“Hello World” - The TDD way?

Question

Well I have been thinking about this for a while, ever since I was introduced to TDD. Which would be the best way to build a \"Hello World\" application ? which would print \"H

Answer 1

Pseudo-code:

• Create a mock of something that accepts a stream.
• Invoke helloworld onto this mock through some sort of dependency injection (Like a constructor argument).
• Verify that the "Hello World" string was streamed into your mock.

In production code, you use the prompt instead of the mock.

Rule of thumb:

• Define your success criteria in how the component interacts with other stuff, not just how it interacts with you. TDD focuses on external behavior.
• Set up the environment (mocks) to handle the chain of events.
• Run it.
• Verify.