♟ TDD the Chess\Glossary\PhaseTerm class

[programarivm]

A game is divided into three different phases: Opening, middlegame, and endgame. A new term called Chess\Glossary\PhaseTerm needs to be implemented in the php-chess/src/Glossary folder to describe the phase of the game. The PHPUnit tests are to be written in the php-chess/tests/unit/Glossary/PhaseTermTest.php file accordingly.