1 files changed, 48 insertions, 0 deletions
diff --git a/lib/gitlab/ci/reports/codequality_reports_comparer.rb b/lib/gitlab/ci/reports/codequality_reports_comparer.rb
new file mode 100644
index 00000000000..88e02cd9004
--- /dev/null
+++ b/lib/gitlab/ci/reports/codequality_reports_comparer.rb
@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    module Reports
+      class CodequalityReportsComparer < ReportsComparer
+        def initialize(base_report, head_report)
+          @base_report = base_report || CodequalityReports.new
+          @head_report = head_report
+        end
+
+        def success?
+          head_report.degradations_count == 0
+        end
+
+        def existing_errors
+          strong_memoize(:existing_errors) do
+            base_report.all_degradations & head_report.all_degradations
+          end
+        end
+
+        def new_errors
+          strong_memoize(:new_errors) do
+            fingerprints = head_report.degradations.keys - base_report.degradations.keys
+            head_report.degradations.fetch_values(*fingerprints)
+          end
+        end
+
+        def resolved_errors
+          strong_memoize(:resolved_errors) do
+            fingerprints = base_report.degradations.keys - head_report.degradations.keys
+            base_report.degradations.fetch_values(*fingerprints)
+          end
+        end
+
+        def resolved_count
+          resolved_errors.size
+        end
+
+        def total_count
+          head_report.degradations_count
+        end
+
+        alias_method :errors_count, :total_count
+      end
+    end
+  end
+end