Merge branch 'nicolasdular/snowplow-spec-helper' into 'master'

Add snowplow spec helper

See merge request gitlab-org/gitlab!40748

doc/development/testing_guide/best_practices.md

@@ -524,6 +524,48 @@ for modifications. If you have no other choice, an `around` block similar to the
 example for global variables, above, can be used, but this should be avoided if
 at all possible.
 
+#### Test Snowplow events
+
+CAUTION: **Warning:**
+Snowplow performs **runtime type checks** by using the [contracts gem](https://rubygems.org/gems/contracts).
+Since Snowplow is **by default disabled in tests and development**, it can be hard to
+**catch exceptions** when mocking `Gitlab::Tracking`.
+
+To catch runtime errors due to type checks, you can enable Snowplow in tests by marking the spec with
+`:snowplow` and use the `expect_snowplow_event` helper which will check for
+calls to `Gitlab::Tracking#event`.
+
+```ruby
+describe '#show', :snowplow do
+  it 'tracks snowplow events' do
+    get :show
+
+    expect_snowplow_event(
+      category: 'Experiment',
+      action: 'start',
+    )
+    expect_snowplow_event(
+      category: 'Experiment',
+      action: 'sent',
+      property: 'property',
+      label: 'label'
+    )
+  end
+end
+```
+
+When you want to ensure that no event got called, you can use `expect_no_snowplow_event`.
+
+```ruby
+  describe '#show', :snowplow do
+    it 'does not track any snowplow events' do
+      get :show
+
+      expect_no_snowplow_event
+    end
+  end
+```
+
 ### Table-based / Parameterized tests
 
 This style of testing is used to exercise one piece of code with a comprehensive

lib/gitlab/tracking.rb

@@ -56,12 +56,19 @@ module Gitlab
 
       def snowplow
         @snowplow ||= SnowplowTracker::Tracker.new(
-          SnowplowTracker::AsyncEmitter.new(Gitlab::CurrentSettings.snowplow_collector_hostname, protocol: 'https'),
+          emitter,
           SnowplowTracker::Subject.new,
           SNOWPLOW_NAMESPACE,
           Gitlab::CurrentSettings.snowplow_app_id
         )
       end
+
+      def emitter
+        SnowplowTracker::AsyncEmitter.new(
+          Gitlab::CurrentSettings.snowplow_collector_hostname,
+          protocol: 'https'
+        )
+      end
     end
   end
 end

spec/spec_helper.rb

@@ -115,6 +115,7 @@ RSpec.configure do |config|
   config.include StubExperiments
   config.include StubGitlabCalls
   config.include StubGitlabData
+  config.include SnowplowHelpers
   config.include NextFoundInstanceOf
   config.include NextInstanceOf
   config.include TestEnv

spec/support/helpers/snowplow_helpers.rb

+# frozen_string_literal: true
+
+module SnowplowHelpers
+  # Asserts call for one snowplow event from `Gitlab::Tracking#event`.
+  #
+  # @param [Hash]
+  #
+  # Examples:
+  #
+  #   describe '#show', :snowplow do
+  #     it 'tracks snowplow events' do
+  #       get :show
+  #
+  #       expect_snowplow_event(category: 'Experiment', action: 'start')
+  #     end
+  #   end
+  #
+  #   describe '#create', :snowplow do
+  #     it 'tracks snowplow events' do
+  #       post :create
+  #
+  #       expect_snowplow_event(
+  #         category: 'Experiment',
+  #         action: 'created',
+  #       )
+  #       expect_snowplow_event(
+  #         category: 'Experiment',
+  #         action: 'accepted',
+  #         property: 'property',
+  #         label: 'label'
+  #       )
+  #     end
+  #   end
+  def expect_snowplow_event(category:, action:, **kwargs)
+    expect(Gitlab::Tracking).to have_received(:event)
+      .with(category, action, **kwargs)
+  end
+
+  # Asserts that no call to `Gitlab::Tracking#event` was made.
+  #
+  # Example:
+  #
+  #   describe '#show', :snowplow do
+  #     it 'does not track any snowplow events' do
+  #       get :show
+  #
+  #       expect_no_snowplow_event
+  #     end
+  #   end
+  def expect_no_snowplow_event
+    expect(Gitlab::Tracking).not_to have_received(:event)
+  end
+end

spec/support/snowplow.rb

+# frozen_string_literal: true
+
+RSpec.configure do |config|
+  config.before(:each, :snowplow) do
+    # Using a high buffer size to not cause early flushes
+    buffer_size = 100
+    # WebMock is set up to allow requests to `localhost`
+    host = 'localhost'
+
+    allow(Gitlab::Tracking)
+      .to receive(:emitter)
+      .and_return(SnowplowTracker::Emitter.new(host, buffer_size: buffer_size))
+
+    stub_application_setting(snowplow_enabled: true)
+
+    allow(Gitlab::Tracking).to receive(:event).and_call_original
+  end
+
+  config.after(:each, :snowplow) do
+    Gitlab::Tracking.send(:snowplow).flush
+  end
+end