1 files changed, 140 insertions, 0 deletions
diff --git a/spec/scripts/pipeline/average_reports_spec.rb b/spec/scripts/pipeline/average_reports_spec.rb
new file mode 100644
index 00000000000..2eee8d34fd5
--- /dev/null
+++ b/spec/scripts/pipeline/average_reports_spec.rb
@@ -0,0 +1,140 @@
+# frozen_string_literal: true
+
+require 'fast_spec_helper'
+require 'tempfile'
+require 'json'
+require_relative '../../../scripts/pipeline/average_reports'
+
+RSpec.describe AverageReports, feature_category: :tooling do
+  let(:initial_report) do
+    {
+      'spec/frontend/fixtures/analytics.rb' => 1,
+      'spec/frontend/fixtures/runner_instructions.rb' => 0.8074841039997409,
+      'ee/spec/frontend/fixtures/analytics/value_streams_test_stage.rb' => 50.35115972699987,
+      'ee/spec/frontend/fixtures/merge_requests.rb' => 19.16644390500005,
+      'old' => 123
+    }
+  end
+
+  let(:new_report) do
+    {
+      'spec/frontend/fixtures/analytics.rb' => 2,
+      'spec/frontend/fixtures/runner_instructions.rb' => 0,
+      'ee/spec/frontend/fixtures/analytics/value_streams_test_stage.rb' => 0,
+      'ee/spec/frontend/fixtures/merge_requests.rb' => 0,
+      'new' => 234
+    }
+  end
+
+  let(:new_report_2) do
+    {
+      'spec/frontend/fixtures/analytics.rb' => 3,
+      'new' => 468
+    }
+  end
+
+  let(:initial_report_file) do
+    Tempfile.new('temp_initial_report.json').tap do |f|
+      # rubocop:disable Gitlab/Json
+      f.write(JSON.dump(initial_report))
+      # rubocop:enable Gitlab/Json
+      f.close
+    end
+  end
+
+  let(:new_report_file_1) do |_f|
+    Tempfile.new('temp_new_report1.json').tap do |f|
+      # rubocop:disable Gitlab/Json
+      f.write(JSON.dump(new_report))
+      # rubocop:enable Gitlab/Json
+      f.close
+    end
+  end
+
+  let(:new_report_file_2) do |_f|
+    Tempfile.new('temp_new_report2.json').tap do |f|
+      # rubocop:disable Gitlab/Json
+      f.write(JSON.dump(new_report_2))
+      # rubocop:enable Gitlab/Json
+      f.close
+    end
+  end
+
+  before do
+    allow(subject).to receive(:puts)
+  end
+
+  after do
+    initial_report_file.unlink
+    new_report_file_1.unlink
+    new_report_file_2.unlink
+  end
+
+  describe 'execute' do
+    context 'with 1 new report' do
+      subject do
+        described_class.new(
+          initial_report_file: initial_report_file.path,
+          new_report_files: [new_report_file_1.path]
+        )
+      end
+
+      it 'returns average durations' do
+        results = subject.execute
+
+        expect(results['spec/frontend/fixtures/analytics.rb']).to be_within(0.01).of(1.5)
+        expect(results['spec/frontend/fixtures/runner_instructions.rb']).to be_within(0.01).of(0.4)
+        expect(results['ee/spec/frontend/fixtures/analytics/value_streams_test_stage.rb']).to be_within(0.01).of(25.17)
+        expect(results['ee/spec/frontend/fixtures/merge_requests.rb']).to be_within(0.01).of(9.58)
+        expect(results['new']).to be_within(0.01).of(234)
+
+        # excludes entry missing from the new report
+        expect(results['old']).to be_nil
+      end
+    end
+
+    context 'with 2 new reports' do
+      subject do
+        described_class.new(
+          initial_report_file: initial_report_file.path,
+          new_report_files: [new_report_file_1.path, new_report_file_2.path]
+        )
+      end
+
+      it 'returns average durations' do
+        results = subject.execute
+
+        expect(subject).to have_received(:puts).with("Updating #{initial_report_file.path} with 2 new reports...")
+        expect(subject).to have_received(:puts).with("Updated 5 data points from #{new_report_file_1.path}")
+        expect(subject).to have_received(:puts).with("Updated 2 data points from #{new_report_file_2.path}")
+
+        expect(results['spec/frontend/fixtures/analytics.rb']).to be_within(0.01).of(2)
+        expect(results['new']).to be_within(0.01).of(351)
+
+        # retains entry present in one of the new reports
+        expect(results['spec/frontend/fixtures/runner_instructions.rb']).to be_within(0.01).of(0.4)
+        expect(results['ee/spec/frontend/fixtures/analytics/value_streams_test_stage.rb']).to be_within(0.01).of(25.17)
+        expect(results['ee/spec/frontend/fixtures/merge_requests.rb']).to be_within(0.01).of(9.58)
+
+        # excludes entry missing from both of the new reports
+        expect(results['old']).to be_nil
+      end
+    end
+
+    context 'when some of the new report files do not exist' do
+      subject do
+        described_class.new(
+          initial_report_file: initial_report_file.path,
+          new_report_files: [new_report_file_1.path, 'file_does_not_exist.json']
+        )
+      end
+
+      it 'ignores the nil file and only process 1 new report' do
+        subject.execute
+
+        expect(subject).to have_received(:puts).with("Updating #{initial_report_file.path} with 1 new reports...")
+        expect(subject).to have_received(:puts).with("Updated 5 data points from #{new_report_file_1.path}")
+      end
+    end
+  end
+end