patch 8.1.1476: no statistics displayed after running tests

Problem:    No statistics displayed after running tests.
Solution:   Summarize the test results. (Christian Brabandt, closes #4391)
            Also make it possible to report a skipped file.

src/testdir/summarize.vim

@@ -0,0 +1,60 @@
+if 1
+  " This is executed with the eval feature
+  set nocp
+  func Count(match, type)
+    if a:type ==# 'executed'
+      let g:executed += (a:match+0)
+    elseif a:type ==# 'failed'
+      let g:failed = a:match+0
+    elseif a:type ==# 'skipped'
+      let g:skipped += 1
+      call extend(g:skipped_output, ["\t".a:match])
+    endif
+  endfunc
+
+  let g:executed = 0
+  let g:skipped = 0
+  let g:failed = 0
+  let g:skipped_output = []
+  let g:failed_output = []
+  let output = [""]
+
+  try
+    " This uses the :s command to just fetch and process the output of the
+    " tests, it doesn't acutally replay anything
+    %s/^Executed\s\+\zs\d\+\ze\s\+tests/\=Count(submatch(0),'executed')/egn
+    %s/^SKIPPED \zs.*/\=Count(submatch(0), 'skipped')/egn
+    %s/^\(\d\+\)\s\+FAILED:/\=Count(submatch(1), 'failed')/egn
+
+    call extend(output, ["Skipped:"]) 
+    call extend(output, skipped_output)
+
+    call extend(output, [
+          \ "",
+          \ "-------------------------------",
+          \ printf("Executed: %5d Tests", g:executed),
+          \ printf(" Skipped: %5d Tests", g:skipped),
+          \ printf("  %s: %5d Tests", g:failed == 0 ? 'Failed' : 'FAILED', g:failed),
+          \ "",
+          \ ]) 
+    if filereadable('test.log')
+      " outputs and indents the failed test result
+      call extend(output, ["", "Failures: "])
+      let failed_output = filter(readfile('test.log'), { v,k -> !empty(k)})
+      call extend(output, map(failed_output, { v,k -> "\t".k}))
+      " Add a final newline
+      call extend(output, [""])
+    endif
+
+  catch  " Catch-all
+  finally
+    call writefile(output, 'test_result.log')  " overwrites an existing file
+    q!
+  endtry
+endif
+
+" This is executed without the eval feature
+%d
+r test.log
+w test_result.log
+q!