git tag v0.2.0

.github/fixtures/test-unchanged-tag-date/expected.md

@@ -0,0 +1,25 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+## [0.2.0] - 2022-04-06
+
+### Bug Fixes
+
+- Fix feature 2
+
+### Features
+
+- Add feature 2
+
+## [0.1.0] - 2022-04-06
+
+### Bug Fixes
+
+- Fix feature 1
+
+### Features
+
+- Add feature 1
+
+<!-- generated by git-cliff -->

.github/workflows/test-fixtures.yml

@@ -93,6 +93,8 @@ jobs:
             command: --bump --unreleased --with-tag-message "Some text"
           - fixtures-name: test-from-context
             command: --from-context context.json
+          - fixtures-name: test-unchanged-tag-date
+            command: --tag v0.2.0
 
     steps:
       - name: Checkout

git-cliff/src/lib.rs

@@ -235,11 +235,13 @@ fn process_repository<'a>(
 	}
 
 	// Update tags.
+	let mut tag_timestamp = None;
 	if let Some(ref tag) = args.tag {
 		if let Some(commit_id) = commits.first().map(|c| c.id().to_string()) {
 			match tags.get(&commit_id) {
 				Some(tag) => {
 					warn!("There is already a tag ({}) for {}", tag.name, commit_id);
+					tag_timestamp = Some(commits[0].time().seconds());
 				}
 				None => {
 					tags.insert(commit_id, repository.resolve_tag(tag));
@@ -263,10 +265,13 @@ fn process_repository<'a>(
 			release.message = tag.message.clone();
 			release.commit_id = Some(commit_id);
 			release.timestamp = if args.tag.as_deref() == Some(tag.name.as_str()) {
-				SystemTime::now()
-					.duration_since(UNIX_EPOCH)?
-					.as_secs()
-					.try_into()?
+				match tag_timestamp {
+					Some(timestamp) => timestamp,
+					None => SystemTime::now()
+						.duration_since(UNIX_EPOCH)?
+						.as_secs()
+						.try_into()?,
+				}
 			} else {
 				git_commit.time().seconds()
 			};