Why:
* Maintenance scripts in core have low test coverage
* This can cause issues such as the findDeprecated.php maintenance
script not working, as described in T374832
* Testing the broken script after fixing it will avoid the script
breaking again.
What:
* Fix the findDeprecated.php maintenance script to actually
show when code is hard-deprecated.
* Modify the script to allow mocking of the MediaWiki install
path in PHPUnit tests
* Create FindDeprecatedTest which tests that the script produces
an expected output, without being specific about how the
code finds the methods (to allow the method to be changed
as discussed in T243403)
** To do this, create a folder in the data folder for the PHPUnit
tests that has a mock file structure allowing the test to
use a fixed list of soft and hard deprecated methods.
Bug: T374832
Bug: T371167
Change-Id: Ic4933cef95ef1af7fa3939625ac1747106c71230
