How can I detect the timing when I have to change a method in rspec?

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Suppose I have the following code.

class Answer
  enum type: %i[text checkbox image]

  def round_type
    case answer.type
    when text, checkbox
      :text
    when image
      :multimedia
    else
      raise 'Unknown type'
    end
  end  
end

require 'rails_helper'

RSpec.describe Answer, type: :model do
  describe '#round_type' do
    context 'when type is text' do
      it 'returns text' do
        # omitted 
      end
    end
    context 'when type is checkbox' do
      it 'returns text' do
      end
    end
    context 'when type is image' do
      it 'returns multimedia' do
      end
    end    
  end
end

Then I add video type to the enum. And I expect the method returns multimedia when the type is video.

But the round_type method and the test codes are not support video type. So I will finally realize it when I get an error in production.

I'd like to know what I have to change the method before the error occurs.

So, this is my question: How can I detect the timing when I have to change a method in rspec?

rspec testing ruby-on-rails unit-testing
1 Answers

If I understood you correctly, you have to make your specs a bit more dynamic and you have to test the else statement as well:

class Answer < ApplicationRecord
  enum type: %i[text checkbox image]

  def round_type
    case type
    when 'text', 'checkbox'
      :text
    when 'image'
      :multimedia
    else
      raise 'Unknown type'
    end
  end  
end

RSpec.describe Answer, type: :model do
  describe '#round_type' do
    it 'raises error for unknown type' do
      # empty `type` is an unknown type in this situation
      expect { Answer.new.round_type }.to raise_error
    end

    it 'does not raise error for available types' do
      # NOTE: loop through all types and check that `round_type` method
      #       recognizes each one.
      Answer.types.each_key do |key|
        expect { Answer.new(type: key).round_type }.to_not raise_error
      end
    end
  end
end

Next time you add a new type and forget to update round_type method, the last spec will fail.

https://relishapp.com/rspec/rspec-expectations/v/3-11/docs/built-in-matchers/raise-error-matcher

user_2070900
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