If I was to inherit a large codebase, how would I start refactor the application using TDD?

The application has layers of authentication(financial banking company), and frankly, not knowing where to start is a big issue.

I guess follow up is, is it worth the time and effort to start using TDD if the code is not "testable"?

  • If a question is to help with home work, you need to mention it in the question. Commented Nov 25, 2014 at 23:57

1 Answer 1


This book is exactly what you need: Working Effectively with Legacy Code by Michael Feathers.

That book goes directly to both of your questions: How to start refactoring a legacy codebase, and how to approach TDD when the code is not yet testable.

Underlying both of those questions is another that the book answers: How to get a legacy codebase under test.

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