patch 9.1.0135: Insufficient testing for 'delcombine'

Problem:  Insufficient testing for 'delcombine'.
Solution: Add test for both Normal and Insert modes without Arabic.
          (zeertzjq)

closes: #14086

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_options.vim b/src/testdir/test_options.vim
index 37dc201..908f0da 100644
--- a/src/testdir/test_options.vim
+++ b/src/testdir/test_options.vim
@@ -2234,4 +2234,34 @@
   set wrap& smoothscroll& scrolloff&
 endfunc
 
+func Test_delcombine()
+  new
+  set backspace=indent,eol,start
+
+  set delcombine
+  call setline(1, 'β̳̈:β̳̈')
+  normal! 0x
+  call assert_equal('β̈:β̳̈', getline(1))
+  exe "normal! A\<BS>"
+  call assert_equal('β̈:β̈', getline(1))
+  normal! 0x
+  call assert_equal('β:β̈', getline(1))
+  exe "normal! A\<BS>"
+  call assert_equal('β:β', getline(1))
+  normal! 0x
+  call assert_equal(':β', getline(1))
+  exe "normal! A\<BS>"
+  call assert_equal(':', getline(1))
+
+  set nodelcombine
+  call setline(1, 'β̳̈:β̳̈')
+  normal! 0x
+  call assert_equal(':β̳̈', getline(1))
+  exe "normal! A\<BS>"
+  call assert_equal(':', getline(1))
+
+  set backspace& delcombine&
+  bwipe!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab