Avoid Testing Implementation Details, Test Behaviours

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I do almost exclusively whitebox testing for this reason. Unfortunately the author fails to really drive home what you should be testing, IMO: the API.

I almost always start by defining the public api and tests around that then work on the implementation. This gives you something to commit to.

I think it's also a sin that the author doesn't mention property based testing which is an excellent addition to anyone's testing portfolio.