vim-patch:8.0.1222: test functions interfere with each other

Problem:    Test functions interfere with each other.
Solution:   Cleanup tab pages, windows and buffers.  Reset option.

ce11de87e2

src/nvim/testdir/runtest.vim

@@ -110,7 +110,11 @@ func RunTheTest(test)
     endtry
   endif
 
-  " Close any extra windows and make the current one not modified.
+  " Close any extra tab pages and windows and make the current one not modified.
+  while tabpagenr('$') > 1
+    bwipe!
+  endwhile
+
   while 1
     let wincount = winnr('$')
     if wincount == 1
@@ -123,7 +127,15 @@ func RunTheTest(test)
       break
     endif
   endwhile
+
+  " Wipe out all buffers except the current one, then wipe the current one.
+  for nr in range(1, bufnr('$'))
+    if nr != bufnr('%') && bufexists(nr)
+      exe nr . 'bwipe!'
+    endif
+  endfor
   set nomodified
+  bwipe
 endfunc
 
 func AfterTheTest()

src/nvim/testdir/test_filetype.vim

@@ -547,7 +547,7 @@ func Test_script_detection()
     for file in files
       call writefile(file, 'Xtest')
       split Xtest
-      call assert_equal(ft, &filetype)
+      call assert_equal(ft, &filetype, 'for text: ' . string(file))
       bwipe!
     endfor
   endfor

src/nvim/testdir/test_tabpage.vim

@@ -475,6 +475,7 @@ endfunc
 
 func Test_close_on_quitpre()
   " This once caused a crash
+  edit Xtest
   new
   only
   set bufhidden=delete
@@ -489,7 +490,7 @@ func Test_close_on_quitpre()
   while tabpagenr('$') > 1
     bwipe!
   endwhile
-  1b
+  buf Xtest
 endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab