patch 8.1.1677: tests get stuck when running into an existing swapfile

Problem:    Tests get stuck when running into an existing swapfile.
Solution:   Set v:swapchoice to "q" and report an error. (Daniel Hahler,
            closes #4644)

Author: brammool

src/testdir/runtest.vim

@@ -68,10 +68,14 @@ set encoding=utf-8
 let s:test_script_fname = expand('%')
 au! SwapExists * call HandleSwapExists()
 func HandleSwapExists()
-  " Only ignore finding a swap file for the test script (the user might be
+  " Ignore finding a swap file for the test script (the user might be
   " editing it and do ":make test_name") and the output file.
+  " Report finding another swap file and chose 'q' to avoid getting stuck.
   if expand('<afile>') == 'messages' || expand('<afile>') =~ s:test_script_fname
     let v:swapchoice = 'e'
+  else
+    call assert_report('Unexpected swap file: ' .. v:swapname)
+    let v:swapchoice = 'q'
   endif
 endfunc
 

src/version.c

@@ -777,6 +777,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1677,
 /**/
     1676,
 /**/