No, they are doing something wrong. They're trying to do TDD as part of a waterfall process, just with the order of the testing and development steps reversed.
The real point of TDD (IMHO) is that writing the tests forces you to use the functions, and therefore shows you the places where the functions are hard to use. You're supposed to pay attention to pain. When a test is hard to write, it's telling you that the functions are hard to use. Listen to that. Change the functions so that they're easier to use. That feedback loop is what TDD is all about.
Also, when I did TDD, we wrote the test, wrote the non-functional skeleton of the function, ran the test, watched it fail, then implemented the function, ran the test, and watched it pass. That is, a function and the tests for it were written at the same time - tests first, but the function was written within, say, five minutes or less. Writing all the tests first? Um, no. Keep the feedback loop tight.
The real point of TDD (IMHO) is that writing the tests forces you to use the functions, and therefore shows you the places where the functions are hard to use. You're supposed to pay attention to pain. When a test is hard to write, it's telling you that the functions are hard to use. Listen to that. Change the functions so that they're easier to use. That feedback loop is what TDD is all about.
Also, when I did TDD, we wrote the test, wrote the non-functional skeleton of the function, ran the test, watched it fail, then implemented the function, ran the test, and watched it pass. That is, a function and the tests for it were written at the same time - tests first, but the function was written within, say, five minutes or less. Writing all the tests first? Um, no. Keep the feedback loop tight.