vim-patch:8.2.4343: when reloading not all properties are detected

Problem:    When reloading not all properties are detected.
Solution:   Add the "edit" value to v:fcs_choice. (Rob Pilling, closes vim/vim#9579)
https://github.com/vim/vim/commit/8196e94a8b72ed8618605cb66615571313097d78

Cherry-pick some test changes from patch 8.1.1826.

2 files changed, 105 insertions, 7 deletions

diff --git a/src/nvim/testdir/setup.vim b/src/nvim/testdir/setup.vim
index fdae0697c3..15e3b31498 100644
--- a/src/nvim/testdir/setup.vim
+++ b/src/nvim/testdir/setup.vim
@@ -10,6 +10,7 @@ let s:did_load = 1
 set backspace=
 set directory^=.
 set fillchars=vert:\|,fold:-
+set fsync
 set laststatus=1
 set listchars=eol:$
 set joinspaces
diff --git a/src/nvim/testdir/test_filechanged.vim b/src/nvim/testdir/test_filechanged.vim
index b4c32fcc16..06ccd6e85f 100644
--- a/src/nvim/testdir/test_filechanged.vim
+++ b/src/nvim/testdir/test_filechanged.vim
@@ -1,9 +1,10 @@
 " Tests for when a file was changed outside of Vim.
 
+source check.vim
+
 func Test_FileChangedShell_reload()
-  if !has('unix')
-    return
-  endif
+  CheckUnix
+
   augroup testreload
     au FileChangedShell Xchanged_r let g:reason = v:fcs_reason | let v:fcs_choice = 'reload'
   augroup END
@@ -90,11 +91,107 @@ func Test_FileChangedShell_reload()
   call delete('Xchanged_r')
 endfunc
 
+func Test_FileChangedShell_edit()
+  CheckUnix
+
+  new Xchanged_r
+  call setline(1, 'reload this')
+  set fileformat=unix
+  write
+
+  " File format changed, reload (content only, no 'ff' etc)
+  augroup testreload
+    au!
+    au FileChangedShell Xchanged_r let g:reason = v:fcs_reason | let v:fcs_choice = 'reload'
+  augroup END
+  call assert_equal(&fileformat, 'unix')
+  sleep 10m  " make the test less flaky in Nvim
+  call writefile(["line1\r", "line2\r"], 'Xchanged_r')
+  let g:reason = ''
+  checktime
+  call assert_equal('changed', g:reason)
+  call assert_equal(&fileformat, 'unix')
+  call assert_equal("line1\r", getline(1))
+  call assert_equal("line2\r", getline(2))
+  %s/\r
+  write
+
+  " File format changed, reload with 'ff', etc
+  augroup testreload
+    au!
+    au FileChangedShell Xchanged_r let g:reason = v:fcs_reason | let v:fcs_choice = 'edit'
+  augroup END
+  call assert_equal(&fileformat, 'unix')
+  sleep 10m  " make the test less flaky in Nvim
+  call writefile(["line1\r", "line2\r"], 'Xchanged_r')
+  let g:reason = ''
+  checktime
+  call assert_equal('changed', g:reason)
+  call assert_equal(&fileformat, 'dos')
+  call assert_equal('line1', getline(1))
+  call assert_equal('line2', getline(2))
+  set fileformat=unix
+  write
+
+  au! testreload
+  bwipe!
+  call delete(undofile('Xchanged_r'))
+  call delete('Xchanged_r')
+endfunc
+
+func Test_FileChangedShell_edit_dialog()
+  throw 'Skipped: requires a UI to be active'
+  CheckNotGui
+
+  new Xchanged_r
+  call setline(1, 'reload this')
+  set fileformat=unix
+  write
+
+  " File format changed, reload (content only) via prompt
+  augroup testreload
+    au!
+    au FileChangedShell Xchanged_r let g:reason = v:fcs_reason | let v:fcs_choice = 'ask'
+  augroup END
+  call assert_equal(&fileformat, 'unix')
+  call writefile(["line1\r", "line2\r"], 'Xchanged_r')
+  let g:reason = ''
+  call feedkeys('L', 'L') " load file content only
+  checktime
+  call assert_equal('changed', g:reason)
+  call assert_equal(&fileformat, 'unix')
+  call assert_equal("line1\r", getline(1))
+  call assert_equal("line2\r", getline(2))
+  %s/\r
+  write
+
+  " File format changed, reload (file and options) via prompt
+  augroup testreload
+    au!
+    au FileChangedShell Xchanged_r let g:reason = v:fcs_reason | let v:fcs_choice = 'ask'
+  augroup END
+  call assert_equal(&fileformat, 'unix')
+  call writefile(["line1\r", "line2\r"], 'Xchanged_r')
+  let g:reason = ''
+  call feedkeys('a', 'L') " load file content and options
+  checktime
+  call assert_equal('changed', g:reason)
+  call assert_equal(&fileformat, 'dos')
+  call assert_equal("line1", getline(1))
+  call assert_equal("line2", getline(2))
+  set fileformat=unix
+  write
+
+  au! testreload
+  bwipe!
+  call delete(undofile('Xchanged_r'))
+  call delete('Xchanged_r')
+endfunc
+
 func Test_file_changed_dialog()
-  throw 'Skipped: requires a UI to a active'
-  if !has('unix') || has('gui_running')
-    return
-  endif
+  throw 'Skipped: requires a UI to be active'
+  CheckUnix
+  CheckNotGui
   au! FileChangedShell
 
   new Xchanged_d