How to test class methods in RSPEC

Question

I wrote a simple class method Buy.get_days(string), and is trying to test it with different text string inputs. However I feel it is very verbose.

• Is there any more concise way to test the following?
• Is there a equivalent of subject for methods which I can just keep passing different parameters in and check the results?
• Is there a way to avoid the unnecessary description at each it?

thanks

 describe Buy do
   describe '.get_days' do
    it 'should get days' do
      Buy.get_days('Includes a 1-weeknight stay for up to 4 people')
      .should == 1
      end
    it 'should get days' do
      Buy.get_days('Includes a 1-night stay in a King Studio Room with stone fireplace')
      .should == 1
    end
    it 'should get days' do
      Buy.get_days('Includes 4 nights/5 days at the Finisterra Hotel for up to two adults and two children (staying in the same room)')
      .should == 4
    end
  end
end

Answer 1

Apparently there is a described_class method.

https://www.relishapp.com/rspec/rspec-core/docs/metadata/described-class

I suppose it's cleaner than subject.class, since it doesn't introduce another . method call, which reduces readability.

Using either described_class or subject.class may be more DRY than mentioning the class explicitly in every example. But personally I think not getting the syntax highlighting that comes with mentioning the class name explicitly is kind of a bummer, and I think it reduces readability, despite it totally winning in the maintainability department.

A question arises regarding best practice:

Should you use described_class whenever possible inside and outside the .expect() method, or only within the expect() method?

Answer 2

There isn't a subject equivalent for calling a method, so using it is the way to go here. The issue I see with your code as presented is that it doesn't actually explain what you are testing for. I would write something more like:

describe Buy do
  describe '.get_days' do
    it 'should detect hyphenated weeknights' do
      Buy.get_days('Includes a 1-weeknight stay for up to 4 people').should == 1
    end
    it 'should detect hyphenated nights' do
      Buy.get_days('Includes a 1-night stay in a King Studio Room with stone fireplace').should == 1
    end
    it 'should detect first number' do
      Buy.get_days('Includes 4 nights/5 days at the Finisterra Hotel for up to two adults and two children (staying in the same room)').should == 4
    end
  end
end

I'm making assumptions about what you're after here, but hopefully the idea is clear. This will also lead to much more helpful error output when a test fails. Hope this helps!

Answer 3

This might be an old question but you can always use subject.class to get by:

describe Buy do
  describe '.get_days' do
    it { expect(subject.class.get_days('Includes a 1-weeknight stay for up to 4 people')).to eq 1 }
  end
end

Answer 4

This is an interesting though perhaps more obtuse way to use the 'subject' block with Class methods.

Edit: The broken link as reported by the Wayback Archive which I suppose is susceptible to the same problem.