From 2a44a8f5d5e74004c990d45a19b74025ba15cf78 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Romain=20Tarti=C3=A8re?= <romain@blogreen.org>
Date: Mon, 28 Dec 2020 08:03:46 -1000
Subject: [PATCH] Use UTC for future release date

When using future releases, the current local date is writen in the
generated CHANGELOG.  This is usualy done as part of releasing a new
version, that is a few seconds before a that version is tagged and
that tag is pushed to GitHub.

On next version bump, that previous tag exist and it's date is read from
GitHub which provide this information in Coordinated Universal Time
(UTC).

Depending on the time-zone of the user, the date of these two Ruby Time
objects may be different, leading to an unexpected change in the
previous entry of the CHANGELOG.

To avoid this, convert the local time to UTC when we do not have an
actual tag time to use.
---
 Gemfile.lock                                  |  1 +
 .../generator/generator_tags.rb               |  2 +-
 spec/unit/generator/generator_tags_spec.rb    | 27 +++++++++++++++++++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/Gemfile.lock b/Gemfile.lock
index ecade4e01..0d5583ad6 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -3,6 +3,7 @@ PATH
   specs:
     github_changelog_generator (1.15.2)
       activesupport
+      async (>= 1.25.0)
       async-http-faraday
       faraday-http-cache
       multi_json
diff --git a/lib/github_changelog_generator/generator/generator_tags.rb b/lib/github_changelog_generator/generator/generator_tags.rb
index 3e0da72d5..e5959b4eb 100644
--- a/lib/github_changelog_generator/generator/generator_tags.rb
+++ b/lib/github_changelog_generator/generator/generator_tags.rb
@@ -83,7 +83,7 @@ def get_time_of_tag(tag_name)
     # @return [Array] link, name and time of the tag
     def detect_link_tag_time(newer_tag)
       # if tag is nil - set current time
-      newer_tag_time = newer_tag.nil? ? Time.new : get_time_of_tag(newer_tag)
+      newer_tag_time = newer_tag.nil? ? Time.new.getutc : get_time_of_tag(newer_tag)
 
       # if it's future release tag - set this value
       if newer_tag.nil? && options[:future_release]
diff --git a/spec/unit/generator/generator_tags_spec.rb b/spec/unit/generator/generator_tags_spec.rb
index 42764afe0..cd6da3e86 100644
--- a/spec/unit/generator/generator_tags_spec.rb
+++ b/spec/unit/generator/generator_tags_spec.rb
@@ -13,6 +13,33 @@ def tags_from_strings(tags_strings)
     end
   end
 
+  describe "#detect_link_tag_time" do
+    let(:newer_tag) { nil }
+
+    let(:default_options) { GitHubChangelogGenerator::Parser.default_options.merge(verbose: false) }
+    let(:options) do
+      {
+        future_release: "2.0.0"
+      }
+    end
+    let(:generator) { described_class.new(default_options.merge(options)) }
+
+    subject do
+      generator.detect_link_tag_time(newer_tag)
+    end
+
+    context "When the local date is not the same as the UTC date" do
+      before do
+        # 2020-12-27T17:00:00-10:00 is 2020-12-28T03:00:00Z.
+        # GitHub API date & time use UTC, so this instant when converted as a
+        # date should be 2020-12-28.
+        expect(Time).to receive(:new).and_return(Time.new(2020, 12, 27, 17, 0, 0, "-10:00"))
+      end
+
+      it { is_expected.to eq(["2.0.0", "2.0.0", Time.gm(2020, 12, 28, 3)]) }
+    end
+  end
+
   describe "#tag_section_mapping" do
     let(:all_tags) { tags_from_strings(%w[8 7 6 5 4 3 2 1]) }
     let(:sorted_tags) { all_tags }