Establish PSR2-compliant naming convention for test methods

[cbj4074]

Currently, we're using a mix of underscores and camelCase, with the underscores intended to differentiate between "unit under test", "condition of test", and "expected result".

This causes PHP linter failures because such names fail PSR2 compliance.

Let's establish a convention that satisfies the linter, makes sense, and embraces names of manageable length.