Introduce autoDestroy config option

docs/api/config.md

@@ -89,3 +89,50 @@ import { config } from '@vue/test-utils'
 
 config.silent = false
 ```
+
+### `autoDestroy`
+
+- type: `boolean | Function`
+- default: `false`
+
+This allows you to call `wrapper.destroy()` automatically—either when creating a new wrapper or by passing a hook function.
+
+Please note that setting `autoDestroy: true` only destroys existing instances when a new instance is created which result in one wrapper instance remaining.
+Therefore passing a hook function is usually a better idea. 
+
+Examples:
+
+```js
+import { config, mount } from '@vue/test-utils'
+
+config.autoDestroy = true
+
+const Component = {
+  template: '<div>come ponente</div>'
+}
+
+const firstWrapper = mount(Component)
+expect(firstWrapper.text()).not.toBe('come levant')
+
+const secondWrapper = mount(Component) // this will call firstWrapper.destroy()
+expect(firstWrapper.text()).not.toBe('come sirocco')
+```
+
+```js
+import { config, mount } from '@vue/test-utils'
+
+config.autoDestroy = afterEach // will call wrapper.destroy() after each test case
+
+const Component = {
+  template: '<div>come ponente</div>'
+}
+
+describe('my component', () => {
+  it('is not East wind', () => {
+    const wrapper = mount(Component)
+    expect(wrapper.text()).not.toBe('levant')
+
+    // wrapper.destroy() is called after this
+  })
+})
+```

flow/config.flow.js

@@ -3,5 +3,6 @@ declare type Config = {
   mocks?: Object,
   methods?: { [name: string]: Function },
   provide?: Object,
-  silent?: boolean
+  silent?: boolean,
+  autoDestroy?: boolean | Function
 }

packages/test-utils/src/config.js

@@ -3,5 +3,6 @@ export default {
   mocks: {},
   methods: {},
   provide: {},
-  silent: true
+  silent: true,
+  autoDestroy: false
 }

packages/test-utils/src/wrapper.js

@@ -15,6 +15,13 @@ import { matches } from './matches'
 import createDOMEvent from './create-dom-event'
 import { throwIfInstancesThrew } from './error'
 
+const wrapperInstances = []
+
+const destroyAllInstances = () => {
+  wrapperInstances.forEach(wrapper => wrapper.destroy())
+  wrapperInstances.length = 0
+}
+
 export default class Wrapper implements BaseWrapper {
   +vnode: VNode | null
   +vm: Component | void
@@ -67,6 +74,17 @@ export default class Wrapper implements BaseWrapper {
     ) {
       this.isFunctionalComponent = true
     }
+
+    const { autoDestroy } = config
+    if (autoDestroy) {
+      if (autoDestroy instanceof Function) {
+        autoDestroy(destroyAllInstances)
+      } else {
+        destroyAllInstances()
+      }
+
+      wrapperInstances.push(this)
+    }
   }
 
   at(): void {

test/specs/config.spec.js

@@ -1,4 +1,5 @@
 import { describeWithShallowAndMount } from '~resources/utils'
+import Component from '~resources/components/component.vue'
 import ComponentWithProps from '~resources/components/component-with-props.vue'
 import { itDoNotRunIf } from 'conditional-specs'
 import { config, createLocalVue } from '~vue/test-utils'
@@ -109,4 +110,44 @@ describeWithShallowAndMount('config', mountingMethod => {
     })
     expect(console.error).calledWith(sandbox.match('[Vue warn]'))
   })
+
+  describe('autoDestroy', () => {
+    it('does not destroy wrapper when autoDestroy is set to false', () => {
+      config.autoDestroy = false
+      const localVue = createLocalVue()
+      const wrapper = mountingMethod(Component, { localVue })
+      sandbox.spy(wrapper, 'destroy')
+
+      mountingMethod(Component, { localVue })
+
+      expect(wrapper.destroy).not.called
+    })
+
+    it('destroys wrapper when autoDestroy is set to true', () => {
+      config.autoDestroy = true
+      const localVue = createLocalVue()
+      const wrapper = mountingMethod(Component, { localVue })
+      sandbox.spy(wrapper, 'destroy')
+
+      mountingMethod(Component, { localVue })
+
+      expect(wrapper.destroy).called
+    })
+
+    it('destroys wrapper when autoDestroy hook is called', () => {
+      let destroyCallback
+      config.autoDestroy = callback => {
+        destroyCallback = callback
+      }
+      const localVue = createLocalVue()
+      const wrapper = mountingMethod(Component, { localVue })
+      sandbox.spy(wrapper, 'destroy')
+
+      mountingMethod(Component, { localVue })
+
+      expect(wrapper.destroy).not.called
+      destroyCallback()
+      expect(wrapper.destroy).called
+    })
+  })
 })