fix: throw error if target is set in options

#266

Author: eddyerburgh

docs/en/api/wrapper/trigger.md

@@ -36,3 +36,16 @@ wrapper.trigger('click', {
 
 expect(clickHandler.called).toBe(true)
 ```
+- **Setting the event target:**
+
+Under the hood, `trigger` creates an `Event` object and dispatches the event on the Wrapper element.
+
+It's not possible edit the `target` value of an `Event` object, so you can't set `target` in the options object.
+
+To add an attribute to the `target`, you need to set the value of the Wrapper element before calling `trigger`. You can do this with the `element` property.
+
+```js
+const input = wrapper.find('input')
+input.element.value = 100
+input.trigger('click')
+```

src/wrappers/wrapper.js

@@ -516,6 +516,10 @@ export default class Wrapper implements BaseWrapper {
       throwError('cannot call wrapper.trigger() on a wrapper without an element')
     }
 
+    if (options.target) {
+      throwError('you cannot set the target value of an event. See the notes section of the docs for more details—https://vue-test-utils.vuejs.org/en/api/wrapper/trigger.html')
+    }
+
     const modifiers = {
       enter: 13,
       tab: 9,

test/unit/specs/mount/Wrapper/trigger.spec.js

@@ -103,6 +103,16 @@ describe('trigger', () => {
     expect(info.calledWith(true)).to.equal(true)
   })
 
+  it('throws error if options contains a target value', () => {
+    const wrapper = mount({ render: (h) => h('div') })
+    const div = wrapper.find('div')
+    const fn = () => div.trigger('click', {
+      target: {}
+    })
+    const message = '[vue-test-utils]: you cannot set the target value of an event. See the notes section of the docs for more details—https://vue-test-utils.vuejs.org/en/api/wrapper/trigger.html'
+    expect(fn).to.throw().with.property('message', message)
+  })
+
   it('throws error if wrapper does not contain element', () => {
     const wrapper = mount({ render: (h) => h('div') })
     const div = wrapper.find('div')