test discovery fails due to unresolvable dependencies

[PhillipPruett]

For example:

TestClass A depends on Dependency1 and has a registration for it in the test targets.
TestClass B does not depend on Dependency1 and has no registration for it in the test targets.
When resolving all test classes during test discovery where any class valid for that URL, e.g.

/tests/environment/TestClassB --> 500
/tests/environment/TestClassA --> 200
/tests/environment --> 500

originally filed by jonsequitur