cheat sheets.

assert_difference is a nice clean assertion for your testing suite.

To use:

  assert_difference 'Model.count' do
    # some action (probably create) that will increase Model.count by 1
  end

  assert_difference 'Model.count', 23 do
    # some action that will increase Model.count by 23
  end

  assert_difference 'Model.count', -1 do
    # something to decrease Model.count, probably a destroy call
  end



  You can even assert_difference of more than 1 value ala 
    assert_difference 'Model.count, var_affected_by_same_action' do 
      #....
    end