RSpec: DRY way to test a set of values

Question

I have a vote model, which has a class method called score. Basically, I created a mathematical equation in a spreadsheet, and am attempting to reproduce this in ruby. However, my first go isn't working, so I really need to start adding a ton more tests.

The way I'd like to go about testing this is to take a stack of input and output values from my spreadsheet and test them each. So basically, the tests could be construed to look like this:

 inputs = [a,b,c] ... score.should == x
 inputs = [a,b,c,d] ... score.should == y
 inputs = [c,d] .... score.should == z

However, the shortest way I've actually found to write this in RSpec is giving an example for each case, approximately like this (simplified example, but should give you the idea):

it "should have a score of X" do
  test_object = Votable.new(...)
  @user1.vote.create(:value=>##, :votable=>test_object)
  @user2.vote.create(:value=>##, :votable=>test_object)
  @user3.vote.create(:value=>##, :votable=>test_object)
  test_object.votes.score.should == X
end

So, the above works, but its a load of text for each example case, and to iron out the kinks and provide good test coverage I'd like to run about 20 or so test cases.

So, seriously, there must be a simpler way to set this up one time and then test a bunch of possible input/output combinations, right? Can anyone suggest a DRY way to do this kind of test in RSpec?

Thanks!

Answer 1

Yeah, you could do the following meta-programming to run a series of test that all follow the same format:

results = { x: ['a', 'b', 'c'], y: ['a','b','c','d'] }

results.each do |score, values|
  it "should have a score of #{score}" do
    test_object = Votable.new(...)
    values.each do |value|
      User.create(...).vote.create(value: value, votable: test_object)
    end
    test_object.votes.score.should == score
  end
end