[kilotaras]

Code coverage in itself isn't a very useful metric. Classic example is big test with no asserts will get you pretty good coverage.

There's a rather computationally intensive technique called mutation testing where you introduce bugs into code (e.g. change + to -, flip conditionals, etc.) and check that tests fail.

[burntsushi]

Code coverage has been useful to me in practice, so I think blanket statements like "code coverage isn't useful" is very misleading. For example, code coverage has helped me identify specific branches in my code that are untested, which in turn help guide me to write additional unit tests.

You don't need to completely dismiss other testing techniques. Mutation testing can be useful at the same time that code coverage is useful.

[yazaddaruvala]

Totally agreed. Branch coverage has been far more useful to me than line coverage has.