Problem:    Insufficient testing for reading/writing files.
Solution:   Add more tests. (Yegappan Lakshmanan, closes vim/vim#6257)
            Add "ui_delay" to test_override() and use it for the CTRL-O test.
https://github.com/vim/vim/commit/b340baed9f7fc1c19a0742e2214d54982190c15e

Omit test_override().
Reorder test_writefile.vim to match Vim.

Problem:    Some code not covered by tests.
Solution:   Add test cases. (Yegappan Lakshmanan, closes vim/vim#5649)
https://github.com/vim/vim/commit/bc2b71d44a0b90b6aeb3534a76912fccbe5577df

vim-patch:8.2.0212: missing search/substitute pattern hardly tested

Problem:    Missing search/substitute pattern hardly tested.
Solution:   Add test_clear_search_pat() and tests. (Yegappan Lakshmanan,
            closes vim/vim#5579)
https://github.com/vim/vim/commit/07ada5ff2fd8f22ed3233ae5c4ddf87c7b3f56fe

vim-patch:8.2.0250: test_clear_search_pat() is unused

Problem:    test_clear_search_pat() is unused.
Solution:   Remove the function. (Yegappan Lakshmanan, closes vim/vim#5624)
https://github.com/vim/vim/commit/4f5776c17cd86f904a7e2f92db297c73e28939b7

Problem:    Write file test still fails on MS-Windows.
Solution:   Set fileformat with the :edit command
https://github.com/vim/vim/commit/16204962c7ad7380a40f0855443303ad16114e2b

Problem:    Write file test fails on MS-Windows.
Solution:   Force edit after setting 'fileformat'.
https://github.com/vim/vim/commit/bd318559cf8dea210e943100536011473f25bf68

Problem:    First write after setting 'eol' does not have NL added. (Tomáš
            Janoušek)
Solution:   Only use b_no_eol_lnum when doing a binary write. (closes vim/vim#7535)
https://github.com/vim/vim/commit/b3c8b1d25414f2e24ad03551cdf125b3e2c142b1

Problem:    Test 42 is still old style.
Solution:   Turn it into a new style test. (Yegappan Lakshmanan, closes vim/vim#6561)
https://github.com/vim/vim/commit/b61ef01cce2afd70fbfa2805336a26643109dfb7

Including the Xtest2 -> Xfile2 change from Vim patch 8.2.1498.

Problem:    Some Ex commands not sufficiently tested.
Solution:   Add more tests. (Yegappan Lakshmanan, closes vim/vim#5565)
https://github.com/vim/vim/commit/ea3db914c0fa35797ad73f6d5bb3a4288d690065

Problem:    Not easy to recognize the system Vim runs on.
Solution:   Add more items to the features list. (Ozaki Kiichi, closes vim/vim#3855)
https://github.com/vim/vim/commit/39536dd557e847e80572044c2be319db5886abe3

Some doc changes have already been applied. Some others are N/A.
"moon" was removed in patch 8.2.0427 so I did not add it.

Problem:    Some code is not tested.
Solution:   Add some more tests. (Dominique Pellé, closes vim/vim#8735)
https://github.com/vim/vim/commit/bd9e7961256ea6a98bd5a7bfe14e32c4c47186e6

Include Test_confirm_write_partial_file() anyway, even though it will
not be run.