Merge branch '262860-draw-rotation-to-grid' into 'master'

Add day based rotation to the schedule view

See merge request gitlab-org/gitlab!51330

app/assets/javascripts/lib/utils/datetime_utility.js

@@ -4,6 +4,8 @@ import * as timeago from 'timeago.js';
 import dateFormat from 'dateformat';
 import { languageCode, s__, __, n__ } from '../../locale';
 
+const MILLISECONDS_IN_DAY = 24 * 60 * 60 * 1000;
+
 window.timeago = timeago;
 
 /**
@@ -851,3 +853,45 @@ export const format24HourTimeStringFromInt = (time) => {
   const formatted24HourString = time > 9 ? `${time}:00` : `0${time}:00`;
   return formatted24HourString;
 };
+
+/**
+ * A utility function which checks if two date ranges overlap.
+ *
+ * @param {Object} givenPeriodLeft - the first period to compare.
+ * @param {Object} givenPeriodRight - the second period to compare.
+ * @returns {Object} { overlap: number of days the overlap is present, overlapStartDate: the start date of the overlap in time format, overlapEndDate: the end date of the overlap in time format }
+ * @throws {Error} Uncaught Error: Invalid period
+ *
+ * @example
+ * getOverlappingDaysInPeriods(
+ *   { start: new Date(2021, 0, 11), end: new Date(2021, 0, 13) },
+ *   { start: new Date(2021, 0, 11), end: new Date(2021, 0, 14) }
+ * ) => { daysOverlap: 2, overlapStartDate: 1610323200000, overlapEndDate: 1610496000000 }
+ *
+ */
+export const getOverlappingDaysInPeriods = (givenPeriodLeft = {}, givenPeriodRight = {}) => {
+  const leftStartTime = new Date(givenPeriodLeft.start).getTime();
+  const leftEndTime = new Date(givenPeriodLeft.end).getTime();
+  const rightStartTime = new Date(givenPeriodRight.start).getTime();
+  const rightEndTime = new Date(givenPeriodRight.end).getTime();
+
+  if (!(leftStartTime <= leftEndTime && rightStartTime <= rightEndTime)) {
+    throw new Error(__('Invalid period'));
+  }
+
+  const isOverlapping = leftStartTime < rightEndTime && rightStartTime < leftEndTime;
+
+  if (!isOverlapping) {
+    return { daysOverlap: 0 };
+  }
+
+  const overlapStartDate = Math.max(leftStartTime, rightStartTime);
+  const overlapEndDate = rightEndTime > leftEndTime ? leftEndTime : rightEndTime;
+  const differenceInMs = overlapEndDate - overlapStartDate;
+
+  return {
+    daysOverlap: Math.ceil(differenceInMs / MILLISECONDS_IN_DAY),
+    overlapStartDate,
+    overlapEndDate,
+  };
+};

app/assets/stylesheets/page_bundles/oncall_schedules.scss

@@ -113,8 +113,6 @@ $column-right-gradient: linear-gradient(to right, $gradient-dark-gray 0%, $gradi
     }
 
     .item-label {
-      @include gl-py-4;
-      @include gl-pl-4;
       border-right: $border-style;
       border-bottom: $border-style;
     }

ee/app/assets/javascripts/oncall_schedules/components/rotations/components/rotation_assignee.vue

 <script>
 import { GlToken, GlAvatarLabeled, GlPopover } from '@gitlab/ui';
-import { assigneeScheduleDateStart } from 'ee/oncall_schedules/utils/common_utils';
+import { formatDate } from '~/lib/utils/datetime_utility';
 import { __, sprintf } from '~/locale';
 
 export default {
@@ -10,66 +10,65 @@ export default {
     GlPopover,
   },
   props: {
-    assigneeIndex: {
-      type: Number,
-      required: true,
-    },
     assignee: {
       type: Object,
       required: true,
     },
-    rotationLength: {
-      type: Number,
+    rotationAssigneeStartsAt: {
+      type: String,
       required: true,
     },
-    rotationStartsAt: {
+    rotationAssigneeEndsAt: {
       type: String,
       required: true,
     },
+    rotationAssigneeStyle: {
+      type: Object,
+      required: true,
+    },
   },
   computed: {
     chevronClass() {
       return `gl-bg-data-viz-${this.assignee.colorPalette}-${this.assignee.colorWeight}`;
     },
     startsAt() {
-      const startsAt = assigneeScheduleDateStart(
-        new Date(this.rotationStartsAt),
-        this.rotationLength * 7 * this.assigneeIndex,
-      ).toLocaleString();
-      return sprintf(__('Starts at %{startsAt}'), { startsAt });
+      return sprintf(__('Starts: %{startsAt}'), {
+        startsAt: formatDate(this.rotationAssigneeStartsAt, 'mmmm d, yyyy, hh:mm'),
+      });
     },
     endsAt() {
-      const endsAt = assigneeScheduleDateStart(
-        new Date(this.rotationStartsAt),
-        this.rotationLength * 7 * this.assigneeIndex + this.rotationLength * 7,
-      ).toLocaleString();
-      return sprintf(__('Ends at %{endsAt}'), { endsAt });
+      return sprintf(__('Ends: %{endsAt}'), {
+        endsAt: formatDate(this.rotationAssigneeEndsAt, 'mmmm d, yyyy, hh:mm'),
+      });
     },
   },
 };
 </script>
 
 <template>
-  <div class="gl-w-full gl-mt-3 gl-px-3">
+  <div
+    class="gl-absolute gl-h-7 gl-mt-3 gl-z-index-1 gl-overflow-hidden"
+    :style="rotationAssigneeStyle"
+  >
     <gl-token
-      :id="assignee.user.id"
-      class="gl-w-full gl-align-items-center"
+      :id="assignee.id"
+      class="gl-w-full gl-h-6 gl-align-items-center"
       :class="chevronClass"
       :view-only="true"
     >
       <gl-avatar-labeled
         shape="circle"
         :size="16"
-        :src="assignee.user.avatarUrl"
+        :src="assignee.avatarUrl"
         :label="assignee.user.username"
         :title="assignee.user.username"
       />
     </gl-token>
     <gl-popover
-      :target="assignee.user.id"
+      :target="assignee.id"
       :title="assignee.user.username"
       triggers="hover"
-      placement="left"
+      placement="top"
     >
       <p class="gl-m-0" data-testid="rotation-assignee-starts-at">{{ startsAt }}</p>
       <p class="gl-m-0" data-testid="rotation-assignee-ends-at">{{ endsAt }}</p>

ee/app/assets/javascripts/oncall_schedules/components/schedule/components/preset_weeks/weeks_header_item.vue

@@ -58,7 +58,11 @@ export default {
 
 <template>
   <span class="timeline-header-item">
-    <div :class="timelineHeaderClass" class="item-label" data-testid="timeline-header-label">
+    <div
+      :class="timelineHeaderClass"
+      class="item-label gl-pl-6 gl-py-4"
+      data-testid="timeline-header-label"
+    >
       {{ timelineHeaderLabel }}
     </div>
     <weeks-header-sub-item :timeframe-item="timeframeItem" />

ee/app/assets/javascripts/oncall_schedules/components/schedule/components/preset_weeks/weeks_header_sub_item.vue

 <script>
-import CommonMixin from '../../../../mixins/common_mixin';
+import updateShiftTimeUnitWidthMutation from 'ee/oncall_schedules/graphql/mutations/update_shift_time_unit_width.mutation.graphql';
+import CommonMixin from 'ee/oncall_schedules/mixins/common_mixin';
+import { GlResizeObserverDirective } from '@gitlab/ui';
 
 export default {
+  directives: {
+    GlResizeObserver: GlResizeObserverDirective,
+  },
   mixins: [CommonMixin],
   props: {
     timeframeItem: {
@@ -26,6 +31,9 @@ export default {
       return headerSubItems;
     },
   },
+  mounted() {
+    this.updateShiftStyles();
+  },
   methods: {
     getSubItemValueClass(subItem) {
       // Show dark color text only for current & upcoming dates
@@ -36,15 +44,28 @@ export default {
       }
       return '';
     },
+    updateShiftStyles() {
+      this.$apollo.mutate({
+        mutation: updateShiftTimeUnitWidthMutation,
+        variables: {
+          shiftTimeUnitWidth: this.$refs.weeklyDayCell[0].offsetWidth,
+        },
+      });
+    },
   },
 };
 </script>
 
 <template>
-  <div class="item-sublabel">
+  <div
+    v-gl-resize-observer="updateShiftStyles"
+    class="item-sublabel"
+    data-testid="week-item-sublabel"
+  >
     <span
       v-for="(subItem, index) in headerSubItems"
       :key="index"
+      ref="weeklyDayCell"
       :class="getSubItemValueClass(subItem)"
       class="sublabel-value"
       data-testid="sublabel-value"

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

 <script>
 import { GlButtonGroup, GlButton, GlTooltipDirective, GlModalDirective } from '@gitlab/ui';
+import DeleteRotationModal from 'ee/oncall_schedules/components/rotations/components/delete_rotation_modal.vue';
+import { editRotationModalId, deleteRotationModalId } from 'ee/oncall_schedules/constants';
 import { s__ } from '~/locale';
 import CurrentDayIndicator from './current_day_indicator.vue';
-import RotationAssignee from '../../rotations/components/rotation_assignee.vue';
-import DeleteRotationModal from '../../rotations/components/delete_rotation_modal.vue';
-import { editRotationModalId, deleteRotationModalId } from '../../../constants';
+import ScheduleShift from './schedule_shift.vue';
 
 export const i18n = {
   editRotationLabel: s__('OnCallSchedules|Edit rotation'),
@@ -19,8 +19,8 @@ export default {
     GlButtonGroup,
     GlButton,
     CurrentDayIndicator,
-    RotationAssignee,
     DeleteRotationModal,
+    ScheduleShift,
   },
   directives: {
     GlModal: GlModalDirective,
@@ -43,12 +43,16 @@ export default {
   data() {
     return {
       rotationToUpdate: {},
+      shiftWidths: 0,
     };
   },
   methods: {
     setRotationToUpdate(rotation) {
       this.rotationToUpdate = rotation;
     },
+    isLastCell(index) {
+      return index + 1 === this.timeframe.length;
+    },
   },
 };
 </script>
@@ -87,15 +91,19 @@ export default {
       <span
         v-for="(timeframeItem, index) in timeframe"
         :key="index"
-        class="timeline-cell"
+        class="timeline-cell gl-border-b-solid gl-border-b-gray-100 gl-border-b-1"
+        :class="{ 'gl-overflow-hidden': isLastCell(index) }"
         data-testid="timelineCell"
       >
         <current-day-indicator :preset-type="presetType" :timeframe-item="timeframeItem" />
-        <rotation-assignee
-          :assignee="rotation.participants.nodes[index]"
-          :assignee-index="index"
-          :rotation-length="rotation.length"
-          :rotation-starts-at="rotation.startsAt"
+        <schedule-shift
+          v-for="(shift, shiftIndex) in rotation.shifts.nodes"
+          :key="shift.startAt"
+          :shift="shift"
+          :shift-index="shiftIndex"
+          :preset-type="presetType"
+          :timeframe-item="timeframeItem"
+          :timeframe="timeframe"
         />
       </span>
     </div>

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

+<script>
+import RotationAssignee from 'ee/oncall_schedules/components/rotations/components/rotation_assignee.vue';
+import {
+  PRESET_TYPES,
+  DAYS_IN_WEEK,
+  DAYS_IN_DATE_WEEK,
+  ASSIGNEE_SPACER,
+} from 'ee/oncall_schedules/constants';
+import getShiftTimeUnitWidthQuery from 'ee/oncall_schedules/graphql/queries/get_shift_time_unit_width.query.graphql';
+import { getOverlappingDaysInPeriods } from '~/lib/utils/datetime_utility';
+import { incrementDateByDays } from '../utils';
+
+export default {
+  components: {
+    RotationAssignee,
+  },
+  props: {
+    shift: {
+      type: Object,
+      required: true,
+    },
+    shiftIndex: {
+      type: Number,
+      required: true,
+    },
+    timeframeItem: {
+      type: [Date, Object],
+      required: true,
+    },
+    timeframe: {
+      type: Array,
+      required: true,
+    },
+    presetType: {
+      type: String,
+      required: true,
+    },
+  },
+  data() {
+    return {
+      shiftTimeUnitWidth: 0,
+    };
+  },
+  apollo: {
+    shiftTimeUnitWidth: {
+      query: getShiftTimeUnitWidthQuery,
+    },
+  },
+  computed: {
+    currentTimeframeEndsAt() {
+      let UnitOfIncrement = 0;
+      if (this.presetType === PRESET_TYPES.WEEKS) {
+        UnitOfIncrement = DAYS_IN_DATE_WEEK;
+      }
+
+      return incrementDateByDays(this.timeframeItem, UnitOfIncrement);
+    },
+    daysUntilEndOfTimeFrame() {
+      return (
+        this.currentTimeframeEndsAt.getDate() -
+        new Date(this.shiftRangeOverlap.overlapStartDate).getDate() +
+        1
+      );
+    },
+    rotationAssigneeStyle() {
+      const startDate = this.shiftStartsAt.getDay();
+      const firstDayOfWeek = this.timeframeItem.getDay();
+      const isFirstCell = startDate === firstDayOfWeek;
+      const left =
+        isFirstCell || this.shiftStartDateOutOfRange
+          ? '0px'
+          : `${
+              (DAYS_IN_WEEK - this.daysUntilEndOfTimeFrame) * this.shiftTimeUnitWidth +
+              ASSIGNEE_SPACER
+            }px`;
+      const width = `${this.shiftTimeUnitWidth * this.shiftWidth}px`;
+
+      return {
+        left,
+        width,
+      };
+    },
+    shiftStartsAt() {
+      return new Date(this.shift.startsAt);
+    },
+    shiftEndsAt() {
+      return new Date(this.shift.endsAt);
+    },
+    shiftStartDateOutOfRange() {
+      return this.shiftStartsAt.getTime() < this.timeframeItem.getTime();
+    },
+    shiftShouldRender() {
+      if (this.timeFrameIndex !== 0) {
+        return (
+          new Date(this.shiftRangeOverlap.overlapStartDate) > this.timeframeItem &&
+          new Date(this.shiftRangeOverlap.overlapStartDate) < this.currentTimeframeEndsAt
+        );
+      }
+
+      return Boolean(this.shiftRangeOverlap.daysOverlap);
+    },
+    shiftRangeOverlap() {
+      try {
+        return getOverlappingDaysInPeriods(
+          { start: this.timeframeItem, end: this.currentTimeframeEndsAt },
+          { start: this.shiftStartsAt, end: this.shiftEndsAt },
+        );
+      } catch (error) {
+        // TODO: We need to decide the UX implications of a invalid date creation.
+        return { daysOverlap: 0 };
+      }
+    },
+    shiftWidth() {
+      const offset = this.shiftStartDateOutOfRange ? 0 : 1;
+      const baseWidth =
+        this.timeFrameIndex === 0
+          ? this.totalShiftRangeOverlap.daysOverlap
+          : this.shiftRangeOverlap.daysOverlap;
+
+      return baseWidth + offset;
+    },
+    timeFrameIndex() {
+      return this.timeframe.indexOf(this.timeframeItem);
+    },
+    timeFrameEndsAt() {
+      return this.timeframe[this.timeframe.length - 1];
+    },
+    totalShiftRangeOverlap() {
+      return getOverlappingDaysInPeriods(
+        {
+          start: this.timeframeItem,
+          end: incrementDateByDays(this.timeFrameEndsAt, DAYS_IN_DATE_WEEK),
+        },
+        { start: this.shiftStartsAt, end: this.shiftEndsAt },
+      );
+    },
+  },
+};
+</script>
+
+<template>
+  <rotation-assignee
+    v-if="shiftShouldRender"
+    :assignee="shift.participant"
+    :rotation-assignee-style="rotationAssigneeStyle"
+    :rotation-assignee-starts-at="shift.startsAt"
+    :rotation-assignee-ends-at="shift.endsAt"
+  />
+</template>

ee/app/assets/javascripts/oncall_schedules/components/schedule/utils.js

@@ -32,3 +32,18 @@ export const getTimeframeForWeeksView = (initialDate = new Date()) => {
 
   return timeframe;
 };
+
+/**
+ * A utility function which extends a given date value by a certain amount of days.
+ *
+ * @param {Date} initial - the initial date to extend.
+ * @param {Number} increment - the amount of days to extend by.
+ * @returns {Date}
+ *
+ * @example
+ * incrementDateByDays(new Date(2021, 0, 10), 6) => new Date(2021, 0, 16)
+ *
+ */
+export const incrementDateByDays = (initial, increment) => {
+  return new Date(new Date().setDate(initial.getDate() + increment));
+};

ee/app/assets/javascripts/oncall_schedules/constants.js

@@ -24,3 +24,9 @@ export const PRESET_DEFAULTS = {
 export const addRotationModalId = 'addRotationModal';
 export const editRotationModalId = 'editRotationModal';
 export const deleteRotationModalId = 'deleteRotationModal';
+
+/**
+ * Used as a JavaScript week is represented as 0 - 6
+ */
+export const DAYS_IN_DATE_WEEK = 6;
+export const ASSIGNEE_SPACER = 2;

ee/app/assets/javascripts/oncall_schedules/graphql.js

 import Vue from 'vue';
 import VueApollo from 'vue-apollo';
+import produce from 'immer';
 import createDefaultClient from '~/lib/graphql';
+import getShiftTimeUnitWidthQuery from './graphql/queries/get_shift_time_unit_width.query.graphql';
 
 Vue.use(VueApollo);
 
+const resolvers = {
+  Mutation: {
+    updateShiftTimeUnitWidth: (_, { shiftTimeUnitWidth = 0 }, { cache }) => {
+      const sourceData = cache.readQuery({ query: getShiftTimeUnitWidthQuery });
+      const data = produce(sourceData, (draftData) => {
+        // eslint-disable-next-line no-param-reassign
+        draftData.shiftTimeUnitWidth = shiftTimeUnitWidth;
+      });
+      cache.writeQuery({ query: getShiftTimeUnitWidthQuery, data });
+    },
+  },
+};
+
 export default new VueApollo({
-  defaultClient: createDefaultClient(
-    {},
-    {
+  defaultClient: createDefaultClient(resolvers, {
     cacheConfig: {},
     assumeImmutableResults: true,
-    },
-  ),
+  }),
 });

ee/app/assets/javascripts/oncall_schedules/graphql/mutations/update_shift_time_unit_width.mutation.graphql

+mutation updateShiftTimeUnitWidth($shiftTimeUnitWidth: Int) {
+  updateShiftTimeUnitWidth(shiftTimeUnitWidth: $shiftTimeUnitWidth) @client
+}

ee/app/assets/javascripts/oncall_schedules/graphql/queries/get_shift_time_unit_width.query.graphql

+query shiftTimeUnitWidth {
+  shiftTimeUnitWidth @client
+}

ee/app/assets/javascripts/oncall_schedules/index.js

 import Vue from 'vue';
 import VueApollo from 'vue-apollo';
 import OnCallSchedulesWrapper from './components/oncall_schedules_wrapper.vue';
+import getShiftTimeUnitWidthQuery from './graphql/queries/get_shift_time_unit_width.query.graphql';
 import apolloProvider from './graphql';
 
 Vue.use(VueApollo);
@@ -12,6 +13,13 @@ export default () => {
 
   const { projectPath, emptyOncallSchedulesSvgPath, timezones } = el.dataset;
 
+  apolloProvider.clients.defaultClient.cache.writeQuery({
+    query: getShiftTimeUnitWidthQuery,
+    data: {
+      shiftTimeUnitWidth: 0,
+    },
+  });
+
   return new Vue({
     el,
     apolloProvider,

ee/app/assets/javascripts/oncall_schedules/utils/common_utils.js

 import { sprintf, __ } from '~/locale';
-import { getDateInFuture } from '~/lib/utils/datetime_utility';
 
 /**
  * Returns formatted timezone string, e.g. (UTC-09:00) AKST Alaska
@@ -18,19 +17,6 @@ export const getFormattedTimezone = (tz) => {
   });
 };
 
-/**
- * Returns formatted date of the rotation assignee
- * based on the rotation start time and length
- *
- * @param {Date} startDate
- * @param {Number} daysToAdd
- *
- * @returns {Date}
- */
-export const assigneeScheduleDateStart = (startDate, daysToAdd) => {
-  return getDateInFuture(startDate, daysToAdd);
-};
-
 /**
  * Returns `true` for non-empty string, otherwise returns `false`
  *

ee/spec/frontend/oncall_schedule/add_edit_schedule_modal_spec.js

@@ -61,9 +61,6 @@ describe('AddScheduleModal', () => {
   }
 
   async function updateSchedule(localWrapper) {
-    await jest.runOnlyPendingTimers();
-    await localWrapper.vm.$nextTick();
-
     localWrapper.find(GlModal).vm.$emit('primary', { preventDefault: jest.fn() });
   }
 

ee/spec/frontend/oncall_schedule/mocks/mock_rotation.json

 [{
     "id": "gid://gitlab/IncidentManagement::OncallRotation/2",
     "name": "Rotation 242",
-    "startsAt": "2020-12-09T09:00:53Z",
+    "startsAt": "2021-01-13T10:04:56.333Z",
     "length": 1,
     "lengthUnit": "WEEKS",
     "participants": {
       "nodes": [
         {
           "user": {
-            "id": "gid://gitlab/User/1",
-            "username": "root",
+            "id": "gid://gitlab/IncidentManagement::OncallParticipant/49",
+            "username": "nora.schaden",
             "avatarUrl": "/url"
           },
           "colorWeight": "500",
           "colorPalette": "blue"
+        }
+      ]
     },
+    "shifts": {
+      "nodes": [
         {
+          "participant": {
+            "id": "gid://gitlab/IncidentManagement::OncallParticipant/49",
+            "colorWeight": "500",
+            "colorPalette": "blue",
+            "user": {
+              "username": "nora.schaden"
+            }
+          },
+          "startsAt": "2021-01-12T10:04:56.333Z",
+          "endsAt": "2021-01-15T10:04:56.333Z"
+        },
+        {
+          "participant": {
+            "id": "gid://gitlab/IncidentManagement::OncallParticipant/232",
+            "colorWeight": "500",
+            "colorPalette": "orange",
             "user": {
-              "id": "gid://gitlab/User/2",
-              "username": "david",
+              "username": "racheal.loving"
+            }
+          },
+          "startsAt": "2021-01-16T10:04:56.333Z",
+          "endsAt": "2021-01-18T10:04:56.333Z"
+        }
+      ]
+    }
+  },
+  {
+    "id": "gid://gitlab/IncidentManagement::OncallRotation/55",
+    "name": "Rotation 242",
+    "startsAt": "2021-01-13T10:04:56.333Z",
+    "length": 1,
+    "lengthUnit": "WEEKS",
+    "participants": {
+      "nodes": [
+        {
+          "user": {
+            "id": "gid://gitlab/IncidentManagement::OncallParticipant/99",
+            "username": "david.oregan",
             "avatarUrl": "/url"
           },
           "colorWeight": "500",
-            "colorPalette": "magenta"
+          "colorPalette": "aqua"
+        }
+      ]
+    },
+    "shifts": {
+      "nodes": [
+        {
+          "participant": {
+            "id": "gid://gitlab/IncidentManagement::OncallParticipant/99",
+            "colorWeight": "500",
+            "colorPalette": "aqua",
+            "user": {
+              "username": "david.oregan"
+            }
+          },
+          "startsAt": "2021-01-14T10:04:56.333Z",
+          "endsAt": "2021-01-20T10:04:56.333Z"
+        },
+        {
+          "participant": {
+            "id": "gid://gitlab/IncidentManagement::OncallParticipant/300",
+            "colorWeight": "500",
+            "colorPalette": "green",
+            "user": {
+              "username": "david.keagan"
+            }
+          },
+          "startsAt": "2021-01-21T10:04:56.333Z",
+          "endsAt": "2021-01-26T10:04:56.333Z"
         }
       ]
     }
@@ -30,29 +97,96 @@
   {
     "id": "gid://gitlab/IncidentManagement::OncallRotation/3",
     "name": "Rotation 244",
-    "startsAt": "2020-12-16T09:00:53Z",
+    "startsAt": "2021-01-06T10:04:56.333Z",
     "length": 1,
     "lengthUnit": "WEEKS",
     "participants": {
       "nodes": [
         {
           "user": {
-            "id": "gid://gitlab/User/3",
-            "username": "root 2",
+            "id": "gid://gitlab/IncidentManagement::OncallParticipant/48",
+            "username": "root",
             "avatarUrl": "/url"
           },
           "colorWeight": "500",
-          "colorPalette": "orange"
+          "colorPalette": "magenta"
+        }
+      ]
+    },
+    "shifts": {
+      "nodes": [
+        {
+          "participant": {
+            "id": "gid://gitlab/IncidentManagement::OncallParticipant/100",
+            "colorWeight": "500",
+            "colorPalette": "magenta",
+            "user": {
+              "username": "root"
+            }
+          },
+          "startsAt": "2021-01-10T10:04:56.333Z",
+          "endsAt": "2021-01-13T10:04:56.333Z"
+        },
+        {
+          "participant": {
+            "id": "gid://gitlab/IncidentManagement::OncallParticipant/109",
+            "colorWeight": "600",
+            "colorPalette": "blue",
+            "user": {
+              "username": "root2"
+            }
           },
+          "startsAt": "2021-01-15T10:04:56.333Z",
+          "endsAt": "2021-01-18T10:04:56.333Z"
+        }
+      ]
+    }
+},
+{
+  "id": "gid://gitlab/IncidentManagement::OncallRotation/5",
+  "name": "Rotation 247",
+  "startsAt": "2021-01-06T10:04:56.333Z",
+  "length": 1,
+  "lengthUnit": "WEEKS",
+  "participants": {
+    "nodes": [
       {
         "user": {
-              "id": "gid://gitlab/User/4",
-              "username": "david 2",
+          "id": "gid://gitlab/IncidentManagement::OncallParticipant/51",
+          "username": "oregand",
           "avatarUrl": "/url"
         },
-            "colorWeight": "500",
-            "colorPalette": "aqua"
+        "colorWeight": "600",
+        "colorPalette": "orange"
+      }
+    ]
+  },
+  "shifts": {
+    "nodes": [
+      {
+        "participant": {
+          "id": "gid://gitlab/IncidentManagement::OncallParticipant/52",
+          "colorWeight": "600",
+          "colorPalette": "orange",
+          "user": {
+            "username": "oregand"
+          }
+        },
+        "startsAt": "2021-01-12T10:04:56.333Z",
+        "endsAt": "2021-01-15T10:04:56.333Z"
+      },
+      {
+        "participant": {
+          "id": "gid://gitlab/IncidentManagement::OncallParticipant/77",
+          "colorWeight": "600",
+          "colorPalette": "aqua",
+          "user": {
+            "username": "sarah.w"
+          }
+        },
+        "startsAt": "2021-01-16T10:04:56.333Z",
+        "endsAt": "2021-01-30T10:04:56.333Z"
       }
     ]
   }
-  }]
+}]
\ No newline at end of file

ee/spec/frontend/oncall_schedule/oncall_schedule_wrapper_spec.js

@@ -11,7 +11,6 @@ import VueApollo from 'vue-apollo';
 import { preExistingSchedule, newlyCreatedSchedule } from './mocks/apollo_mock';
 
 const localVue = createLocalVue();
-localVue.use(VueApollo);
 
 describe('On-call schedule wrapper', () => {
   let wrapper;
@@ -45,6 +44,7 @@ describe('On-call schedule wrapper', () => {
 
   function mountComponentWithApollo() {
     const fakeApollo = createMockApollo([[getOncallSchedulesQuery, getOncallSchedulesQuerySpy]]);
+    localVue.use(VueApollo);
 
     wrapper = shallowMount(OnCallScheduleWrapper, {
       localVue,
@@ -64,7 +64,6 @@ describe('On-call schedule wrapper', () => {
   afterEach(() => {
     if (wrapper) {
       wrapper.destroy();
-      wrapper = null;
     }
   });
 

ee/spec/frontend/oncall_schedule/rotations/components/rotation_assignee_spec.js

@@ -2,26 +2,31 @@ import { shallowMount } from '@vue/test-utils';
 import { GlToken, GlAvatarLabeled, GlPopover } from '@gitlab/ui';
 import RotationAssignee from 'ee/oncall_schedules/components/rotations/components/rotation_assignee.vue';
 import { extendedWrapper } from 'helpers/vue_test_utils_helper';
+import { formatDate } from '~/lib/utils/datetime_utility';
 import mockRotations from '../../mocks/mock_rotation.json';
 
 describe('RotationAssignee', () => {
   let wrapper;
 
-  const assignee = mockRotations[0].participants.nodes[1];
-  const findToken = () => wrapper.find(GlToken);
-  const findAvatar = () => wrapper.find(GlAvatarLabeled);
-  const findPopOver = () => wrapper.find(GlPopover);
+  const assignee = mockRotations[0].shifts.nodes[0];
+  const findToken = () => wrapper.findComponent(GlToken);
+  const findAvatar = () => wrapper.findComponent(GlAvatarLabeled);
+  const findPopOver = () => wrapper.findComponent(GlPopover);
   const findStartsAt = () => wrapper.findByTestId('rotation-assignee-starts-at');
   const findEndsAt = () => wrapper.findByTestId('rotation-assignee-ends-at');
 
+  const formattedDate = (date) => {
+    return formatDate(date, 'mmmm d, yyyy, hh:mm');
+  };
+
   function createComponent() {
     wrapper = extendedWrapper(
       shallowMount(RotationAssignee, {
         propsData: {
-          assignee,
-          assigneeIndex: 1,
-          rotationLength: mockRotations[0].length,
-          rotationStartsAt: mockRotations[0].startsAt,
+          assignee: assignee.participant,
+          rotationAssigneeStartsAt: assignee.startsAt,
+          rotationAssigneeEndsAt: assignee.endsAt,
+          rotationAssigneeStyle: { left: '0px', width: '100px' },
         },
       }),
     );
@@ -37,26 +42,20 @@ describe('RotationAssignee', () => {
 
   describe('rotation assignee token', () => {
     it('should render an assignee name', () => {
-      expect(findAvatar().attributes('label')).toBe(assignee.user.username);
-    });
-
-    it('should render an assignee avatar', () => {
-      expect(findAvatar().attributes('src')).toBe(assignee.user.avatarUrl);
+      expect(findAvatar().attributes('label')).toBe(assignee.participant.user.username);
     });
 
     it('should render an assignee color based on the chevron skipping color pallette', () => {
       const token = findToken();
       expect(token.classes()).toContain(
-        `gl-bg-data-viz-${assignee.colorPalette}-${assignee.colorWeight}`,
+        `gl-bg-data-viz-${assignee.participant.colorPalette}-${assignee.participant.colorWeight}`,
       );
     });
 
     it('should render an assignee schedule and rotation information in a popover', () => {
-      expect(findPopOver().attributes('target')).toBe(assignee.user.id);
-      // starts at the beginning of the rotation time
-      expect(findStartsAt().text()).toContain('12/16/2020');
-      // ends at the calculated length of the rotation for this user: rotation length * which user index assignee is at
-      expect(findEndsAt().text()).toContain('12/23/2020');
+      expect(findPopOver().attributes('target')).toBe(assignee.participant.id);
+      expect(findStartsAt().text()).toContain(formattedDate(assignee.startsAt));
+      expect(findEndsAt().text()).toContain(formattedDate(assignee.endsAt));
     });
   });
 });

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

@@ -16,72 +16,217 @@ exports[`RotationsListSectionComponent renders component layout 1`] = `
         Rotation 242
       </span>
        
-      <gl-button-group-stub
-        class="gl-px-2"
+      <div
+        class="gl-px-2 btn-group"
+        role="group"
       >
-        <gl-button-stub
+        <button
           aria-label="Edit rotation"
-          buttontextclasses=""
-          category="tertiary"
-          icon="pencil"
-          role="button"
-          size="medium"
-          tabindex="0"
+          class="btn btn-default btn-md gl-button btn-default-tertiary btn-icon"
           title="Edit rotation"
-          variant="default"
+          type="button"
+        >
+          <!---->
+           
+          <svg
+            aria-hidden="true"
+            class="gl-button-icon gl-icon s16"
+            data-testid="pencil-icon"
+          >
+            <use
+              href="#pencil"
             />
+          </svg>
             
-        <gl-button-stub
+          <!---->
+        </button>
+         
+        <button
           aria-label="Delete rotation"
-          buttontextclasses=""
-          category="tertiary"
-          icon="remove"
-          role="button"
-          size="medium"
-          tabindex="0"
+          class="btn btn-default btn-md gl-button btn-default-tertiary btn-icon"
           title="Delete rotation"
-          variant="default"
+          type="button"
+        >
+          <!---->
+           
+          <svg
+            aria-hidden="true"
+            class="gl-button-icon gl-icon s16"
+            data-testid="remove-icon"
+          >
+            <use
+              href="#remove"
             />
-      </gl-button-group-stub>
+          </svg>
+            
+          <!---->
+        </button>
+      </div>
     </span>
      
     <span
-      class="timeline-cell"
+      class="timeline-cell gl-border-b-solid gl-border-b-gray-100 gl-border-b-1"
       data-testid="timelineCell"
     >
-      <current-day-indicator-stub
-        presettype="WEEKS"
-        timeframeitem="Mon Jan 01 2018 00:00:00 GMT+0000 (Greenwich Mean Time)"
+      <span
+        class="current-day-indicator"
+        style="left: 7.142857142857143%;"
       />
        
-      <rotation-assignee-stub
-        assignee="[object Object]"
-        assigneeindex="0"
-        rotationlength="1"
-        rotationstartsat="2020-12-09T09:00:53Z"
-      />
+      <div
+        class="gl-absolute gl-h-7 gl-mt-3 gl-z-index-1 gl-overflow-hidden"
+        style="left: 0px; width: 0px;"
+      >
+        <span
+          class="gl-w-full gl-h-6 gl-align-items-center gl-token gl-token-default-variant gl-bg-data-viz-blue-500"
+          id="gid://gitlab/IncidentManagement::OncallParticipant/49"
+        >
+          <span
+            class="gl-token-content"
+          >
+            <div
+              class="gl-avatar-labeled"
+              shape="circle"
+              size="16"
+              title="nora.schaden"
+            >
+              <div
+                class="gl-avatar gl-avatar-identicon gl-avatar-circle gl-avatar-s16 gl-avatar-identicon-bg1"
+                title="nora.schaden"
+              >
+                
+  
+
+              </div>
+               
+              <div
+                class="gl-avatar-labeled-labels gl-text-left!"
+              >
+                <div
+                  class="gl-display-flex gl-flex-wrap gl-align-items-center gl-text-left! gl-mx-n1 gl-my-n1"
+                >
+                  <span
+                    class="gl-avatar-labeled-label"
+                  >
+                    nora.schaden
                   </span>
+                   
+                </div>
+                 
                 <span
-      class="timeline-cell"
+                  class="gl-avatar-labeled-sublabel"
+                >
+                  
+                </span>
+              </div>
+            </div>
+             
+            <!---->
+          </span>
+        </span>
+         
+        <div
+          class="gl-popover"
+          title="nora.schaden"
+        >
+          <p
+            class="gl-m-0"
+            data-testid="rotation-assignee-starts-at"
+          >
+            Starts: January 12, 2021, 10:01
+          </p>
+           
+          <p
+            class="gl-m-0"
+            data-testid="rotation-assignee-ends-at"
+          >
+            Ends: January 15, 2021, 10:01
+          </p>
+        </div>
+      </div>
+      <div
+        class="gl-absolute gl-h-7 gl-mt-3 gl-z-index-1 gl-overflow-hidden"
+        style="left: 2px; width: 0px;"
+      >
+        <span
+          class="gl-w-full gl-h-6 gl-align-items-center gl-token gl-token-default-variant gl-bg-data-viz-orange-500"
+          id="gid://gitlab/IncidentManagement::OncallParticipant/232"
+        >
+          <span
+            class="gl-token-content"
+          >
+            <div
+              class="gl-avatar-labeled"
+              shape="circle"
+              size="16"
+              title="racheal.loving"
+            >
+              <div
+                class="gl-avatar gl-avatar-identicon gl-avatar-circle gl-avatar-s16 gl-avatar-identicon-bg1"
+                title="racheal.loving"
+              >
+                
+  
+
+              </div>
+               
+              <div
+                class="gl-avatar-labeled-labels gl-text-left!"
+              >
+                <div
+                  class="gl-display-flex gl-flex-wrap gl-align-items-center gl-text-left! gl-mx-n1 gl-my-n1"
+                >
+                  <span
+                    class="gl-avatar-labeled-label"
+                  >
+                    racheal.loving
+                  </span>
+                   
+                </div>
+                 
+                <span
+                  class="gl-avatar-labeled-sublabel"
+                >
+                  
+                </span>
+              </div>
+            </div>
+             
+            <!---->
+          </span>
+        </span>
+         
+        <div
+          class="gl-popover"
+          title="racheal.loving"
+        >
+          <p
+            class="gl-m-0"
+            data-testid="rotation-assignee-starts-at"
+          >
+            Starts: January 16, 2021, 10:01
+          </p>
+           
+          <p
+            class="gl-m-0"
+            data-testid="rotation-assignee-ends-at"
+          >
+            Ends: January 18, 2021, 10:01
+          </p>
+        </div>
+      </div>
+    </span>
+    <span
+      class="timeline-cell gl-border-b-solid gl-border-b-gray-100 gl-border-b-1 gl-overflow-hidden"
       data-testid="timelineCell"
     >
-      <current-day-indicator-stub
-        presettype="WEEKS"
-        timeframeitem="Mon Jan 08 2018 00:00:00 GMT+0000 (Greenwich Mean Time)"
-      />
+      <!---->
        
-      <rotation-assignee-stub
-        assignee="[object Object]"
-        assigneeindex="1"
-        rotationlength="1"
-        rotationstartsat="2020-12-09T09:00:53Z"
-      />
+      <!---->
+      <!---->
     </span>
   </div>
    
-  <delete-rotation-modal-stub
-    modalid="deleteRotationModal"
-    rotation="[object Object]"
-  />
+  <!---->
 </div>
 `;

ee/spec/frontend/oncall_schedule/schedule/components/preset_weeks/weeks_header_sub_item_spec.js

 import { shallowMount } from '@vue/test-utils';
+import { createMockDirective, getBinding } from 'helpers/vue_mock_directive';
 import WeeksHeaderSubItemComponent from 'ee/oncall_schedules/components/schedule/components/preset_weeks/weeks_header_sub_item.vue';
 import { getTimeframeForWeeksView } from 'ee/oncall_schedules/components/schedule/utils';
+import updateShiftTimeUnitWidthMutation from 'ee/oncall_schedules/graphql/mutations/update_shift_time_unit_width.mutation.graphql';
 import { useFakeDate } from 'helpers/fake_date';
+import { extendedWrapper } from 'helpers/vue_test_utils_helper';
 
 describe('WeeksHeaderSubItemComponent', () => {
   let wrapper;
@@ -11,11 +14,21 @@ describe('WeeksHeaderSubItemComponent', () => {
   const mockTimeframeWeeks = getTimeframeForWeeksView(mockTimeframeInitialDate);
 
   function mountComponent({ timeframeItem = mockTimeframeWeeks[0] }) {
-    wrapper = shallowMount(WeeksHeaderSubItemComponent, {
+    wrapper = extendedWrapper(
+      shallowMount(WeeksHeaderSubItemComponent, {
         propsData: {
           timeframeItem,
         },
-    });
+        directives: {
+          GlResizeObserver: createMockDirective(),
+        },
+        mocks: {
+          $apollo: {
+            mutate: jest.fn(),
+          },
+        },
+      }),
+    );
   }
 
   beforeEach(() => {
@@ -25,11 +38,11 @@ describe('WeeksHeaderSubItemComponent', () => {
   afterEach(() => {
     if (wrapper) {
       wrapper.destroy();
-      wrapper = null;
     }
   });
 
   const findSublabelValues = () => wrapper.findAll('[data-testid="sublabel-value"]');
+  const findWeeksHeaderSubItemComponent = () => wrapper.findByTestId('week-item-sublabel');
 
   describe('computed', () => {
     describe('headerSubItems', () => {
@@ -71,5 +84,24 @@ describe('WeeksHeaderSubItemComponent', () => {
         expect.arrayContaining(['label-dark', 'label-bold']),
       );
     });
+
+    it('should store the rendered cell width in Apollo cache via `updateShiftTimeUnitWidthMutation` when mounted', async () => {
+      wrapper.vm.$apollo.mutate.mockResolvedValueOnce({});
+      await wrapper.vm.$nextTick();
+      expect(wrapper.vm.$apollo.mutate).toHaveBeenCalledWith({
+        mutation: updateShiftTimeUnitWidthMutation,
+        variables: {
+          shiftTimeUnitWidth: wrapper.vm.$refs.weeklyDayCell[0].offsetWidth,
+        },
+      });
+      expect(wrapper.vm.$apollo.mutate).toHaveBeenCalledTimes(1);
+    });
+
+    it('should re-calculate cell width inside Apollo cache on page resize', () => {
+      expect(wrapper.vm.$apollo.mutate).toHaveBeenCalledTimes(1);
+      const { value } = getBinding(findWeeksHeaderSubItemComponent().element, 'gl-resize-observer');
+      value();
+      expect(wrapper.vm.$apollo.mutate).toHaveBeenCalledTimes(2);
+    });
   });
 });

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

-import { shallowMount } from '@vue/test-utils';
+import { mount } from '@vue/test-utils';
 import { GlCard } from '@gitlab/ui';
 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';
@@ -9,19 +9,23 @@ import mockRotations from '../../mocks/mock_rotation.json';
 
 describe('RotationsListSectionComponent', () => {
   let wrapper;
-  const mockTimeframeInitialDate = new Date(2018, 0, 1);
+  const mockTimeframeInitialDate = new Date(mockRotations[0].shifts.nodes[0].startsAt);
   const mockTimeframeWeeks = getTimeframeForWeeksView(mockTimeframeInitialDate);
+  const projectPath = 'group/project';
 
   function createComponent({
     presetType = PRESET_TYPES.WEEKS,
     timeframe = mockTimeframeWeeks,
   } = {}) {
-    wrapper = shallowMount(RotationsListSection, {
+    wrapper = mount(RotationsListSection, {
       propsData: {
         presetType,
         timeframe,
         rotations: [mockRotations[0]],
       },
+      provide: {
+        projectPath,
+      },
       stubs: {
         GlCard,
       },
@@ -39,7 +43,7 @@ describe('RotationsListSectionComponent', () => {
   });
 
   const findTimelineCells = () => wrapper.findAll('[data-testid="timelineCell"]');
-  const findRotationAssignees = () => wrapper.findAll(RotationsAssignee);
+  const findRotationAssignees = () => wrapper.findAllComponents(RotationsAssignee);
 
   it('renders component layout', () => {
     expect(wrapper.element).toMatchSnapshot();
@@ -53,10 +57,10 @@ describe('RotationsListSectionComponent', () => {
     expect(findTimelineCells().at(0).find(CurrentDayIndicator).exists()).toBe(true);
   });
 
-  it('render the correct amount of rotation assignees with their name, avatar and color', () => {
+  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].participants.nodes[0].user,
+      mockRotations[0].shifts.nodes[0].participant.user,
     );
   });
 });

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

+import { shallowMount } from '@vue/test-utils';
+import ScheduleShift from 'ee/oncall_schedules/components/schedule/components/schedule_shift.vue';
+import RotationsAssignee from 'ee/oncall_schedules/components/rotations/components/rotation_assignee.vue';
+import { incrementDateByDays } from 'ee/oncall_schedules/components/schedule/utils';
+import { PRESET_TYPES, DAYS_IN_WEEK } from 'ee/oncall_schedules/constants';
+
+const shift = {
+  participant: {
+    id: '1',
+    user: {
+      username: 'nora.schaden',
+    },
+  },
+  startsAt: '2021-01-12T10:04:56.333Z',
+  endsAt: '2021-01-15T10:04:56.333Z',
+};
+
+const CELL_WIDTH = 50;
+const timeframeItem = new Date(2021, 0, 13);
+const timeframe = [timeframeItem, incrementDateByDays(timeframeItem, DAYS_IN_WEEK)];
+
+describe('ee/oncall_schedules/components/schedule/components/schedule_shift.vue', () => {
+  let wrapper;
+
+  function createComponent({ props = {}, data = {} } = {}) {
+    wrapper = shallowMount(ScheduleShift, {
+      propsData: {
+        shift,
+        shiftIndex: 0,
+        timeframeItem,
+        timeframe,
+        presetType: PRESET_TYPES.WEEKS,
+        ...props,
+      },
+      data() {
+        return {
+          shiftTimeUnitWidth: 0,
+          ...data,
+        };
+      },
+      mocks: {
+        $apollo: {
+          queries: {
+            shiftTimeUnitWidth: 0,
+          },
+        },
+      },
+    });
+  }
+
+  beforeEach(() => {
+    createComponent();
+  });
+
+  afterEach(() => {
+    wrapper.destroy();
+  });
+
+  const findRotationAssignee = () => wrapper.findComponent(RotationsAssignee);
+
+  describe('shift overlaps inside the current time-frame', () => {
+    it('should render a rotation assignee child component', () => {
+      expect(findRotationAssignee().exists()).toBe(true);
+    });
+
+    it('calculates the correct rotation assignee styles when the shift starts at the beginning of the time-frame cell', () => {
+      /**
+       * Where left should be 0px i.e. beginning of time-frame cell
+       * and width should be overlapping days * CELL_WIDTH(3 * 50)
+       */
+      createComponent({ data: { shiftTimeUnitWidth: CELL_WIDTH } });
+      expect(findRotationAssignee().props('rotationAssigneeStyle')).toEqual({
+        left: '0px',
+        width: '150px',
+      });
+    });
+
+    it('calculates the correct rotation assignee styles when the shift does not start at the beginning of the time-frame cell', () => {
+      /**
+       * Where left should be 52px i.e. ((DAYS_IN_WEEK - (timeframeEndsAt - overlapStartDate)) * CELL_WIDTH) + ASSIGNEE_SPACER(((7 - (20 - 14)) * 50)) + 2
+       * and width should be overlapping days * (CELL_WIDTH + offset)(1 * (50 + 50))
+       * where offset is either CELL_WIDTH * 0 or CELL_WIDTH * 1 depending on the index of the timeframe
+       */
+      createComponent({
+        props: { shift: { ...shift, startsAt: '2021-01-14T10:04:56.333Z' } },
+        data: { shiftTimeUnitWidth: CELL_WIDTH },
+      });
+      expect(findRotationAssignee().props('rotationAssigneeStyle')).toEqual({
+        left: '52px',
+        width: '100px',
+      });
+    });
+  });
+
+  describe('shift does not overlap inside the current time-frame or contains an invalid date', () => {
+    it.each`
+      reason                                            | expectedTimeframeItem    | startsAt                      | endsAt
+      ${'timeframe is an invalid date'}                 | ${new Date(NaN)}         | ${shift.startsAt}             | ${shift.endsAt}
+      ${'shift start date is an invalid date'}          | ${timeframeItem}         | ${'Invalid date string'}      | ${shift.endsAt}
+      ${'shift end date is an invalid date'}            | ${timeframeItem}         | ${shift.startsAt}             | ${'Invalid date string'}
+      ${'shift is not inside the timeframe'}            | ${timeframeItem}         | ${'2021-03-12T10:00:00.000Z'} | ${'2021-03-16T10:00:00.000Z'}
+      ${'timeframe does not represent the shift times'} | ${new Date(2021, 3, 21)} | ${shift.startsAt}             | ${shift.endsAt}
+    `(`should not render a rotation item when $reason`, (data) => {
+      const { expectedTimeframeItem, startsAt, endsAt } = data;
+      createComponent({
+        props: {
+          timeframeItem: expectedTimeframeItem,
+          shift: { ...shift, startsAt, endsAt },
+        },
+      });
+
+      expect(findRotationAssignee().exists()).toBe(false);
+    });
+  });
+});

locale/gitlab.pot

@@ -10854,15 +10854,15 @@ msgstr ""
 msgid "End Time"
 msgstr ""
 
-msgid "Ends at %{endsAt}"
-msgstr ""
-
 msgid "Ends at (UTC)"
 msgstr ""
 
 msgid "Ends on"
 msgstr ""
 
+msgid "Ends: %{endsAt}"
+msgstr ""
+
 msgid "Enforce DNS rebinding attack protection"
 msgstr ""
 
@@ -15524,6 +15524,9 @@ msgstr ""
 msgid "Invalid login or password"
 msgstr ""
 
+msgid "Invalid period"
+msgstr ""
+
 msgid "Invalid pin code"
 msgstr ""
 
@@ -26935,15 +26938,15 @@ msgstr ""
 msgid "Starts %{startsIn}"
 msgstr ""
 
-msgid "Starts at %{startsAt}"
-msgstr ""
-
 msgid "Starts at (UTC)"
 msgstr ""
 
 msgid "Starts on"
 msgstr ""
 
+msgid "Starts: %{startsAt}"
+msgstr ""
+
 msgid "State your message to activate"
 msgstr ""
 

spec/frontend/lib/utils/datetime_utility_spec.js

@@ -842,3 +842,58 @@ describe('format24HourTimeStringFromInt', () => {
     });
   });
 });
+
+describe('getOverlappingDaysInPeriods', () => {
+  const start = new Date(2021, 0, 11);
+  const end = new Date(2021, 0, 13);
+
+  describe('when date periods overlap', () => {
+    const givenPeriodLeft = new Date(2021, 0, 11);
+    const givenPeriodRight = new Date(2021, 0, 14);
+
+    it('returns an overlap object that contains the amount of days overlapping, start date of overlap and end date of overlap', () => {
+      expect(
+        datetimeUtility.getOverlappingDaysInPeriods(
+          { start, end },
+          { start: givenPeriodLeft, end: givenPeriodRight },
+        ),
+      ).toEqual({
+        daysOverlap: 2,
+        overlapStartDate: givenPeriodLeft.getTime(),
+        overlapEndDate: end.getTime(),
+      });
+    });
+  });
+
+  describe('when date periods do not overlap', () => {
+    const givenPeriodLeft = new Date(2021, 0, 9);
+    const givenPeriodRight = new Date(2021, 0, 10);
+
+    it('returns an overlap object that contains a 0 value for days overlapping', () => {
+      expect(
+        datetimeUtility.getOverlappingDaysInPeriods(
+          { start, end },
+          { start: givenPeriodLeft, end: givenPeriodRight },
+        ),
+      ).toEqual({ daysOverlap: 0 });
+    });
+  });
+
+  describe('when date periods contain an invalid Date', () => {
+    const startInvalid = new Date(NaN);
+    const endInvalid = new Date(NaN);
+    const error = __('Invalid period');
+
+    it('throws an exception when the left period contains an invalid date', () => {
+      expect(() =>
+        datetimeUtility.getOverlappingDaysInPeriods({ start, end }, { start: startInvalid, end }),
+      ).toThrow(error);
+    });
+
+    it('throws an exception when the right period contains an invalid date', () => {
+      expect(() =>
+        datetimeUtility.getOverlappingDaysInPeriods({ start, end }, { start, end: endInvalid }),
+      ).toThrow(error);
+    });
+  });
+});