Remove line breaks from meta tag output

This should be added to MetaNameBase::output().

Some test coverage would be useful, to make sure this works as expected.

I created a method to allow subclasses implement a custom filter when it is necessary. Please review.

That's a good start, but can you please move the logic back into the parent MetaNameBase meta tag? There's no point in having to do this on a per-tag basis.

Hi Damien! I did a new commit moving the logic to parent class, please let me know if now the solution is ok.

I did that to avoid affect any other class which extends MetaNameBase.

The only issue I can see with this is that meta tags with URLs to file names which include multiple concurrent spaces would have problems, but honestly that's something sites should resolve using something like Transliterate Filenames.

Beyond that, this looks good.

Now for some test coverage.

@Anybody: No, that wouldn't fix the underlying problem and would just make it more complicated to manage.

Hi Damien!

I made a unit test for the new function filterValue, please let me know if it's ok.

Other than some minor whitespace / coding standards corrections, this looks great!

Idea - let's combine all the logic into the existing tidy() method.

Hi Damien! Coding standard fixed, please check.

Changing to needs review

That's better, thank you.

The logic needs to be moved into the tidy() method.

Hi Damien! I moved all the logic to tidy function and fixed the tests, thank you for the support

Excellent! I love it!

I'll work on the comments a little prior to committing it, but otherwise this is perfect.

Committed, with some comment improvements. Thank you!

In addition to line breaks, meta tag output is now also cleared on duplicate spaces. This is a BC break for projects that implemented a custom filter for empty elements in the output, eg:

/**
 * Implements hook_metatags_attachments_alter().
 */
function hook_metatags_attachments_alter(array &$metatag_attachments) {
  foreach ($metatag_attachments['#attached']['html_head'] as $id => &$attachment) {
    if ($attachment[1] === 'title') {
      $attachment[0]['#attributes']['content'] = str_replace('-  -', '-', $attachment[0]['#attributes']['content']);
    }
  }
}

Well the point of this issue was to remove newlines from the output, so why are we stripping double whitespace characters here?

$value = preg_replace('/\s+/', ' ', $value);

From just reading this issue, this seems out of scope and potentially not needed at all. Or are double whitespace characters violating some metatag markup standards?

It's common practice to replace line breaks with a space, to make sure that sentences have a gap between them. It's also common to find extra spaces after the last period in a paragraph. Put these together and multiple concurrent spaces can be a side effect of joining paragraphs together. So then we strip out multiple spaces so that there's only one space separating sentences. This is a common practice and actually brings it in line with Metatag on D7.

I'm sorry this resulted in a subtle break in backwards compatibility for your sites. Looking at the custom code provided in #24 it should be simple to adjust to the new logic. FWIW we won't be reverting this change, and making it optional is over-engineering the problem and unnecessary, but I thank you for raising the point.