AutoTest with InstantRails on Windows

Testing you app is important. A useful and recommended plugin is the autotest plugin. Here's what is says in the box:

• Improves feedback by running tests continuously.
• Continually runs tests based on files you've changed.
• Get feedback as soon as you save. Keeps you in your editor allowing you to get stuff done faster.
• Focuses on running previous failures until you've fixed them.

Cool. To get it type:

>>gem install ZenTest

to run cd into your app dir and type:

>>autotest -rails

Simple, isn't it?

Well... not really.
When I did this I got a whole bunch of error messages:

.../InstantRails/ruby/lib/ruby/gems/1.8/gems/ZenTest-3.6.1/lib/autotest.rb:435:in `expand_path': couldn't find HOME environment -- expanding `~/.autotest' (ArgumentError)
from .../InstantRails/ruby/lib/ruby/gems/1.8/gems/ZenTest-3.6.1/lib/autotest.rb:435
from .../InstantRails/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
from .../InstantRails/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require'
from .../InstantRails/ruby/lib/ruby/gems/1.8/gems/ZenTest-3.6.1/bin/autotest:35
from .../InstantRails/ruby/bin/autotest:19:in `load'
from .../InstantRails/ruby/bin/autotest:19


Turns out that it's looking for an environment variable called HOME. From my tests and from what I read you can put any valid path there. I just used the local path.
Actually, I just set the variable before running autotest.

>>set HOME=.
>>autotest -rails

However, a fresh new list of errors are now generated, the gist of them is this:

.../InstantRails/ruby/lib/ruby/gems/1.8/gems/ZenTest-3.6.1/lib/unit_diff.rb:187:in ''': No such file or directory - diff.exe -u D:/temp/expect.1480.0 D:/temp/butwas.1480.0n (Errno::ENOENT)
1. from .../InstantRails/ruby/lib/ruby/gems/1.8/gems/ZenTest-3.6.1/lib/unit_diff.rb:187:in 'unit_diff'
...


Basically, it's complaining that it cannot find diff.exe. Of course, most (all?) Unix systems have this installed but my Windows machine with InstantRails does not, so therein lies the problem. This post explains it simply. Go here to get diff.exe for Windows.

Once installed (or unzipped), just set your path to wherever you put it, and run autotest. e.g.:

>>set HOME=.
>>set path=%path%;"C:\Program Files\GnuWin32\bin\"
>>autotest -rails

Right? Wrong.
diff.exe is still not found. For some reason it's not enough to set the environment like this.

You will need to set it in the Windows settings (Start-> Settings-> Control Panel-> System-> Advanced-> Environment Variables...) and change the PATH variable to include the diff.exe path.

Now you can begin enjoying the joys of autotest.

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