Adds a spec

spec/frontend/alert_management/components/alert_management_detail_spec.js

 import { mount, shallowMount } from '@vue/test-utils';
-import { GlAlert, GlLoadingIcon } from '@gitlab/ui';
+import { GlAlert, GlLoadingIcon, GlDropdownItem } from '@gitlab/ui';
 import AlertDetails from '~/alert_management/components/alert_details.vue';
+import updateAlertStatus from '~/alert_management/graphql/mutations/update_alert_status.graphql';
+import createFlash from '~/flash';
 
 import mockAlerts from '../mocks/alerts.json';
 
 const mockAlert = mockAlerts[0];
+jest.mock('~/flash');
 
 describe('AlertDetails', () => {
   let wrapper;
   const newIssuePath = 'root/alerts/-/issues/new';
+  const findStatusDropdownItem = () => wrapper.find(GlDropdownItem);
 
   function mountComponent({
     data,
@@ -31,6 +35,7 @@ describe('AlertDetails', () => {
       },
       mocks: {
         $apollo: {
+          mutate: jest.fn(),
           queries: {
             alert: {
               loading,
@@ -188,4 +193,50 @@ describe('AlertDetails', () => {
       });
     });
   });
+
+  describe('updating the alert status', () => {
+    const mockUpdatedMutationResult = {
+      data: {
+        updateAlertStatus: {
+          errors: [],
+          alert: {
+            status: 'acknowledged',
+          },
+        },
+      },
+    };
+
+    beforeEach(() => {
+      mountComponent({
+        props: { alertManagementEnabled: true, userCanEnableAlertManagement: true },
+        data: { alert: mockAlert },
+        loading: false,
+      });
+    });
+
+    it('calls `$apollo.mutate` with `updateAlertStatus` mutation and variables containing `iid`, `status`, & `projectPath`', () => {
+      jest.spyOn(wrapper.vm.$apollo, 'mutate').mockResolvedValue(mockUpdatedMutationResult);
+      findStatusDropdownItem().vm.$emit('click');
+
+      expect(wrapper.vm.$apollo.mutate).toHaveBeenCalledWith({
+        mutation: updateAlertStatus,
+        variables: {
+          iid: 'alertId',
+          status: 'TRIGGERED',
+          projectPath: 'projectPath',
+        },
+      });
+    });
+
+    it('calls `createFlash` when request fails', () => {
+      jest.spyOn(wrapper.vm.$apollo, 'mutate').mockReturnValue(Promise.reject(new Error()));
+      findStatusDropdownItem().vm.$emit('click');
+
+      setImmediate(() => {
+        expect(createFlash).toHaveBeenCalledWith(
+          'There was an error while updating the status of the alert. Please try again.',
+        );
+      });
+    });
+  });
 });