fixup! Async.Promise: Fix test descriptions and variable names, more checks

Author: rhysd

test/Async/Promise.vimspec

@@ -131,12 +131,14 @@ Describe Async.Promise
       Assert Equals(reason, 'error')
     End
 
-    It should be pending when neither resolve() nor reject() is called
+    It should be pending forever when neither resolve() nor reject() is called
       let l = l:
       let done = 0
       let p = P.new({-> 42})
       Assert Equals(p._state, PENDING)
       let p = p.then({-> extend(l, {'done' : 1})})
+      let p = p.catch({-> extend(l, {'done' : 2})})
+      sleep 30m
       Assert Equals(p._state, PENDING)
       Assert Equals(done, 0)
     End