Add UncallableParameterizedCase, a specialization of Case which always fails with a clear message about missing inputs to a paramterized test case.
Unit tests which expose bugs around parameterized tests:
a) When input parameter generation hasn't been customized, paramterized tests should fail with a more clear explanation than "parameter count mismatch".
b) When input paramter generation has been customized but that customization yields zero sets of inputs for a test method, give the same explanation instead of silently skipping it.
Fixes parameterized tests so that when parameters are unknown, the test fails with a clear message.
Simplify the parameterized tests Sample now that conventions need not explicitly handle zero-arg tests.