TDD and BDD Differences

I honestly don’t see the difference between BDD and TDD.

That’s because there isn’t any.

I mean, both are just tests if what is expected happens.

That’s wrong. BDD and TDD have absolutely nothing whatsoever to do with testing. None. Nada. Zilch. Zip. Nix. Not in the slightest.

Unfortunately, TDD has the word “test” in pretty much everything (not only in its name, but also in test framework, unit test, TestCase (the class you tpyically inherit from), FooTest (the class which typically holds your tests), testBar (the typical naming pattern for a test method), plus a lot test-related terminology such as “assertion” and “verification”) which leads some people to believe that it actually does have something to do with tests. So, some smart people said: “Hey, let’s just change the name” to remove any potential for confusion.

And that’s what BDD is. It’s just TDD with any test-related terminology replaced by examples-of-behavior-related terminology:

  • Test → Example
  • Assertion → Expectation
  • assertshould
  • Unit → Behavior
  • Verification → Specification
  • … and so on

BDD is just TDD with different words. If you do TDD right, you are doing BDD. The difference is that – provided you believe at least in the weak form of the Sapir-Whorf Hypothesis – the different words make it easier to do it right.

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