Verify that every test file which references a harness file using the
"includes" directive also contains at least one reference to a value
defined in the harness file.
To support this check, extend each harness file with a list of values
which it defines.
The millisecond representation of a given Date instance is dependent on
the local system's time zone settings. In order to pass consistently
across contexts, tests for this value must take the system configuration
into account.
Introduce a test harness utility function to encapsulate these concerns.
Re-use this function across all test files that assert the exact
millisecond representation of Date instances.