RSpec Testing Framework

Qualified supports the RSpec behavior-driven testing framework.

These notes are adapted from rspec-core.

Basic Example

RSpec uses the words "describe" and "it" so we can express concepts like a conversation:

"Describe an order."
"It sums the prices of its line items."

describe Order do
  it "sums the prices of its line items" do
    order = Order.new

    order.add_entry(LineItem.new(:item => Item.new(
      :price => Money.new(1.11, :USD)
    )))
    order.add_entry(LineItem.new(:item => Item.new(
      :price => Money.new(2.22, :USD),
      :quantity => 2
    )))

    expect(order.total).to eq(Money.new(5.55, :USD))
  end
end

The describe method creates an ExampleGroup. Within the block passed to describe you can declare examples using the it method.

Under the hood, an example group is a class in which the block passed to describe is evaluated. The blocks passed to it are evaluated in the context of an instance of that class.

Get Started

Start with a simple example of behavior you expect from your system:

describe Calculator do
  describe '#add' do
    it 'returns the sum of its arguments' do
      expect(Calculator.new.add(1, 2)).to eq(3)
    end
  end
end

Run this by clicking the VALIDATE TEST CASES in the challenge creator, or RUN TESTS when taking a challenge, and you will see a failure similar to:

uninitialized constant Calculator (NameError)

Address the failure by defining a skeleton of the Calculator class in the Solution code area:

class Calculator
  def add(a, b)
  end
end

Now run the spec again, and watch the expectation fail:

expected: 3 got: nil (compared using ==)

Implement the simplest solution, by changing the definition of Calculator#add to:

def add(a, b)
  a + b
end

Now run the spec again, and watch it pass:

Calculator
  #add
    returns the sum of its arguments
      Test Passed

Learn More

You can learn how to use it on the RSpec Website.