The test suite is the same thing as the code, just approached from the other side.

i want the code to do this --> write the code to do this

i want the code to do this --> write the tests to specify this

the hard part is not the code or the tests. it's knowing what 'this' is supposed to be, exactly.

if you have the code, it is trivial to write the tests that will perfectly test the code. if you have the tests, it is trivial to write the code that will perfectly pass the tests.

however, none of this has anything to do with whether the code or the tests are good, and having a bad version of one will not help you write a good version of the other.