Rename test file to match func, class, or method.

Per the WordPress Core coding standards, test files should
be named according to the function, class, or method under
test within its test class.

Function under test:
wpFunctioName.php

Class under test:
wpClassName.php

Method under test:
wpClassName/methodName.php

See https://make.wordpress.org/core/handbook/testing/automated-testing/writing-phpunit-tests/#naming-and-organization.