In unit tests: RangeError: Invalid string length

[silvanaweb]

While using react testing library that uses this library, I have encountered a difficult-to-find error when running unit tests that were just breaking and showing the following message:

node_modules/nwsapi/src/nwsapi.js:893
      source = ‘n=e;while((e=e.parentElement)){’ + source + ‘}e=n;’;

After hours of investigation, I have found out that one of the React styled components I was using had a tiny mistake in its styles. Something like:

  tbody th {
    vertical-align: middle;

    > span {
      display: inline-block;
      padding: 0;
    }
  }ç

Where a character was out of the parenthesis.

[omeralper]

I spent a day to find this out also.

[Twonky-Chris]

I had the same problem.

[richard-ling]

I just got the same thing today, too. My jest test bombs out with the same error on the same line. In my case, compileSelector is called with expression = '.makeStyles-root _:-ms-fullscreen'. The parser gets stuck in an endless cycle with selector = ' _:-ms-fullscreen' (note the leading space):

• at the top of the while loop, symbol is a space, so matches the 'Descendant combinator' case
• match is set to [' _:-ms-fullscreen', '_:-ms-fullscreen'], source is set to a string that embeds itself
• at the bottom of the while loop, selector is set to match.pop() i.e. '_:-ms-fullscreen' (no leading space).
• on next iteration of the while loop, symbol is set to _
• this does not match any case, so emits 'invalid selector' message
• at the bottom of the while loop, selector is set to match.pop() i.e. ' _:-ms-fullscreen' (with leading space)
• this is the value of selector at the start of the cycle, so the cycle repeats. On each cycle the source string grows, eventually exhausting memory.

NOTE: the recommendation for using '_:-ms-fullscreen' comes from here: https://stackoverflow.com/questions/45973976/apply-only-to-ie-11-within-media-query-for-screen-size The full string is created by Material-UI V4 CSS compiler . I'm not sure if it is valid CSS, as _ is not a valid tagname, but in any case nwsapi should not crash.

Seems that this error will occur whenever there is a space followed by an invalid selector.

[richard-ling]

Turns out issue #46 is the exact problem I described above

[dperini]

@silvanaweb / @richard-ling Your issues should have been solved by this commit: https://github.com/dperini/nwsapi/commit/12f9f59c2dc53f8c86cd8f19fe64116ca2adc638 it is part of the 2.2.3 release.

Closing this issue.