WPHookHelper::get_hook_name_param(): add basic tests

[rodrigoprimo]

Description

In preparation for supporting PHPCS 4.0, this PR adds unit tests for the WPHookHelper::get_hook_name_param() method.

Suggested changelog entry

N/A

Related issues/external references

Related to: #2272

[jrfnl]

@rodrigoprimo Thanks for creating this PR. I've left some small suggestions inline, but, and more importantly, a principle question about how the tests for this method are set up.

[rodrigoprimo]

Thanks for the review, Juliette!

Instead of emulating the return value from PassedParameters::getParameters(), why not test the method with a case file and then let the test code call PassedParameters::getParameters() before calling WPHookHelper::get_hook_name_param() ?

I reworked the tests in a new commit to address your feedback:

• The tests now parse a case file and call PassedParameters::getParameters() in the test code before passing the result to WPHookHelper::get_hook_name_param(), instead of emulating that output.
• I opted to assert only on the raw content of the selected parameter, since verifying which parameter is selected is the method's main purpose, and it keeps the tests less brittle.

I also addressed the other comments you left. The unrealistic "hook name param missing" case was replaced with a named-parameter call that omits the hook name parameter, and the docblock types were updated to reflect the new structure after refactoring the tests.