Adds mocked dates to the rotations_list_seciion_spec

Fixes a broken master by ensuring we mock the date
used in our rotations list specs.

Additionally splits the test into 2 sections, one for
the current date being today and the opposite

ee/app/assets/javascripts/oncall_schedules/components/schedule/components/current_day_indicator.vue

@@ -17,5 +17,10 @@ export default {
 </script>
 
 <template>
-  <span v-if="hasToday" :style="getIndicatorStyles()" class="current-day-indicator"></span>
+  <span
+    v-if="hasToday"
+    :style="getIndicatorStyles()"
+    data-testid="current-day-indicator"
+    class="current-day-indicator"
+  ></span>
 </template>

ee/spec/frontend/oncall_schedule/schedule/components/__snapshots__/rotations_list_section_spec.js.snap

 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`RotationsListSectionComponent renders component layout 1`] = `
+exports[`RotationsListSectionComponent when the timeframe includes today renders component layout 1`] = `
 <div
   class="list-section"
 >
@@ -70,6 +70,7 @@ exports[`RotationsListSectionComponent renders component layout 1`] = `
     >
       <span
         class="current-day-indicator"
+        data-testid="current-day-indicator"
         style="left: 7.142857142857143%;"
       />
        

ee/spec/frontend/oncall_schedule/schedule/components/rotations_list_section_spec.js

 import { mount } from '@vue/test-utils';
 import { GlCard } from '@gitlab/ui';
+import { useFakeDate } from 'helpers/fake_date';
 import RotationsListSection from 'ee/oncall_schedules/components/schedule/components/rotations_list_section.vue';
 import CurrentDayIndicator from 'ee/oncall_schedules/components/schedule/components/current_day_indicator.vue';
 import RotationsAssignee from 'ee/oncall_schedules/components/rotations/components/rotation_assignee.vue';
@@ -32,9 +33,10 @@ describe('RotationsListSectionComponent', () => {
     });
   }
 
-  beforeEach(() => {
-    createComponent();
-  });
+  const findTimelineCells = () => wrapper.findAll('[data-testid="timelineCell"]');
+  const findRotationAssignees = () => wrapper.findAllComponents(RotationsAssignee);
+  const findCurrentDayIndicatorContent = () =>
+    wrapper.find('[data-testid="current-day-indicator"]');
 
   afterEach(() => {
     if (wrapper) {
@@ -42,25 +44,44 @@ describe('RotationsListSectionComponent', () => {
     }
   });
 
-  const findTimelineCells = () => wrapper.findAll('[data-testid="timelineCell"]');
-  const findRotationAssignees = () => wrapper.findAllComponents(RotationsAssignee);
+  describe('when the timeframe includes today', () => {
+    beforeEach(() => {
+      useFakeDate(2021, 0, 14);
+      createComponent();
+    });
 
-  it('renders component layout', () => {
-    expect(wrapper.element).toMatchSnapshot();
-  });
+    it('renders component layout', () => {
+      expect(wrapper.element).toMatchSnapshot();
+    });
 
-  it('renders timeline cell items based on timeframe data', () => {
-    expect(findTimelineCells().length).toBe(mockTimeframeWeeks.length);
-  });
+    it('renders the current day indicator if the timeframe includes the current day', () => {
+      expect(findCurrentDayIndicatorContent().exists()).toBe(true);
+    });
+
+    it('renders timeline cell items based on timeframe data', () => {
+      expect(findTimelineCells().length).toBe(mockTimeframeWeeks.length);
+    });
+
+    it('renders current day indicator in the first timeline cell', () => {
+      expect(findTimelineCells().at(0).find(CurrentDayIndicator).exists()).toBe(true);
+    });
 
-  it('renders current day indicator in the first timeline cell', () => {
-    expect(findTimelineCells().at(0).find(CurrentDayIndicator).exists()).toBe(true);
+    it('render the correct amount of rotation assignees with their related information', () => {
+      expect(findRotationAssignees()).toHaveLength(2);
+      expect(findRotationAssignees().at(0).props().assignee.user).toEqual(
+        mockRotations[0].shifts.nodes[0].participant.user,
+      );
+    });
   });
 
-  it('render the correct amount of rotation assignees with their related information', () => {
-    expect(findRotationAssignees()).toHaveLength(2);
-    expect(findRotationAssignees().at(0).props().assignee.user).toEqual(
-      mockRotations[0].shifts.nodes[0].participant.user,
-    );
+  describe('when the timeframe does not include today', () => {
+    beforeEach(() => {
+      useFakeDate(2021, 0, 31);
+      createComponent();
+    });
+
+    it('does not render the current day indicator', () => {
+      expect(findCurrentDayIndicatorContent().exists()).toBe(false);
+    });
   });
 });