What makes a meaningful test? This question should always be asked. No matter we write your tests first or tests after, they may stay in a project for years and it is pretty important them to test the things that really matters. Badly written tests can slow us down by constantly failing on each implementation change, and such tests can be written no matter you follow TDD or not. The idea of a test is to ensure that software works and not to freeze it at specific point.
This is a companion discussion topic for the original entry at http://codeception.com/12-21-2016/writing-better-tests-expectation-vs-implementation.html