Problem:    Duplicate code for translating script-local function name.
Solution:   Move the code to get_scriptlocal_funcname(). (Yegappan Lakshmanan,
            closes vim/vim#9393)

https://github.com/vim/vim/commit/e7f4abd38b6e05100c699900c8f87281e363beb2

Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

Problem:    Various pieces of code not covered by tests.
Solution:   Add a few more tests. (Yegappan Lakshmanan, closes vim/vim#8255)

https://github.com/vim/vim/commit/34fcb697240c1bc9e69417ed75db3b1a83479724

Nvim does not have test_unknown().

Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

Problem:    Cannot pass a lambda name to function() or funcref(). (Yegappan
            Lakshmanan)
Solution:   Handle a lambda name differently.

https://github.com/vim/vim/commit/eba3b7f6645c8f856132b4c06a009a3b0a44e21c

Co-authored-by: Bram Moolenaar <Bram@vim.org>

Problem:    assert_fails() checks the last error message.
Solution:   Check the first error, it is more relevant.  Fix all the tests
            that rely on the old behavior.

https://github.com/vim/vim/commit/9b7bf9e98f06ece595fed7a3ff53ecce89797a53

Skip test_listener.vim, test_textprop.vim, test_viminfo.vim.
Skip test_python2.vim: affected line fails and hasn't been ported.
Skip test_python3.vim: affected lines fail and haven't been ported.
Skip CHECK_LIST_MATERIALIZE.

Co-authored-by: Bram Moolenaar <Bram@vim.org>

Problem:    Insufficient testing for invalid function arguments.
Solution:   Add more tests. (Yegappan Lakshmanan, closes vim/vim#5988)

https://github.com/vim/vim/commit/99fa721944dda9d07c53c907c33466728df5c271

Omit test_listener.vim: changed again in patch 8.2.1183.
Omit test_textprop.vim: changed again in patch 8.2.1183.
Cherry-pick quickfix feature checks from patch 8.1.2373.
Omit Test_saveas() change: duplicate and removed in patch 8.2.0866.

Problem:    Regexp and other code not tested.
Solution:   Add more tests. (Yegappan Lakshmanan, closes vim/vim#5904)

https://github.com/vim/vim/commit/004a6781b3cf15ca5dd632c38cc09bb3b253d1f8

Problem:    Various functions not properly tested.
Solution:   Add more tests, especially for failures. (Yegappan Lakshmanan,
            closes vim/vim#5843)

https://github.com/vim/vim/commit/0e05de46226eb4e5ea580beefa71831f92d613d3

Cherry-pick test changes from patch 8.2.0427 and skip Test_has().
Cherry-pick Test_complete_wildmenu() change from patch 8.2.4339.

Problem:    Null dict is not handled like an empty dict.
Solution:   Fix the code and add tests. (Yegappan Lakshmanan, closes vim/vim#5968)

https://github.com/vim/vim/commit/ea04a6e8baff2f27da7cdd54bf70a5525994f76d

Nvim doesn't support modifying NULL list, so comment out a line.

Problem:    Some tests are still old style.
Solution:   Convert to new style tests. (Yegappan Lakshmanan, closes vim/vim#5957)

https://github.com/vim/vim/commit/08f4157c5cabc55bcb22f04dd7c717aba40caa34

Fix missing error message when sort() compare function fails.
Cherry-pick a line in test_utf8.vim from patch 8.2.0448.
Cherry-pick builtin_function() change from patch 8.2.0595.

Problem:    Crash when trying to divice the largest negative number by -1.
Solution:   Handle this case specifically.
https://github.com/vim/vim/commit/cdef1cefa2a440911c727558562f83ed9b00e16b