Build/Test Tools: Document PHP unit test classes.

Props boonebgorges.
Fixes #35494.


git-svn-id: https://develop.svn.wordpress.org/trunk@36854 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/includes/factory/class-wp-unittest-factory-for-thing.php

@@ -1,5 +1,8 @@
 <?php
 
+/**
+ * An abstract class that serves as a basis for all WordPress object-type factory classes.
+ */
 abstract class WP_UnitTest_Factory_For_Thing {
 
 	var $default_generation_definitions;

tests/phpunit/includes/factory/class-wp-unittest-factory.php

@@ -1,5 +1,10 @@
 <?php
 
+/**
+ * A factory for making WordPress data with a cross-object type API.
+ *
+ * Tests should use this factory to generate test fixtures.
+ */
 class WP_UnitTest_Factory {
 
 	/**