1 files changed, 91 insertions, 0 deletions
diff --git a/spec/lib/gitlab/middleware/memory_report_spec.rb b/spec/lib/gitlab/middleware/memory_report_spec.rb
new file mode 100644
index 00000000000..e063866b056
--- /dev/null
+++ b/spec/lib/gitlab/middleware/memory_report_spec.rb
@@ -0,0 +1,91 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+require 'memory_profiler'
+
+RSpec.describe Gitlab::Middleware::MemoryReport do
+  let(:app) { proc { |env| [200, { 'Content-Type' => 'text/plain' }, ['Hello world!']] } }
+  let(:middleware) { described_class.new(app) }
+
+  describe '#call' do
+    shared_examples 'returns original response' do
+      it 'returns original response' do
+        expect(MemoryProfiler).not_to receive(:report)
+
+        status, headers, body = middleware.call(env)
+
+        expect(status).to eq(200)
+        expect(headers).to eq({ 'Content-Type' => 'text/plain' })
+        expect(body.first).to eq('Hello world!')
+      end
+
+      it 'does not call the MemoryProfiler' do
+        expect(MemoryProfiler).not_to receive(:report)
+
+        middleware.call(env)
+      end
+    end
+
+    context 'when the Rails environment is not development' do
+      let(:env) { Rack::MockRequest.env_for('/') }
+
+      it_behaves_like 'returns original response'
+    end
+
+    context 'when the Rails environment is development' do
+      before do
+        allow(Rails.env).to receive(:development?).and_return(true)
+      end
+
+      context 'when memory report is not requested' do
+        let(:env) { Rack::MockRequest.env_for('/') }
+
+        it_behaves_like 'returns original response'
+      end
+
+      context 'when memory report is requested' do
+        let(:env) { Rack::MockRequest.env_for('/', params: { 'performance_bar' => 'memory' }) }
+
+        before do
+          allow(env).to receive(:[]).and_call_original
+          allow(app).to receive(:call).and_return(empty_memory_report)
+        end
+
+        let(:empty_memory_report) do
+          report = MemoryProfiler::Results.new
+          report.register_results(MemoryProfiler::StatHash.new, MemoryProfiler::StatHash.new, 1)
+        end
+
+        it 'returns a memory report' do
+          expect(MemoryProfiler).to receive(:report).and_yield
+
+          status, headers, body = middleware.call(env)
+
+          expect(status).to eq(200)
+          expect(headers).to eq({ 'Content-Type' => 'text/plain' })
+          expect(body.first).to include('Total allocated: 0 B')
+        end
+
+        context 'when something goes wrong with creating the report' do
+          before do
+            expect(MemoryProfiler).to receive(:report).and_raise(StandardError, 'something went terribly wrong!')
+          end
+
+          it 'logs the error' do
+            expect(::Gitlab::ErrorTracking).to receive(:track_exception)
+
+            middleware.call(env)
+          end
+
+          it 'returns the error' do
+            status, headers, body = middleware.call(env)
+
+            expect(status).to eq(500)
+            expect(headers).to eq({ 'Content-Type' => 'text/plain' })
+            expect(body.first).to include('Could not generate memory report: something went terribly wrong!')
+          end
+        end
+      end
+    end
+  end
+end