A testing framework

Enrique has amended my task so that i cannot use any existing testing framework, not even Ruby’s built-in Test::Unit. However, i must practice test-driven development! Ha ha ha!

So here i am trying to ponder how to write a unit testing framework. Which is actually really nice because i get to decide the syntax i would like to use, and maybe – just maybe – i’ll come up with something that suits me really well and i’ll use again.

Enrique pointed me to the Given specification framework which i like because it uses the BDD ‘given/when/then’ approach for unit-level specifications. I’m already used to this kind of format for Cucumber features. Effectively, we use ‘given/then/when’ for Rspec, but it’s not made explicitly obvious. My comments in this trivial example should make it obvious:

describe "example" do
  before do
    @counter = 1             #(given)

  it "increments the counter" do
    @counter += 2            #(when)
    @counter.should == 3     #(then)

Now i think i could make the ‘given/when/then’ more obvious, and i can also simplify it. I might actually change ‘then’ to ‘expect’, meaning i can do away with the ‘should’ method. Effectively i’m saying that whatever is in the ‘expect’ block should return true, otherwise the spec fails. Here’s what i’m thinking of:

spec do
  given { @counter = 1 }
  when { @counter += 2 }
  expect { @counter == 3 }

I suppose this is what people call a DSL – a domain-specific language. That is the kind of language i’d like to use to write my specs. I’ve never written a DSL before, but i’m excited by the idea of being able to write specs like this, so i’m looking forward to giving it a go!

A little voice in the back of my head is telling me i’m going to have to finally understand ‘lambda’ properly. Lambda is one of those things that never sticks in my head. I can look it up when i need to and blunder my way to making it work, but i never really understand what it’s doing or how or why. I have a suspicion that i’ll be making extensive use of ‘lambda’ in my testing framework! :)


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