A specification must, according to the Jakarta EE Specification Process (JESP), provide a test suite to verify that an implementation implements the specification correctly. This test suite is called a Test Compatibility Kit (TCK). There must be at least one compatible implementation, i.e. an implementation that passes the TCK, for a spec to be ratified as a final specification.
I will use Jakarta MVC as an example for a specification going through the steps involved in the JESP and blog about it here. Follow the Jakarta MVC tag to get them all.