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by Jay Fields.
Original Post: Ruby: expectations gem
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In February I wrote about removing test noise. 10 months later, I finally took the time to write the unit testing framework I've been wanting for the past year: expectations
expectations is a lightweight unit testing framework. Tests (expectations) can be written as follows
expect 2 do 1 + 1 end
expect NoMethodError do Object.invalid_method_call end.
expectations is designed to encourage unit testing best practices such as
discourage setting more than one expectation at a time
promote maintainability by not providing a setup or teardown method
provide one syntax for setting up state based or behavior based expectation
focus on readability by providing no mechanism for describing an expectation other than the code in the expectation. Since there is no description, hopefully the programmer will be encouraged to write the most readable code possible.
A few things probably come to mind right away: sometimes setup is good, sometimes a description is a good thing, sometimes creating an object is so painful that I need to be able to add multiple assertions. All of those things are true, but generally I don't run into those situations while unit testing. Those situations generally pop up with functional testing, and while functional testing you are better off using RSpec or Test::Unit.
The more I write tests the more I believe that there doesn't need to be a silver bullet testing framework. I think expectations is a good solution for unit testing, and I think RSpec or Test::Unit are good solutions for functional testing, and I plan to use both expectations and RSpec on all my projects moving forward.
I'm currently testing several of my projects using expectations, so I do believe it's in decent shape for using, but it is still very new. As always, patches are welcome.
Here's a few more examples of how easy it is to test with expectations
Expectationsdo
# State based expectation where a value equals another value expect 2do 1+1 end
# State based expectation where an exception is expected. Simply expect the Class of the intended exception expect NoMethodErrordo Object.no_method end
# Behavior based test using a traditional mock expect mock.to_receive(:dial).with("2125551212").times(2)do |phone| phone.dial("2125551212") phone.dial("2125551212") end
# Behavior based test on a concrete mock expect Object.to_receive(:deal).with(1)do Object.deal(1) end
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