more compatible test for older vim version.

autoload/airline/section.vim

@@ -19,7 +19,6 @@ function! s:get_val(key, append)
     return a:key
   endif
 
-
   if a:append > 0
     let val .= '%{airline#util#append('.func.')}'
   elseif a:append < 0

t/util.vim

@@ -26,8 +26,9 @@ describe 'util'
   end
 
   it 'has getwinvar function'
-    Expect airline#util#getwinvar(1, '&statusline', 'foo') == getwinvar(1, '&statusline')
     Expect airline#util#getwinvar(1, 'asdf', '123') == '123'
+    call setwinvar(1, 'vspec', 'is cool')
+    Expect airline#util#getwinvar(1, 'vspec', '') == 'is cool'
   end
 
   it 'has exec funcrefs helper functions'