Test config option rule: null -> hardcoded default, false -> disabled

Author: pabzm

tests/Framework/ConfigTest.php

@@ -48,6 +48,16 @@ public function test_get_and_set()
 
         $this->assertSame(4190, $object->get('test_int'));
 
+        // If the configured value is `null`, expect the fallback value (which is `null` by default).
+        $object->set('test', null);
+        $this->assertNull($object->get('test'));
+        $this->assertSame('fallback', $object->get('test', 'fallback'));
+
+        // If the configured value is `false`, expect `false`, regardless of the fallback value.
+        $object->set('test', false);
+        $this->assertFalse($object->get('test'));
+        $this->assertFalse($object->get('test', 'wrong'));
+
         // TODO: test more code paths in get() and set()
     }