test(main.spec.js): add main.js test

tests/integration/specs/main.spec.js

@@ -0,0 +1,16 @@
+import Main from '@/main'
+import Vue from 'vue'
+
+// Solves the 'RegeneratorRuntime is not defined' issue according to
+// https://stackoverflow.com/questions/28976748/regeneratorruntime-is-not-defined
+import '@babel/polyfill'
+
+describe('Main', () => {
+  it('should run main and load app', async (done) => {
+    let main = Main
+    await new Promise(resolve => setTimeout(resolve, 2000))
+    expect(main.vueInstance).not.toBeNull()  
+    expect(main.vueInstance).toBeInstanceOf(Vue)
+    done()    
+  })
+})