Add merge request popover with details

- Show pipeline status, title, MR Status and project path
- Popover attached to gitlab flavored markdown everywhere, including:
  + MR/Issue Title
  + MR/Issue description
  + MR/Issue comments
  + Rendered markdown files

2 files changed, 154 insertions, 0 deletions

diff --git a/spec/frontend/mr_popover/__snapshots__/mr_popover_spec.js.snap b/spec/frontend/mr_popover/__snapshots__/mr_popover_spec.js.snap
new file mode 100644
index 00000000000..5f9f13d591d
--- /dev/null
+++ b/spec/frontend/mr_popover/__snapshots__/mr_popover_spec.js.snap
@@ -0,0 +1,93 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`MR Popover loaded state matches the snapshot 1`] = `
+<glpopover-stub
+  boundary="viewport"
+  placement="top"
+  show=""
+  target=""
+>
+  <div
+    class="mr-popover"
+  >
+    <div
+      class="d-flex align-items-center justify-content-between"
+    >
+      <div
+        class="d-inline-flex align-items-center"
+      >
+        <div
+          class="issuable-status-box status-box status-box-open"
+        >
+          
+          Open
+        
+        </div>
+         
+        <span
+          class="text-secondary"
+        >
+          Opened 
+          <time>
+            just now
+          </time>
+        </span>
+      </div>
+       
+      <ciicon-stub
+        cssclasses=""
+        size="16"
+        status="[object Object]"
+      />
+    </div>
+     
+    <h5
+      class="my-2"
+    >
+      MR Title
+    </h5>
+     
+    <div
+      class="text-secondary"
+    >
+      
+      foo/bar!1
+    
+    </div>
+  </div>
+</glpopover-stub>
+`;
+
+exports[`MR Popover shows skeleton-loader while apollo is loading 1`] = `
+<glpopover-stub
+  boundary="viewport"
+  placement="top"
+  show=""
+  target=""
+>
+  <div
+    class="mr-popover"
+  >
+    <div>
+      <glskeletonloading-stub
+        class="animation-container-small mt-1"
+        lines="1"
+      />
+    </div>
+     
+    <h5
+      class="my-2"
+    >
+      MR Title
+    </h5>
+     
+    <div
+      class="text-secondary"
+    >
+      
+      foo/bar!1
+    
+    </div>
+  </div>
+</glpopover-stub>
+`;
diff --git a/spec/frontend/mr_popover/mr_popover_spec.js b/spec/frontend/mr_popover/mr_popover_spec.js
new file mode 100644
index 00000000000..79ed4163010
--- /dev/null
+++ b/spec/frontend/mr_popover/mr_popover_spec.js
@@ -0,0 +1,61 @@
+import MRPopover from '~/mr_popover/components/mr_popover';
+import { shallowMount } from '@vue/test-utils';
+
+describe('MR Popover', () => {
+  let wrapper;
+
+  beforeEach(() => {
+    wrapper = shallowMount(MRPopover, {
+      propsData: {
+        target: document.createElement('a'),
+        projectPath: 'foo/bar',
+        mergeRequestIID: '1',
+        mergeRequestTitle: 'MR Title',
+      },
+      mocks: {
+        $apollo: {
+          loading: false,
+        },
+      },
+    });
+  });
+
+  it('shows skeleton-loader while apollo is loading', () => {
+    wrapper.vm.$apollo.loading = true;
+
+    expect(wrapper.element).toMatchSnapshot();
+  });
+
+  describe('loaded state', () => {
+    it('matches the snapshot', () => {
+      wrapper.setData({
+        mergeRequest: {
+          state: 'opened',
+          createdAt: new Date(),
+          headPipeline: {
+            detailedStatus: {
+              group: 'success',
+              status: 'status_success',
+            },
+          },
+        },
+      });
+
+      expect(wrapper.element).toMatchSnapshot();
+    });
+
+    it('does not show CI Icon if there is no pipeline data', () => {
+      wrapper.setData({
+        mergeRequest: {
+          state: 'opened',
+          headPipeline: null,
+          stateHumanName: 'Open',
+          title: 'Merge Request Title',
+          createdAt: new Date(),
+        },
+      });
+
+      expect(wrapper.contains('ciicon-stub')).toBe(false);
+    });
+  });
+});