Clarify that some words are reserved and cannot be used as Views path

Think this can actually be classified as a bug and may need some validation + test coverage. Since it results in a error message.

Thanks for fast feedback, it's really great that issues can maintain their momentum. I have changed the category to bug, and added some more tasks.

Thinking more about this, wouldn't it be great, if Drupal listed reserved paths somewhere, perhaps on the Status page? I have added a proposal in the Issue Summary, what do you think?

I have added test coverage. Leaving the test coverage loose (assertNotContains(200)) as I do not think the validation is in place yet. Once it is, might be best to tighten the test to test for the validation string?

Not sure that’s the test coverage we would need. The validation should be that these reserved words can’t be saved. So that’s what the tests should check I would assume.

@ressa to answer your question not sure status report page would be needed to get the visibility it needs. But definitely should be documented somewhere, maybe the help topic?

Re: #11 I have added a @todo. To complete the todo may require the validation to be in place to test on the exact validation error text.

Thanks @oily for adding test coverage, it's a big help.

@smustgrave: Using the Help page is a great idea, and I have added it in the Issue Summary as well as MR, and demoted the Status page suggestion. We could expand it, and link to it from the Views path field description text? Or maybe it's fine as it is ...

Remove Views Help page text from Issue Summary, since it is in the MR.

I have been searching through the views module to work out where to put the validation for the views page display form. I think it would be in DisplayPluginBase.php perhaps before line 2533. That is where the 'more link' path? is validated. So could add validation for the page display path above or below it? The more link validation seems to have useful error code can be utilised.