diff --git a/src/testdir/dumps/Test_diff_17.dump b/src/testdir/dumps/Test_diff_17.dump
new file mode 100644
index 0000000..101df35
--- /dev/null
+++ b/src/testdir/dumps/Test_diff_17.dump
@@ -0,0 +1,20 @@
+| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0| @33||+1&&| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0| @33
+| +0#0000e05#a8a8a8255@1| +0#0000000#5fd7ff255@34||+1&#ffffff0| +0#0000e05#a8a8a8255@1|-+0#4040ff13#afffff255@34
+| +0#0000e05#a8a8a8255@1|c+0#0000000#ffffff0|d| @32||+1&&| +0#0000e05#a8a8a8255@1|c+0#0000000#ffffff0|d| @32
+| +0#0000e05#a8a8a8255@1|e+0#0000000#ffffff0|f| @32||+1&&| +0#0000e05#a8a8a8255@1| +0#0000000#ffffff0@34
+| +0#0000e05#a8a8a8255@1|x+2#0000000#ff404010@2| +0&#ffd7ff255@31||+1&#ffffff0| +0#0000e05#a8a8a8255@1|e+0#0000000#ffffff0|f| @32
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|y+2#0000000#ff404010@2| +0&#ffd7ff255@31
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+|X+3#0000000&|f|i|l|e|1| @12|1|,|1| @11|A|l@1| |X+1&&|f|i|l|e|2| @12|1|,|1| @11|A|l@1
+|:+0&&> @73
diff --git a/src/testdir/dumps/Test_diff_18.dump b/src/testdir/dumps/Test_diff_18.dump
new file mode 100644
index 0000000..7f17531
--- /dev/null
+++ b/src/testdir/dumps/Test_diff_18.dump
@@ -0,0 +1,20 @@
+| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0| @33||+1&&| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0| @33
+| +0#0000e05#a8a8a8255@1| +0#0000000#ffffff0@34||+1&&| +0#0000e05#a8a8a8255@1|c+0#0000000#ffffff0|d| @32
+| +0#0000e05#a8a8a8255@1|c+0#0000000#ffffff0|d| @32||+1&&| +0#0000e05#a8a8a8255@1| +0#0000000#ffffff0@34
+| +0#0000e05#a8a8a8255@1|e+0#0000000#ffffff0|f| @32||+1&&| +0#0000e05#a8a8a8255@1|e+0#0000000#ffffff0|f| @32
+| +0#0000e05#a8a8a8255@1|x+2#0000000#ff404010@2| +0&#ffd7ff255@31||+1&#ffffff0| +0#0000e05#a8a8a8255@1|y+2#0000000#ff404010@2| +0&#ffd7ff255@31
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+|X+3#0000000&|f|i|l|e|1| @12|1|,|1| @11|A|l@1| |X+1&&|f|i|l|e|2| @12|1|,|1| @11|A|l@1
+|:+0&&> @73
diff --git a/src/testdir/dumps/Test_diff_19.dump b/src/testdir/dumps/Test_diff_19.dump
new file mode 100644
index 0000000..f2d0611
--- /dev/null
+++ b/src/testdir/dumps/Test_diff_19.dump
@@ -0,0 +1,20 @@
+| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0| @33||+1&&| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|x+0#0000000#ffffff0| @33||+1&&| +0#0000e05#a8a8a8255@1|x+0#0000000#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|c+0#0000000#ffd7ff255|d| @32||+1&#ffffff0| +0#0000e05#a8a8a8255@1|c+0#0000000#ffd7ff255| +2&#ff404010|d+0&#ffd7ff255| @31
+| +0#0000e05#a8a8a8255@1|e+0#0000000#ffd7ff255|f| @32||+1&#ffffff0| +0#0000e05#a8a8a8255@1| +2#0000000#ff404010|e+0&#ffd7ff255|f| @31
+| +0#0000e05#a8a8a8255@1|x+0#0000000#ffd7ff255@1| | +2&#ff404010|x+0&#ffd7ff255@1| @28||+1&#ffffff0| +0#0000e05#a8a8a8255@1|x+0#0000000#ffd7ff255@1| |x@1| @29
+| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @31||+1&&| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @31
+| +0#0000e05#a8a8a8255@1|-+0#4040ff13#afffff255@34||+1#0000000#ffffff0| +0#0000e05#a8a8a8255@1| +0#0000000#5fd7ff255@34
+| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @31||+1&&| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @31
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+|X+3#0000000&|f|i|l|e|1| @12|1|,|1| @11|A|l@1| |X+1&&|f|i|l|e|2| @12|1|,|1| @11|A|l@1
+|:+0&&> @73
diff --git a/src/testdir/dumps/Test_diff_20.dump b/src/testdir/dumps/Test_diff_20.dump
new file mode 100644
index 0000000..1dbd07c
--- /dev/null
+++ b/src/testdir/dumps/Test_diff_20.dump
@@ -0,0 +1,20 @@
+| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0| @33||+1&&| +0#0000e05#a8a8a8255@1|a+0#0000000#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|x+0#0000000#ffffff0| @33||+1&&| +0#0000e05#a8a8a8255@1|x+0#0000000#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|c+0#0000000#ffffff0|d| @32||+1&&| +0#0000e05#a8a8a8255@1|c+0#0000000#ffffff0| |d| @31
+| +0#0000e05#a8a8a8255@1|e+0#0000000#ffffff0|f| @32||+1&&| +0#0000e05#a8a8a8255@1| +0#0000000#ffffff0|e|f| @31
+| +0#0000e05#a8a8a8255@1|x+0#0000000#ffffff0@1| @1|x@1| @28||+1&&| +0#0000e05#a8a8a8255@1|x+0#0000000#ffffff0@1| |x@1| @29
+| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @31||+1&&| +0#0000e05#a8a8a8255@1|f+0#0000000#ffffff0|o@1| @31
+| +0#0000e05#a8a8a8255@1|-+0#4040ff13#afffff255@34||+1#0000000#ffffff0| +0#0000e05#a8a8a8255@1| +0#0000000#5fd7ff255@34
+| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @31||+1&&| +0#0000e05#a8a8a8255@1|b+0#0000000#ffffff0|a|r| @31
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33||+1#0000000&| +0#0000e05#a8a8a8255@1|~+0#4040ff13#ffffff0| @33
+|X+3#0000000&|f|i|l|e|1| @12|1|,|1| @11|A|l@1| |X+1&&|f|i|l|e|2| @12|1|,|1| @11|A|l@1
+|:+0&&> @73
diff --git a/src/testdir/test_diffmode.vim b/src/testdir/test_diffmode.vim
index 0022a73..5ee22e2 100644
--- a/src/testdir/test_diffmode.vim
+++ b/src/testdir/test_diffmode.vim
@@ -671,16 +671,18 @@
   bwipe!
 endfunc
 
-func WriteDiffFiles(list1, list2)
+func WriteDiffFiles(buf, list1, list2)
   call writefile(a:list1, 'Xfile1')
   call writefile(a:list2, 'Xfile2')
+  if a:buf
+    call term_sendkeys(a:buf, ":checktime\<CR>")
+  endif
 endfunc
 
-" Verify a screendump with both the external and external diff.
+" Verify a screendump with both the internal and external diff.
 func VerifyBoth(buf, dumpfile, extra)
-  call term_sendkeys(a:buf, ":diffupdate!\<cr>")
   " trailing : for leaving the cursor on the command line
-  for cmd in [":set diffopt=filler" . a:extra . "\<cr>:", ":set diffopt+=internal\<cr>:"]
+  for cmd in [":set diffopt=filler" . a:extra . "\<CR>:", ":set diffopt+=internal\<CR>:"]
     call term_sendkeys(a:buf, cmd)
     if VerifyScreenDump(a:buf, a:dumpfile, {}, cmd =~ 'internal' ? 'internal' : 'external')
       break " don't let the next iteration overwrite the "failed" file.
@@ -688,6 +690,14 @@
   endfor
 endfunc
 
+" Verify a screendump with the internal diff only.
+func VerifyInternal(buf, dumpfile, extra)
+  call term_sendkeys(a:buf, ":diffupdate!\<CR>")
+  " trailing : for leaving the cursor on the command line
+  call term_sendkeys(a:buf, ":set diffopt=internal,filler" . a:extra . "\<CR>:")
+  call VerifyScreenDump(a:buf, a:dumpfile, {})
+endfunc
+
 func Test_diff_screen()
   if !CanRunVimInTerminal() || !has('menu')
     return
@@ -697,36 +707,36 @@
   call delete('.Xfile2.swp')
 
   " Test 1: Add a line in beginning of file 2
-  call WriteDiffFiles([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
+  call WriteDiffFiles(0, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
   let buf = RunVimInTerminal('-d Xfile1 Xfile2', {})
   " Set autoread mode, ,so that Vim won't complain once we re-write the test
   " files
-  call term_sendkeys(buf, ":set autoread\<cr>\<c-w>w:set autoread\<cr>\<c-w>w")
+  call term_sendkeys(buf, ":set autoread\<CR>\<c-w>w:set autoread\<CR>\<c-w>w")
 
   call VerifyBoth(buf, 'Test_diff_01', '')
 
   " Test 2: Add a line in beginning of file 1
-  call WriteDiffFiles([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
+  call WriteDiffFiles(buf, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
   call VerifyBoth(buf, 'Test_diff_02', '')
 
   " Test 3: Add a line at the end of file 2
-  call WriteDiffFiles([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11])
+  call WriteDiffFiles(buf, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11])
   call VerifyBoth(buf, 'Test_diff_03', '')
 
   " Test 4: Add a line at the end of file 1
-  call WriteDiffFiles([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
+  call WriteDiffFiles(buf, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
   call VerifyBoth(buf, 'Test_diff_04', '')
 
   " Test 5: Add a line in the middle of file 2, remove on at the end of file 1
-  call WriteDiffFiles([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11], [1, 2, 3, 4, 4, 5, 6, 7, 8, 9, 10])
+  call WriteDiffFiles(buf, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11], [1, 2, 3, 4, 4, 5, 6, 7, 8, 9, 10])
   call VerifyBoth(buf, 'Test_diff_05', '')
 
   " Test 6: Add a line in the middle of file 1, remove on at the end of file 2
-  call WriteDiffFiles([1, 2, 3, 4, 4, 5, 6, 7, 8, 9, 10], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11])
+  call WriteDiffFiles(buf, [1, 2, 3, 4, 4, 5, 6, 7, 8, 9, 10], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11])
   call VerifyBoth(buf, 'Test_diff_06', '')
 
   " Test 7 - 9: Test normal/patience/histogram diff algorithm
-  call WriteDiffFiles(['#include <stdio.h>', '', '// Frobs foo heartily', 'int frobnitz(int foo)', '{',
+  call WriteDiffFiles(buf, ['#include <stdio.h>', '', '// Frobs foo heartily', 'int frobnitz(int foo)', '{',
       \ '    int i;', '    for(i = 0; i < 10; i++)', '    {', '        printf("Your answer is: ");',
       \ '        printf("%d\n", foo);', '    }', '}', '', 'int fact(int n)', '{', '    if(n > 1)', '    {',
       \ '        return fact(n-1) * n;', '    }', '    return 1;', '}', '', 'int main(int argc, char **argv)',
@@ -748,7 +758,7 @@
 
   " Test 10-11: normal/indent-heuristic
   call term_sendkeys(buf, ":set diffopt&vim\<cr>")
-  call WriteDiffFiles(['', '  def finalize(values)', '', '    values.each do |v|', '      v.finalize', '    end'],
+  call WriteDiffFiles(buf, ['', '  def finalize(values)', '', '    values.each do |v|', '      v.finalize', '    end'],
       \ ['', '  def finalize(values)', '', '    values.each do |v|', '      v.prepare', '    end', '',
       \ '    values.each do |v|', '      v.finalize', '    end'])
   call term_sendkeys(buf, ":diffupdate!\<cr>")
@@ -759,19 +769,19 @@
   call VerifyScreenDump(buf, 'Test_diff_11', {})
 
   " Test 12: diff the same file
-  call WriteDiffFiles([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
+  call WriteDiffFiles(buf, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
   call VerifyBoth(buf, 'Test_diff_12', '')
 
   " Test 13: diff an empty file
-  call WriteDiffFiles([], [])
+  call WriteDiffFiles(buf, [], [])
   call VerifyBoth(buf, 'Test_diff_13', '')
 
   " Test 14: test diffopt+=icase
-  call WriteDiffFiles(['a', 'b', 'cd'], ['A', 'b', 'cDe'])
+  call WriteDiffFiles(buf, ['a', 'b', 'cd'], ['A', 'b', 'cDe'])
   call VerifyBoth(buf, 'Test_diff_14', " diffopt+=filler diffopt+=icase")
 
   " Test 15-16: test diffopt+=iwhite
-  call WriteDiffFiles(['int main()', '{', '   printf("Hello, World!");', '   return 0;', '}'],
+  call WriteDiffFiles(buf, ['int main()', '{', '   printf("Hello, World!");', '   return 0;', '}'],
       \ ['int main()', '{', '   if (0)', '   {', '      printf("Hello, World!");', '      return 0;', '   }', '}'])
   call term_sendkeys(buf, ":diffupdate!\<cr>")
   call term_sendkeys(buf, ":set diffopt&vim diffopt+=filler diffopt+=iwhite\<cr>")
@@ -779,6 +789,22 @@
   call term_sendkeys(buf, ":set diffopt+=internal\<cr>")
   call VerifyScreenDump(buf, 'Test_diff_16', {})
 
+  " Test 17: test diffopt+=iblank
+  call WriteDiffFiles(buf, ['a', ' ', 'cd', 'ef', 'xxx'], ['a', 'cd', '', 'ef', 'yyy'])
+  call VerifyInternal(buf, 'Test_diff_17', " diffopt+=iblank")
+
+  " Test 18: test diffopt+=iblank,iwhite / iwhiteall / iwhiteeol
+  call VerifyInternal(buf, 'Test_diff_18', " diffopt+=iblank,iwhite")
+  call VerifyInternal(buf, 'Test_diff_18', " diffopt+=iblank,iwhiteall")
+  call VerifyInternal(buf, 'Test_diff_18', " diffopt+=iblank,iwhiteeol")
+
+  " Test 19: test diffopt+=iwhiteeol
+  call WriteDiffFiles(buf, ['a ', 'x', 'cd', 'ef', 'xx  xx', 'foo', 'bar'], ['a', 'x', 'c d', ' ef', 'xx xx', 'foo', '', 'bar'])
+  call VerifyInternal(buf, 'Test_diff_19', " diffopt+=iwhiteeol")
+
+  " Test 19: test diffopt+=iwhiteall
+  call VerifyInternal(buf, 'Test_diff_20', " diffopt+=iwhiteall")
+
   " clean up
   call StopVimInTerminal(buf)
   call delete('Xfile1')