fix(validators): support components returning render function from setup (fix #1596)

[LeBenLeBen]

What kind of change does this PR introduce? (check at least one)

• Bugfix. Closes Components only returning a render function from setup aren't considered components #1596
• Feature
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes
• No

The PR fulfills these requirements:

• It's submitted to the dev branch.
• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)
• All tests are passing: https://github.com/vuejs/vue-test-utils/blob/dev/.github/CONTRIBUTING.md#development-setup
• New/updated tests are included

[lmiller1990]

Any chance to add a test for this?

[LeBenLeBen]

@lmiller1990 I was expecting this 😅 I didn't add tests because I didn't find any existing tests related to this method nor validators in general in the code base. I’m not sure where these should be added, could you guide me a bit?

[lmiller1990]

Sure thing, just stick in here: https://github.com/vuejs/vue-test-utils/blob/dev/test/specs/mount.spec.js. This codebase avoids testing implementation details (good thing) and just tests things however the user would be do it (usually with mount).

There is already a test using the composition API plugin, you could copy and paste that one. Just make a component with a setup function that returns a render function and assert wrapper.html() contains whatever the render function returns.

We are in the process of moving to Jest, but until then you need to build bundle each time you change anything in packages. So add you test, and run yarn build && yarn test:unit:only to see if it passes.

[LeBenLeBen]

@lmiller1990 Thanks for the guidance, hope that fulfill your expectations, otherwise let me know!

[lmiller1990]

@LeBenLeBen if you have some time can you try merging the latest dev to your branch?

We moved to jest, it should make it easier to fix the CI and get this merged. Sorry I didn't get back to you - I thought I had pinged you, I guess not.

Can you merge in dev and push again? Everything should be green then and we can merge.

[LeBenLeBen]

@lmiller1990 Done!

[LeBenLeBen]

I’m not sure why it doesn’t work with Vue 2.5… I tried to update @vue/composition-api to the latest stable but it didn’t fix it, moving to the 1.0 beta introduce other issues and I’m not sure you want to go this way.

It seems that the oldest version supported is Vue 2.5.22. Does the compat test use the latest 2.5 patch or 2.5.0 ?

[lmiller1990]

If you are having trouble with an older failing just add a conditional to skip it, see here for an example:

vue-test-utils/test/specs/mount.spec.js

Line 98 in ba84544

vueVersion < 2.3,

Pretty keen to get this merged.

[LeBenLeBen]

@lmiller1990 🚀