Fix PostCSS plugin ignoring .stylelintignore

[joe223]

Which issue, if any, is this issue related to?

Closes #4134.

Is there anything in the PR that needs further explanation?

Relative documentation https://github.com/joe223/stylelint/blob/master/docs/user-guide/postcss-plugin.md#ignorepath.

[hudochenkov]

This solution breaks tests. Please, change your solution.

[joe223]

@hudochenkov Unit test all passed.

[hudochenkov]

Could you, please, add tests to postcssPlugin.test.js. You could take a look at ignore.test.js for examples using CLI and adopt them to PostCSS plugin API.

[joe223]

ASAP.
I have checked the

stylelint/lib/__tests__/stylelintignore-test/stylelintignore.test.js

Line 20 in 49bed2c

describe("standalone with .stylelintignore file ignoring one file", () => {

.

This unit tests cover all standalone's ignore configuration. I guess PostCSS plugin API ignorePath configuration unit test should be almost.

[joe223]

@hudochenkov I have add one unit test for postcssPlugin ignorePath option, this option works with .stylelintignore file to ignore style files.

I was too busy recently.🙁

[hudochenkov]

Thank you!

[hudochenkov]

• Fixed: PostCSS plugin ignoring .stylelintignore (#4186).