List elements incorrectly merged

[Szymon Cofalik]

Followup for #12729.

Steps to reproduce:

1. Set this as editor contents:

   <ul>
   	<li><a href="#foo">foo</a>
   
   	<ol>
   		<li><em>bar</em></li>
   	</ol>
   	</li>
   </ul>
   

2. Set caret after foo (at the end of the list item).
3. Press delete key.

Result: <em> is inside <a>
Expected result: <em> should be next to <a>

You can test this bug in this manual test (test available ​git:7456617935): ​http://tests.ckeditor.dev:1030/tests/plugins/list/manual/mergelistitems

[Piotr Jasiun]

It was tested and does not work on Chrome, Firefox and IE8-11.

[Piotr Jasiun]

It should be fixed by #12729, but it looks that it fixed only Backspace case.

[Piotrek Koszuliński]

Very strange that it does not work, because we have tests for delete too. To be investigated in 4.5.1.

[Piotrek Koszuliński]

Ok, I get now why we haven't noticed this. This bug happens only when merging with a nested list. Does not happen when merging with a list item on the same level.

[Olek Nowodziński]

There's a ​http://tests.ckeditor.dev:1030/tests/plugins/list/manual/mergelistitems test, which description I find so obscure that it took me a long, long while to get what's going on there. We should focus on writing MTs that easy, they require no knowledge about the ticket whatsoever.

IMHO, this test should be split into several steps that reflect the problem, like

1. Set caret here.
2. Press X.
3. See if Y is Z.

1. Set caret there.
2. Press A.
3. See if B is C.

...

and then, eventually, at the very end, having ensured testers know what is expected of them, there could be an invitation to play a little bit like

Test merging lists items (and blocks around) with backspace/delete in both editors.

+ general principles.

KISS!

[Olek Nowodziński]

Changes in ​branch:t/13409, but without comment:8 (will be a separate ticket).

[Piotrek Koszuliński]

I rebased and pushed one additional commit to ​branch:t/13409. The code looks good, but some of the new tests fail on IE8 and IE11.

[Olek Nowodziński]

Pushed updates to ​branch:t/13409.

[Piotrek Koszuliński]

Fixed on master with ​git:03c3329.