Use of Array.prototype.includes breaks unit tests in browsers that do not support this.

[honeroku]

Version

1.0.0-beta.16

Reproduction link

https://codesandbox.io/s/7ykvrxrw0

Steps to reproduce

1. Download codesandbox codes.
2. Run tests on IE11 with karma.

What is expected?

Tests should pass or fail, but not be terminated.

What is actually happening?

Test is terminated due to "TypeError: Object doesn't support property or method 'includes"

---

Same as #499 which reports use of 'Array.prototype.find'.

The specific line is:
https://github.com/vuejs/vue-test-utils/blob/v1.0.0-beta.16/packages/test-utils/src/wrapper.js#L519

Array.prototype.includes supported browsers:
https://caniuse.com/#search=Array.prototype.includes

[eddyerburgh]

Thanks for the issue.

Would you like to make a PR replacing includes with an alternative?

[honeroku]

@eddyerburgh Sure I will.

I found findIndex too that is not supported in IE..

[eddyerburgh]

We can't run tests against ie11 on CircleCI.

One solution would be to use eslint-compat to check for methods that aren't supported in ie11.

[38elements]

I think it resolve this issue to use babel instead of buble.
It uses Runtime transform.
It sets the targets is ie == 11.

[eddyerburgh]

The decision to use buble was because it generates more readable output.

We could revisit and compare the output to seen if babel output is readable enough.

[eddyerburgh]

This issue is fixed and will be in the next release.

I think we should keep buble for now, although we can reinvestigate when we move the repo to typescript.