feat(test-utils): add 'overview' function

close vuejs#1461

docs/api/wrapper/overview.md

@@ -0,0 +1,43 @@
+## overview
+
+Prints a simple overview of the `Wrapper`.
+
+- **Example:**
+
+```js
+import { mount } from '@vue/test-utils'
+import Component from './Component.vue'
+
+const wrapper = mount(Component)
+wrapper.overview()
+
+// Console output
+/*
+Wrapper (Visible):
+
+Html:
+    <div class="test">
+      <p>My name is Tess Ting</p>
+    </div>
+
+Data: {
+    firstName: Tess,
+    lastName: Ting
+}
+
+Computed: {
+    fullName: Tess Ting'
+}
+
+Emitted: {',
+    foo: [',
+        0: [ hello, world ],
+        1: [ bye, world ]'
+    ],
+    bar: [
+        0: [ hey ]'
+    ]
+}
+
+*/
+```

flow/wrapper.flow.js

@@ -26,6 +26,7 @@ declare interface BaseWrapper {
   isVisible(): boolean | void;
   isVueInstance(): boolean | void;
   name(): string | void;
+  overview(): void;
   props(key?: string): { [name: string]: any } | any | void;
   text(): string | void;
   selector: Selector | void;

packages/test-utils/src/wrapper-array.js

@@ -143,6 +143,15 @@ export default class WrapperArray implements BaseWrapper {
     )
   }
 
+  overview(): void {
+    this.throwErrorIfWrappersIsEmpty('overview()')
+
+    throwError(
+      `overview() must be called on a single wrapper, use at(i) ` +
+        `to access a wrapper`
+    )
+  }
+
   props(): void {
     this.throwErrorIfWrappersIsEmpty('props')
 

packages/test-utils/src/wrapper.js

@@ -324,6 +324,53 @@ export default class Wrapper implements BaseWrapper {
     return this.vnode.tag
   }
 
+  /**
+   * Prints a simple overview of the wrapper current state
+   * with useful information for debugging
+   */
+  overview(): void {
+    if (!this.isVueInstance()) {
+      throwError(`wrapper.overview() can only be called on a Vue instance`)
+    }
+    const identation = 4
+    const formatJSON = (json: string, replacer: Function = null) =>
+      JSON.stringify(json, replacer, identation).replace(/"/g, '')
+
+    const visibility = this.isVisible() ? 'Visible' : 'Not visible'
+
+    const html = this.html()
+      ? this.html().replace(/^(?!\s*$)/gm, ' '.repeat(identation)) + '\n'
+      : ''
+
+    const data = formatJSON(this.vm.$data)
+
+    const computed = this.vm._computedWatchers
+      ? formatJSON(
+          ...Object.keys(this.vm._computedWatchers).map(computedKey => ({
+            [computedKey]: this.vm[computedKey]
+          }))
+        )
+      : '{}'
+
+    const emittedJSONReplacer = (key, value) =>
+      value instanceof Array
+        ? value.map(
+            (calledWith, index) => `${index}: [ ${calledWith.join(', ')} ]`
+          )
+        : value
+
+    const emitted = formatJSON(this.emitted(), emittedJSONReplacer)
+
+    console.log(
+      '\n' +
+        `Wrapper (${visibility}):\n\n` +
+        `Html:\n${html}\n` +
+        `Data: ${data}\n\n` +
+        `Computed: ${computed}\n\n` +
+        `Emitted: ${emitted}\n`
+    )
+  }
+
   /**
    * Returns an Object containing the prop name/value pairs on the element
    */

test/specs/wrapper-array/overview.spec.js

@@ -0,0 +1,24 @@
+import { describeWithShallowAndMount } from '~resources/utils'
+import { compileToFunctions } from 'vue-template-compiler'
+import '@vue/test-utils'
+
+describeWithShallowAndMount('overview', mountingMethod => {
+  it('throws error if wrapper array contains no items', () => {
+    const wrapper = mountingMethod(compileToFunctions('<div />'))
+    const message = '[vue-test-utils]: overview() cannot be called on 0 items'
+
+    expect(() => wrapper.findAll('p').overview())
+      .to.throw()
+      .with.property('message', message)
+  })
+
+  it('throws error when called on a WrapperArray', () => {
+    const wrapper = mountingMethod(compileToFunctions('<div><div /></div>'))
+    const message =
+      '[vue-test-utils]: overview() must be called on a single wrapper, use at(i) to access a wrapper'
+
+    expect(() => wrapper.findAll('div').overview())
+      .to.throw()
+      .with.property('message', message)
+  })
+})