ADD: coverage for VueWrapper

[fanyer]

Summary

Add a test case of VueWrapper . The scope It covers lists below: https://github.com/akxcv/vuera/blob/master/src/wrappers/Vue.js#L85-L93
https://github.com/akxcv/vuera/blob/master/src/wrappers/Vue.js#L38-L40

[BEFORE]

[AFTER]

Anything else relevant?
For current situation of vuera , this case will fail. I'm trying to fix it in the next PR.

When to meet this case?
When using a wrapper component, the component filed is passed in curly braces of JSX, so it can be dynamicly changed in setSate operation. However this case won't occur in HOC mode or babel plugin mode.

[fanyer]

I've tried to change component dynamicly in a real demo, not in jest. It works correctly. I'll take a look at it again.

[fanyer]

Same case also occurs in https://github.com/akxcv/vuera/blob/master/tests/wrappers/VueWrapper-test.js#L122-L126 .

the original case is

it('synchronises props', () => {
    const reactAppInstance = makeReactInstanceWithVueComponent(VueComponent)
    reactAppInstance.setState({ message: 'New message!' })
    expect(document.body.innerHTML).toContain('New message!')
  })

However, I think toContain checks too loosely.
if the test is more strict, like below

 it('synchronises props', () => {
    const reactAppInstance = makeReactInstanceWithVueComponent(VueComponent)
    reactAppInstance.setState({ message: 'New message!' })
    expect(document.body.innerHTML).toBe(
      normalizeHTMLString(
      `<div id="root">
          <div>
            <input type="text" value="New message!">
            <div>
              <span>New message!</span> <button></button>
            </div>
          </div>
        </div>`
      )
    )
  })

It sync props failed actually (in jest test case, while it works correctly in real situation).

When setState({message}) , its real htmlString output should contain <span>New message!</span> , and the original case just determin whether New message! exists, which might appear in value="New message!"

I think some cases written before might lack of accuracy as well, esspeically The code left without coverage (seems only 2 warpers)

[fanyer]

This PR will raise VueWrapper coverage from 19/23 to 23/23, and the total coverage percent from 90% to 93% @akxcv

[timsayshey]

@akxcv LGTM

[akxcv]

Isn't it fixed already?