Tell us about your environment

• ESLint Version: 6.1.0
• Node Version: 12.7.0
• npm Version: 6.10.2

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

Please show your full configuration:

{
    "comma-dangle": ["error", "always"]
}

What did you do? Please include the actual source code causing the issue, as well as the command that you used to run ESLint.

foo(a)

What did you expect to happen?
I expected it to warn about the missing trailing comma after a. This is true no matter which string option I'm using. I saw that comma-dangle changed in 6.0.0 so I'm guessing it has something to do with that.

What actually happened? Please include the actual, raw output from ESLint.
No errors were reported.

Are you willing to submit a pull request to fix this bug?
Yes