Add useFixturesFakeDate helper function

- This simply wraps useFakeDate but
  encapsualtes the args

ee/spec/frontend/projects/pipelines/charts/components/deployment_frequency_charts_spec.js

@@ -2,7 +2,7 @@ import { GlSprintf, GlLink } from '@gitlab/ui';
 import * as Sentry from '@sentry/browser';
 import { shallowMount } from '@vue/test-utils';
 import MockAdapter from 'axios-mock-adapter';
-import { useFakeDate } from 'helpers/fake_date';
+import { useFixturesFakeDate } from 'helpers/fake_date';
 import createFlash from '~/flash';
 import axios from '~/lib/utils/axios_utils';
 import httpStatus from '~/lib/utils/http_status';
@@ -21,8 +21,7 @@ const last90DaysData = getJSONFixture(
 );
 
 describe('ee_component/projects/pipelines/charts/components/deployment_frequency_charts.vue', () => {
-  // Set the current Date to the same value that is used when generating the fixtures
-  useFakeDate(2015, 6, 3, 10);
+  useFixturesFakeDate();
 
   let DeploymentFrequencyCharts;
 

spec/frontend/__helpers__/fake_date/fixtures.js

+import { useFakeDate } from './jest';
+
+// Also see spec/support/helpers/javascript_fixtures_helpers.rb
+export const useFixturesFakeDate = () => useFakeDate(2015, 6, 3, 10);

spec/frontend/__helpers__/fake_date/index.js

 export * from './fake_date';
 export * from './jest';
+export * from './fixtures';

spec/support/helpers/javascript_fixtures_helpers.rb

@@ -12,6 +12,7 @@ module JavaScriptFixturesHelpers
   included do |base|
     base.around do |example|
       # pick an arbitrary date from the past, so tests are not time dependent
+      # Also see spec/frontend/__helpers__/fake_date/jest.js
       Timecop.freeze(Time.utc(2015, 7, 3, 10)) { example.run }
 
       raise NoMethodError.new('You need to set `response` for the fixture generator! This will automatically happen with `type: :controller` or `type: :request`.', 'response') unless respond_to?(:response)