Operator-Linebreak Default Option Behaves Differently When Option Is Actually Specified

[epmatsw]

Tell us about your environment

• ESLint Version: 3.8.1
• Node Version: 7.0.0
• npm Version: 3.10.9

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

Please show your full configuration:

A

{
    "rules": {
        "operator-linebreak": [2, "after"]
    }
}

B

{
    "rules": {
        "operator-linebreak": [2]
    }
}

What did you do? Please include the actual source code causing the issue.

var blah = hey ?
    a : b;

What did you expect to happen?
"after" (default) requires linebreaks to be placed after the operator (except for the ternary operator characters ? and :)

Based on the docs, I would expect this code to pass with both configs.
What actually happened? Please include the actual, raw output from ESLint.
If you use config B, the line is flagged as an error. Config A passes as expected.

I think this is really a doc issue. It should be more clear that the after option and the default behavior are not interchangeable.

[not-an-aardvark]

Thanks for the report. I was going to say that this is a bug, but based on the source code it appears to be intentional. I'm not sure why, though.

If it is intentional, then I agree that the documentation should point it out.

edit: It looks like this was introduced in 4ade378

[epmatsw]

Yeah, it definitely feels buggy. And even the docs in that commit seem unclear on what the behavior should be.

[not-an-aardvark]

I figured it out: it's not that there's a bug in the rule, it's that the default configuration has overrides for ? and :. In other words, the default configuration is not just after, it's after, {overrides: {'?': before, ':': before}}.

I made a PR to update the docs at #7726.