puppet-lint --fix incorrectly removes commas, creating syntax error

[alisonatwork]

We recently encountered a bug when applying puppet-lint fixes in a CI pipeline that did not have a subsequent syntax check. The issue is that in some cases, puppet-lint --fix will "fix" the code in such a way that it is broken.

Test case:

file{'/abc':
  ensure=>directory,owner=>test,group=>test,
  mode=>'0755',
}

When running puppet-lint against this file, it complains about the indentation of => being wrong. But if you run puppet-lint --fix, it will produce a file that looks like this:

file{'/abc':
  ensure =>directory
  owner  =>test
  group  =>test,
  mode   =>'0755',
}

Note the missing commas. I guess what is happening is some kind of off-by-one error where the commas are replaced by newline+indent, because this doesn't happen if the source file had spaces after the commas.

Something that might be nice (although I am not sure how easy it would be to do) is if puppet-lint could also run a syntax check on the files it supposedly fixed as a sanity check.