eol-last and no-trailing-spaces --fix interfere with each other

[feross]

Tell us about your environment

• ESLint Version: 3.12.2
• Node Version: 7.3.0
• npm Version: 3.10.10

What parser (default, Babel-ESLint, etc.) are you using? default

Please show your full configuration:

{
    "eol-last": 2,
    "no-trailing-spaces": 2
}

What did you do? Please include the actual source code causing the issue.
What did you expect to happen?
What actually happened? Please include the actual, raw output from ESLint.

If there are spaces on the last line, --fix will remove the spaces, but still add a newline.

In the following example I added characters to visualize newlines and spaces. An empty line is marked with a _ (underscore) and a space is marked with a . (dot).

Correct:

console.log('test')

becomes

console.log('test')
_

Wrong:

console.log('test')\n
..

becomes

console.log('test')
_
_

(Originally reported here: standard/standard#733)

[platinumazure]

What do you get for this case?

console.log('test')..\n

[johannes-z]

console.log('test')..\n

becomes

console.log('test') // all whitespaces were removed.

[feross]

Yes, all whitespaces are removed, and the \n remains. So it becomes:

console.log('test')\n

[alberto]

If you don't want multiple empty lines at the end of file, you should use no-multiple-empty-lines with {maxEOF: 1}

[feross]

@alberto We're already doing "no-multiple-empty-lines": [2, { "max": 1 }] which also sets the maxEOF and maxBOF options to 1.

This appears to be a bug in the auto-fixing code.

[feross]

Indeed, changing the setting to:

"no-multiple-empty-lines": [2, { "max": 1, "maxEOF": 1, "maxBOF": 1 }]

does not solve the problem. The fixer still adds an extra newline at the end.

[not-an-aardvark]

Correction: no-multiple-empty-lines does not count the trailing line ending in a file as a new line, so the correct config is maxEOF: 0.

[feross]

@not-an-aardvark Ah, I think you're right.

[feross]

Closing, as I don't think there's an ESLint bug here anymore.

Cheers, @not-an-aardvark!