fix: setProps() throws an error if the property is the same reference (…

…#791)

packages/test-utils/src/wrapper.js

@@ -659,6 +659,19 @@ export default class Wrapper implements BaseWrapper {
  `is not defined on the component`
  )
  }
+ if (
+ typeof data[key] === 'object' &&
+ data[key] !== null &&
+ // $FlowIgnore : Problem with possibly null this.vm
+ data[key] === this.vm[key]
+ ) {
+ throwError(
+ `wrapper.setProps() called with the same object ` +
+ `of the existing ${key} property. ` +
+ `You must call wrapper.setProps() with a new object ` +
+ `to trigger reactivity`
+ )
+ }
 
  if (this.vm && this.vm._props) {
  this.vm._props[key] = data[key]

test/specs/wrapper/setProps.spec.js

@@ -169,6 +169,36 @@ describeWithShallowAndMount('setProps', mountingMethod => {
  expect(wrapper.vm.data).to.equal('1,2,3,4,5')
  })
 
+ it('should same reference when called with same object', () => {
+ const TestComponent = {
+ template: `<div></div>`,
+ props: ['obj']
+ }
+ const wrapper = mountingMethod(TestComponent)
+ const obj = {}
+ wrapper.setProps({ obj })
+ expect(wrapper.props().obj).to.equal(obj)
+ })
+
+ it('throws an error if property is same reference', () => {
+ const TestComponent = {
+ template: `<div></div>`,
+ props: ['obj']
+ }
+ const obj = {}
+ const wrapper = mountingMethod(TestComponent, {
+ propsData: {
+ obj
+ }
+ })
+
+ const message = '[vue-test-utils]: wrapper.setProps() called with the same object of the existing obj property. You must call wrapper.setProps() with a new object to trigger reactivity'
+ const fn = () => wrapper.setProps({ obj })
+ expect(fn)
+ .to.throw()
+ .with.property('message', message)
+ })
+
  it('throws an error if node is not a Vue instance', () => {
  const message = 'wrapper.setProps() can only be called on a Vue instance'
  const compiled = compileToFunctions('<div><p></p></div>')