fix: stub globally registered components

When specifying the components to stub, merge the globally registered components into the locally registered ones. (fix #1272)

packages/create-instance/create-instance.js

@@ -52,8 +52,14 @@ export default function createInstance(
   // root instance when it's instantiated
   const instanceOptions = extractInstanceOptions(options)
 
+  const globalComponents = _Vue.options.components || {}
+  const componentsToStub = Object.assign(
+    Object.create(globalComponents),
+    componentOptions.components
+  )
+
   const stubComponentsObject = createStubsFromStubsObject(
-    componentOptions.components,
+    componentsToStub,
     // $FlowIgnore
     options.stubs,
     _Vue

test/specs/mounting-options/stubs.spec.js

@@ -568,4 +568,26 @@ describeWithShallowAndMount('options.stub', mountingMethod => {
     expect(wrapper.find(ToStub).exists()).to.be.false
     expect(wrapper.find(Stub).exists()).to.be.true
   })
+
+  it('stubs globally registered components', () => {
+    const ChildComponent = {
+      template: '<div />',
+      props: ['propA'],
+      name: 'child-component'
+    }
+    const TestComponent = {
+      template: '<child-component prop-a="A" />'
+    }
+
+    Vue.component('child-component', ChildComponent)
+    const wrapper = mountingMethod(TestComponent, {
+      stubs: {
+        ChildComponent: true
+      }
+    })
+    const result = wrapper.find(ChildComponent)
+    expect(result.exists()).to.be.true
+    expect(result.props().propA).to.equal('A')
+    delete Vue.options.components['child-component']
+  })
 })