1 files changed, 58 insertions, 0 deletions
diff --git a/spec/lib/gitlab/ci/reports/codequality_mr_diff_spec.rb b/spec/lib/gitlab/ci/reports/codequality_mr_diff_spec.rb
new file mode 100644
index 00000000000..8b177fa7fc1
--- /dev/null
+++ b/spec/lib/gitlab/ci/reports/codequality_mr_diff_spec.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Ci::Reports::CodequalityMrDiff do
+  let(:codequality_report) { Gitlab::Ci::Reports::CodequalityReports.new }
+  let(:degradation_1) { build(:codequality_degradation_1) }
+  let(:degradation_2) { build(:codequality_degradation_2) }
+  let(:degradation_3) { build(:codequality_degradation_3) }
+
+  describe '#initialize!' do
+    subject(:report) { described_class.new(codequality_report) }
+
+    context 'when quality has degradations' do
+      context 'with several degradations on the same line' do
+        before do
+          codequality_report.add_degradation(degradation_1)
+          codequality_report.add_degradation(degradation_2)
+        end
+
+        it 'generates quality report for mr diff' do
+          expect(report.files).to match(
+            "file_a.rb" => [
+              { line: 10, description: "Avoid parameter lists longer than 5 parameters. [12/5]", severity: "major" },
+              { line: 10, description: "Method `new_array` has 12 arguments (exceeds 4 allowed). Consider refactoring.", severity: "major" }
+            ]
+          )
+        end
+      end
+
+      context 'with several degradations on several files' do
+        before do
+          codequality_report.add_degradation(degradation_1)
+          codequality_report.add_degradation(degradation_2)
+          codequality_report.add_degradation(degradation_3)
+        end
+
+        it 'returns quality report for mr diff' do
+          expect(report.files).to match(
+            "file_a.rb" => [
+              { line: 10, description: "Avoid parameter lists longer than 5 parameters. [12/5]", severity: "major" },
+              { line: 10, description: "Method `new_array` has 12 arguments (exceeds 4 allowed). Consider refactoring.", severity: "major" }
+            ],
+            "file_b.rb" => [
+              { line: 10, description: "Avoid parameter lists longer than 5 parameters. [12/5]", severity: "minor" }
+            ]
+          )
+        end
+      end
+    end
+
+    context 'when quality has no degradation' do
+      it 'returns an empty hash' do
+        expect(report.files).to match({})
+      end
+    end
+  end
+end