1 files changed, 53 insertions, 0 deletions
diff --git a/spec/lib/peek/views/memory_spec.rb b/spec/lib/peek/views/memory_spec.rb
new file mode 100644
index 00000000000..1f88aadfc54
--- /dev/null
+++ b/spec/lib/peek/views/memory_spec.rb
@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Peek::Views::Memory, :request_store do
+  subject! { described_class.new }
+
+  before do
+    stub_memory_instrumentation
+  end
+
+  context 'with process_action.action_controller notification' do
+    it 'returns empty results when it has not yet fired' do
+      expect(subject.results).to eq({})
+    end
+
+    it 'returns memory instrumentation data when it has fired' do
+      publish_notification
+
+      expect(subject.results[:calls]).to eq('2 MB')
+      expect(subject.results[:details]).to all(have_key(:item_header))
+      expect(subject.results[:details]).to all(have_key(:item_content))
+      expect(subject.results[:summary]).to include('Objects allocated' => '200 k')
+      expect(subject.results[:summary]).to include('Allocator calls' => '500')
+      expect(subject.results[:summary]).to include('Large allocations' => '1 KB')
+    end
+  end
+
+  def stub_memory_instrumentation
+    start_memory = {
+      total_malloc_bytes: 1,
+      total_mallocs: 2,
+      total_allocated_objects: 3
+    }
+    allow(Gitlab::Memory::Instrumentation).to receive(:start_thread_memory_allocations).and_return(start_memory)
+    allow(Gitlab::Memory::Instrumentation).to receive(:measure_thread_memory_allocations).with(start_memory).and_return({
+      mem_total_bytes: 2_097_152,
+      mem_bytes: 1024,
+      mem_mallocs: 500,
+      mem_objects: 200_000
+    })
+    Gitlab::InstrumentationHelper.init_instrumentation_data
+  end
+
+  def publish_notification
+    headers = double
+    allow(headers).to receive(:env).and_return('action_dispatch.request_id': 'req-42')
+
+    ActiveSupport::Notifications.publish(
+      'process_action.action_controller', Time.current - 1.second, Time.current, 'id', headers: headers
+    )
+  end
+end