1 files changed, 96 insertions, 0 deletions
diff --git a/spec/frontend/observability/skeleton_spec.js b/spec/frontend/observability/skeleton_spec.js
new file mode 100644
index 00000000000..5637c0e6d70
--- /dev/null
+++ b/spec/frontend/observability/skeleton_spec.js
@@ -0,0 +1,96 @@
+import { GlSkeletonLoader } from '@gitlab/ui';
+import { shallowMountExtended } from 'helpers/vue_test_utils_helper';
+
+import ObservabilitySkeleton from '~/observability/components/skeleton/index.vue';
+import DashboardsSkeleton from '~/observability/components/skeleton/dashboards.vue';
+import ExploreSkeleton from '~/observability/components/skeleton/explore.vue';
+import ManageSkeleton from '~/observability/components/skeleton/manage.vue';
+
+import { SKELETON_VARIANT } from '~/observability/constants';
+
+describe('ObservabilitySkeleton component', () => {
+  let wrapper;
+
+  const mountComponent = ({ ...props } = {}) => {
+    wrapper = shallowMountExtended(ObservabilitySkeleton, {
+      propsData: props,
+    });
+  };
+
+  afterEach(() => {
+    wrapper.destroy();
+    wrapper = null;
+  });
+
+  describe('on mount', () => {
+    beforeEach(() => {
+      jest.spyOn(global, 'setTimeout');
+      mountComponent();
+    });
+
+    it('should call setTimeout on mount and show ObservabilitySkeleton if Observability UI is not loaded yet', () => {
+      jest.runAllTimers();
+
+      expect(setTimeout).toHaveBeenCalledWith(expect.any(Function), 500);
+      expect(wrapper.vm.loading).toBe(true);
+      expect(wrapper.vm.timerId).not.toBeNull();
+    });
+
+    it('should call setTimeout on mount and dont show ObservabilitySkeleton if Observability UI is loaded', () => {
+      wrapper.vm.loading = false;
+      jest.runAllTimers();
+
+      expect(setTimeout).toHaveBeenCalledWith(expect.any(Function), 500);
+      expect(wrapper.vm.loading).toBe(false);
+      expect(wrapper.vm.timerId).not.toBeNull();
+    });
+  });
+
+  describe('handleSkeleton', () => {
+    it('will not show the skeleton if Observability UI is loaded before', () => {
+      jest.spyOn(global, 'clearTimeout');
+      mountComponent();
+      wrapper.vm.handleSkeleton();
+      expect(clearTimeout).toHaveBeenCalledWith(wrapper.vm.timerId);
+    });
+
+    it('will hide skeleton gracefully after 400ms if skeleton was present on screen before Observability UI', () => {
+      jest.spyOn(global, 'setTimeout');
+      mountComponent();
+      jest.runAllTimers();
+      wrapper.vm.handleSkeleton();
+      jest.runAllTimers();
+
+      expect(setTimeout).toHaveBeenCalledWith(wrapper.vm.hideSkeleton, 400);
+      expect(wrapper.vm.loading).toBe(false);
+    });
+  });
+
+  describe('skeleton variant', () => {
+    it.each`
+      skeletonType    | condition                                         | variant
+      ${'dashboards'} | ${'variant is dashboards'}                        | ${SKELETON_VARIANT.DASHBOARDS}
+      ${'explore'}    | ${'variant is explore'}                           | ${SKELETON_VARIANT.EXPLORE}
+      ${'manage'}     | ${'variant is manage'}                            | ${SKELETON_VARIANT.MANAGE}
+      ${'default'}    | ${'variant is not manage, dashboards or explore'} | ${'unknown'}
+    `('should render $skeletonType skeleton if $condition', async ({ skeletonType, variant }) => {
+      mountComponent({ variant });
+      const showsDefaultSkeleton = ![
+        SKELETON_VARIANT.DASHBOARDS,
+        SKELETON_VARIANT.EXPLORE,
+        SKELETON_VARIANT.MANAGE,
+      ].includes(variant);
+      expect(wrapper.findComponent(DashboardsSkeleton).exists()).toBe(
+        skeletonType === SKELETON_VARIANT.DASHBOARDS,
+      );
+      expect(wrapper.findComponent(ExploreSkeleton).exists()).toBe(
+        skeletonType === SKELETON_VARIANT.EXPLORE,
+      );
+      expect(wrapper.findComponent(ManageSkeleton).exists()).toBe(
+        skeletonType === SKELETON_VARIANT.MANAGE,
+      );
+
+      expect(wrapper.findComponent(GlSkeletonLoader).exists()).toBe(showsDefaultSkeleton);
+    });
+  });
+});