1 files changed, 144 insertions, 0 deletions
diff --git a/spec/support_specs/database/prevent_cross_database_modification_spec.rb b/spec/support_specs/database/prevent_cross_database_modification_spec.rb
new file mode 100644
index 00000000000..4fd55d59db0
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+++ b/spec/support_specs/database/prevent_cross_database_modification_spec.rb
@@ -0,0 +1,144 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'Database::PreventCrossDatabaseModification' do
+  let_it_be(:pipeline, refind: true) { create(:ci_pipeline) }
+  let_it_be(:project, refind: true) { create(:project) }
+
+  shared_examples 'succeessful examples' do
+    context 'outside transaction' do
+      it { expect { run_queries }.not_to raise_error }
+    end
+
+    context 'within transaction' do
+      it do
+        Project.transaction do
+          expect { run_queries }.not_to raise_error
+        end
+      end
+    end
+
+    context 'within nested transaction' do
+      it do
+        Project.transaction(requires_new: true) do
+          Project.transaction(requires_new: true) do
+            expect { run_queries }.not_to raise_error
+          end
+        end
+      end
+    end
+  end
+
+  context 'when CI and other tables are read in a transaction' do
+    def run_queries
+      pipeline.reload
+      project.reload
+    end
+
+    include_examples 'succeessful examples'
+  end
+
+  context 'when only CI data is modified' do
+    def run_queries
+      pipeline.touch
+      project.reload
+    end
+
+    include_examples 'succeessful examples'
+  end
+
+  context 'when other data is modified' do
+    def run_queries
+      pipeline.reload
+      project.touch
+    end
+
+    include_examples 'succeessful examples'
+  end
+
+  describe 'with_cross_database_modification_prevented block' do
+    it 'raises error when CI and other data is modified' do
+      expect do
+        with_cross_database_modification_prevented do
+          Project.transaction do
+            project.touch
+            pipeline.touch
+          end
+        end
+      end.to raise_error /Cross-database data modification queries/
+    end
+  end
+
+  context 'when running tests with prevent_cross_database_modification', :prevent_cross_database_modification do
+    context 'when both CI and other data is modified' do
+      def run_queries
+        project.touch
+        pipeline.touch
+      end
+
+      context 'outside transaction' do
+        it { expect { run_queries }.not_to raise_error }
+      end
+
+      context 'when data modification happens in a transaction' do
+        it 'raises error' do
+          Project.transaction do
+            expect { run_queries }.to raise_error /Cross-database data modification queries/
+          end
+        end
+
+        context 'when data modification happens in nested transactions' do
+          it 'raises error' do
+            Project.transaction(requires_new: true) do
+              project.touch
+              Project.transaction(requires_new: true) do
+                expect { pipeline.touch }.to raise_error /Cross-database data modification queries/
+              end
+            end
+          end
+        end
+      end
+    end
+
+    context 'when CI association is modified through project' do
+      def run_queries
+        project.variables.build(key: 'a', value: 'v')
+        project.save!
+      end
+
+      include_examples 'succeessful examples'
+    end
+
+    describe '#allow_cross_database_modification_within_transaction' do
+      it 'skips raising error' do
+        expect do
+          Gitlab::Database.allow_cross_database_modification_within_transaction(url: 'gitlab-issue') do
+            Project.transaction do
+              pipeline.touch
+              project.touch
+            end
+          end
+        end.not_to raise_error
+      end
+
+      it 'raises error when complex factories are built referencing both databases' do
+        expect do
+          ApplicationRecord.transaction do
+            create(:ci_pipeline)
+          end
+        end.to raise_error /Cross-database data modification queries/
+      end
+
+      it 'skips raising error on factory creation' do
+        expect do
+          Gitlab::Database.allow_cross_database_modification_within_transaction(url: 'gitlab-issue') do
+            ApplicationRecord.transaction do
+              create(:ci_pipeline)
+            end
+          end
+        end.not_to raise_error
+      end
+    end
+  end
+end