Format timestamp data in pipeline charts

This is a follow-up fix to an issue introduced by the changes
in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/47069

Without formatting the timestamp datatypes returned by the
database, the lookup of each day can fail if GitLab is
configured to run with a Rails time_zone set to anything
non-UTC.

This happens due to the use of Date/Time objects for hash
lookups, which are influenced by the global Rails
configuration and produce a timezoned object that does not
equate with the same time in UTC.

Tests added here fail without the fix, displaying an all zero
data for the chart.

Fixes issue https://gitlab.com/gitlab-org/gitlab/-/issues/296451

changelogs/unreleased/eliminate-tz-sensitivity-ci-analytics-charts.yml

+---
+title: Fix empty pipeline analytics charts when time_zone is non-UTC
+merge_request:
+author:
+type: fixed

lib/gitlab/ci/charts.rb

@@ -31,9 +31,10 @@ module Gitlab
 
           current = @from
           while current <= @to
-            @labels  << current.strftime(@format)
-            @total   << (totals_count[current] || 0)
-            @success << (success_count[current] || 0)
+            label = current.strftime(@format)
+            @labels  << label
+            @total   << (totals_count[label] || 0)
+            @success << (success_count[label] || 0)
 
             current += interval_step
           end
@@ -45,6 +46,7 @@ module Gitlab
           query
             .group("date_trunc('#{interval}', #{::Ci::Pipeline.table_name}.created_at)")
             .count(:created_at)
+            .transform_keys { |date| date.strftime(@format) }
         end
         # rubocop: enable CodeReuse/ActiveRecord
 

spec/lib/gitlab/ci/charts_spec.rb

@@ -47,6 +47,10 @@ RSpec.describe Gitlab::Ci::Charts do
 
     subject { chart.to }
 
+    before do
+      create(:ci_empty_pipeline, project: project, duration: 120)
+    end
+
     it 'includes the whole current day' do
       is_expected.to eq(Date.today.end_of_day)
     end
@@ -58,6 +62,37 @@ RSpec.describe Gitlab::Ci::Charts do
     it 'uses %d %B as labels format' do
       expect(chart.labels).to include(chart.from.strftime('%d %B'))
     end
+
+    it 'returns count of pipelines run each day in the current week' do
+      expect(chart.total).to contain_exactly(0, 0, 0, 0, 0, 0, 0, 1)
+    end
+  end
+
+  context 'weekchart_non_utc' do
+    today = Date.today
+    end_of_today = Time.use_zone(Time.find_zone('Asia/Dubai')) { today.end_of_day }
+
+    let(:project) { create(:project) }
+    let(:chart) do
+      allow(Date).to receive(:today).and_return(today)
+      allow(today).to receive(:end_of_day).and_return(end_of_today)
+      Gitlab::Ci::Charts::WeekChart.new(project)
+    end
+
+    subject { chart.total }
+
+    before do
+      create(:ci_empty_pipeline, project: project, duration: 120)
+    end
+
+    it 'uses a non-utc time zone for range times' do
+      expect(chart.to.zone).to eq(end_of_today.zone)
+      expect(chart.from.zone).to eq(end_of_today.zone)
+    end
+
+    it 'returns count of pipelines run each day in the current week' do
+      is_expected.to contain_exactly(0, 0, 0, 0, 0, 0, 0, 1)
+    end
   end
 
   context 'pipeline_times' do