add basic test for /health

Signed-off-by: Jakub Sokołowski <jakub@status.im>

test/app.js

@@ -0,0 +1,26 @@
+import { expect } from 'chai'
+import sinon from 'sinon'
+import request from 'supertest'
+
+import App from '../src/app'
+import Builds from '../src/builds'
+import Comments from '../src/comments'
+
+let comments
+let app
+
+describe('App', () => {
+  beforeEach(() => {
+    comments = sinon.createStubInstance(Comments)
+    comments.db = sinon.createStubInstance(Builds),
+    app = App(comments)
+  })
+
+  describe('/health', () => {
+    it('should return OK', async () => {
+      let resp = await request(app.callback()).get('/health')
+      expect(resp.text).to.eq('OK')
+      expect(resp.status).to.eq(200)
+    })
+  })
+})