This post originated from an RSS feed registered with Ruby Buzz by Ryan Davis. Original Post: ZenTest and unit_diff Feed Title: Polishing Ruby Feed URL: http://blog.zenspider.com/index.rdf Feed Description: Musings on Ruby and the Ruby Community... Latest Ruby Buzz Posts Latest Ruby Buzz Posts by Ryan Davis Latest Posts From Polishing Ruby

What do you do when you change something and your unit tests break? You look at what broke, right? But, what do you do when you look at it and you can't find out what is wrong because the text is just too big?

I just had that happen. Can you quickly tell what is broken? I can't. It looks like this:

% ruby  ./TestZenTest.rb 
Requiring ZenTest
Loaded suite ./TestZenTest
Started
.................F...............
Finished in 0.186974 seconds.

  1) Failure:
test_klasses_equals(TestZenTest) [./TestZenTest.rb:468]:
<{"Something"=>
  {"equal?"=>true,
   "attrib="=>true,
   "self.method3"=>true,
   "method1="=>true,
   "method1?"=>true,
   "method1"=>true,
   "attrib"=>true,
   "method1!"=>true}}> expected but was
<{"Something"=>
  {"equal?"=>true,
   "attrib="=>true,
   "self.[]"=>true,
   "self.method3"=>true,
   "method1="=>true,
   "method1?"=>true,
   "method1"=>true,
   "attrib"=>true,
   "method1!"=>true}}>.

33 tests, 128 assertions, 1 failures, 0 errors

So, this is just a small example. When we were working on ParseTree we'd have individual test failures that were probably 50-100 lines long, with a 1 to 2 line change somewhere in the middle. So what do you do about this??? Well, it'd be nice to just see the differences between the expected an actual result. How? You use unit_diff of course!

% ruby  ./TestZenTest.rb | unit_diff
Requiring ZenTest
Loaded suite ./TestZenTest
Started
.................F...............
Finished in 0.123412 seconds.

  1) Failure:
test_klasses_equals(TestZenTest) [./TestZenTest.rb:468]:
3a4
>    "self.[]"=>true,
33 tests, 128 assertions, 1 failures, 0 errors

This one tool knocked HOURS off our debugging time. Try it now by downloading ZenTest.

If you'd like to see ZenTest in action, check out Pat Eyler's excellent articles How to Use ZenTest with Ruby and Test-First Ruby Programming.