In today's lab we will be creating a Converter that takes in a base 10 integer and returns a Roman Numeral string:

To get started, let's watch a ~10 minute demonstration of Test Driven Development (TDD): Roman Numeral Kata.

What's surprising about the speakers approach to writing code and passing tests? (Pay special attention to the way he cheats!)

Test Driven Development can be thought of as a 3 step processs described as "Red, Green, Refactor":

1. Write the test first. Make sure the expectation is failing. ("red")
   • Why? Because if the test passes right away we have a "false positive".
2. Write code to pass the test ("green")
   • It's common to break existing features when you add a new feature. Make sure that all of your tests are passing!
3. Stop and cleanup ("refactor")
   • Is your code DRY? Are your tests DRY? As you make changes, run your tests frequently to ensure your code still works.

When pair programming one strategy is to play "ping pong". One person writes the test, the other person writes code to pass it. Then you switch roles.

Before you can start writing tests, you need to setup the RSpec test suite in your project. Please follow the official setup instructions.

At a minimum, you will need to install and configure the following gems: rspec, rspec-core, rspec-expectations. (That means you should have a Gemfile!).

Your tests or "specs" will live in a /specs folder. Since we are testing our Converter class which lives in converter.rb, we will name our spec "/specs/converter_spec.rb".

Make sure you are in the root of your project when you run the rspec command!

You will need to familiarize yourself with the "built-in matchers" included in the rspec-expectations library:

• http://www.rubydoc.info/gems/rspec-expectations/frames#Equivalence
• http://www.rubydoc.info/gems/rspec-expectations/frames#Comparisons

Want anther challenge? Try creating a "numbers to words" converter. It should accept an integer and convert it into english words:

• http://rspec.info/
• https://relishapp.com/rspec/docs/gettingstarted