       switch count++
 
         when 0
-          diff.should.be.within 0, 7
+          diff.should.be.approximately 0, 10
           args.should.eql ['a']
 
         when 1
-          diff.should.be.within duration, duration + 7
+          diff.should.be.approximately duration, 10
           args.should.eql ['b']
 
     fn = throttle fn, duration


    promise.then ->
      diff = Date.now() - start
      diff.should.be.within duration, duration + 7
      done()



      last = now

      if diff isnt Infinity
        diff.should.be.approximately duration, 10

      switch count++

