patch 8.0.1553: cannot see what digraph is used to insert a character

Problem:    Cannot see what digraph is used to insert a character.
Solution:   Show the digraph with the "ga" command. (Christian Brabandt)
diff --git a/src/testdir/test_matchadd_conceal.vim b/src/testdir/test_matchadd_conceal.vim
index d285a4c..123bdf0 100644
--- a/src/testdir/test_matchadd_conceal.vim
+++ b/src/testdir/test_matchadd_conceal.vim
@@ -7,17 +7,7 @@
   set term=ansi
 endif
 
-function! s:screenline(lnum) abort
-  let line = []
-  for c in range(1, winwidth(0))
-    call add(line, nr2char(screenchar(a:lnum, c)))
-  endfor
-  return s:trim(join(line, ''))
-endfunction
-
-function! s:trim(str) abort
-  return matchstr(a:str,'^\s*\zs.\{-}\ze\s*$')
-endfunction
+source shared.vim
 
 function! Test_simple_matchadd()
   new
@@ -30,7 +20,7 @@
   call matchadd('Conceal', '\%2l ')
   redraw!
   let lnum = 2
-  call assert_equal(expect, s:screenline(lnum))
+  call assert_equal(expect, Screenline(lnum))
   call assert_notequal(screenattr(lnum, 1), screenattr(lnum, 2))
   call assert_notequal(screenattr(lnum, 1), screenattr(lnum, 2))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 7))
@@ -53,7 +43,7 @@
   call matchadd('Conceal', '\%2l ', 10, -1, {'conceal': 'X'})
   redraw!
   let lnum = 2
-  call assert_equal(expect, s:screenline(lnum))
+  call assert_equal(expect, Screenline(lnum))
   call assert_notequal(screenattr(lnum, 1), screenattr(lnum, 2))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 7))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 10))
@@ -79,7 +69,7 @@
   call matchadd('Conceal', '\%2l ', 10, -1, {'conceal': 'X'})
   redraw!
   let lnum = 2
-  call assert_equal(expect, s:screenline(lnum))
+  call assert_equal(expect, Screenline(lnum))
   call assert_equal(screenattr(lnum, 1), screenattr(lnum, 2))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 7))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 10))
@@ -92,7 +82,7 @@
 
   call matchadd('ErrorMsg', '\%2l Test', 20, -1, {'conceal': 'X'})
   redraw!
-  call assert_equal(expect, s:screenline(lnum))
+  call assert_equal(expect, Screenline(lnum))
   call assert_equal(screenattr(lnum, 1) , screenattr(lnum, 2))
   call assert_equal(screenattr(lnum, 2) , screenattr(lnum, 7))
   call assert_notequal(screenattr(lnum, 1) , screenattr(lnum, 10))
@@ -116,7 +106,7 @@
   call matchadd('Conceal', '\%2l ', 10, -1, {})
   redraw!
   let lnum = 2
-  call assert_equal(expect, s:screenline(lnum))
+  call assert_equal(expect, Screenline(lnum))
   call assert_notequal(screenattr(lnum, 1), screenattr(lnum, 2))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 7))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 10))
@@ -129,7 +119,7 @@
   set listchars=conceal:+
   redraw!
 
-  call assert_equal(expect, s:screenline(lnum))
+  call assert_equal(expect, Screenline(lnum))
   call assert_notequal(screenattr(lnum, 1), screenattr(lnum, 2))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 7))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 10))
@@ -153,7 +143,7 @@
   syntax match MyConceal /\%2l / conceal containedin=ALL cchar=*
   redraw!
   let lnum = 2
-  call assert_equal(expect, s:screenline(lnum))
+  call assert_equal(expect, Screenline(lnum))
   call assert_notequal(screenattr(lnum, 1), screenattr(lnum, 2))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 7))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 10))
@@ -165,7 +155,7 @@
   call clearmatches()
   redraw!
 
-  call assert_equal(expect, s:screenline(lnum))
+  call assert_equal(expect, Screenline(lnum))
   call assert_notequal(screenattr(lnum, 1), screenattr(lnum, 2))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 7))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 10))
@@ -191,7 +181,7 @@
   redraw!
 
   let lnum = 2
-  call assert_equal(expect, s:screenline(lnum))
+  call assert_equal(expect, Screenline(lnum))
   call assert_equal(screenattr(lnum, 1), screenattr(lnum, 2))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 7))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 10))
@@ -204,7 +194,7 @@
   call setmatches(a)
   redraw!
 
-  call assert_equal(expect, s:screenline(lnum))
+  call assert_equal(expect, Screenline(lnum))
   call assert_notequal(screenattr(lnum, 1), screenattr(lnum, 2))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 7))
   call assert_equal(screenattr(lnum, 2), screenattr(lnum, 10))
@@ -232,7 +222,7 @@
   redraw!
 
   let lnum = 2
-  call assert_equal(expect, s:screenline(lnum))
+  call assert_equal(expect, Screenline(lnum))
   call assert_notequal(screenattr(lnum, 1) , screenattr(lnum, 2))
   call assert_notequal(screenattr(lnum, 2) , screenattr(lnum, 7))
   call assert_equal(screenattr(lnum, 1) , screenattr(lnum, 7))
@@ -254,13 +244,13 @@
   1put ='TARGET_TARGETTARGET'
   call cursor(1, 1)
   redraw
-  call assert_equal('TARGET_TARGETTARGET', s:screenline(2))
+  call assert_equal('TARGET_TARGETTARGET', Screenline(2))
 
   setlocal conceallevel=2
   call matchadd('Conceal', 'TARGET', 10, -1, {'conceal': 't'})
 
   redraw
-  call assert_equal('t_tt', s:screenline(2))
+  call assert_equal('t_tt', Screenline(2))
 
   quit!
 endfunction
@@ -276,13 +266,13 @@
   syntax on
   syntax keyword coqKwd bool conceal cchar=-
   redraw!
-  call assert_equal(expect, s:screenline(1))
+  call assert_equal(expect, Screenline(1))
   call assert_notequal(screenattr(1, 10) , screenattr(1, 11))
   call assert_notequal(screenattr(1, 11) , screenattr(1, 12))
   call assert_equal(screenattr(1, 11) , screenattr(1, 32))
   call matchadd('CheckedByCoq', '\%<2l\%>9c\%<16c')
   redraw!
-  call assert_equal(expect, s:screenline(1))
+  call assert_equal(expect, Screenline(1))
   call assert_notequal(screenattr(1, 10) , screenattr(1, 11))
   call assert_notequal(screenattr(1, 11) , screenattr(1, 12))
   call assert_equal(screenattr(1, 11) , screenattr(1, 32))