Order attributes: use getter methods to get value

Previously we were using the generic getter, `get_meta()`, which is not
the correct approach and doesn't return values during checkout.

Fixes #46

Author: JDGrimes

src/classes/entity/order/attr.php

@@ -62,6 +62,12 @@ protected function get_attr_value_from_entity( WordPoints_Entity $entity ) {
 			return null;
 		}
 
+		$method = "get_{$this->attr_key}";
+
+		if ( method_exists( $order, $method ) ) {
+			return $order->{$method}();
+		}
+
 		return $order->get_meta( $this->attr_key );
 	}
 }

tests/phpunit/tests/classes/entities.php

@@ -61,7 +61,7 @@ public function data_provider_entities() {
 						),
 					),
 					'the_context'  => array( 'site' => 1, 'network' => 1 ),
-					'create_func'  => 'WC_Helper_Order::create_order',
+					'create_func'  => array( $this, 'create_order' ),
 					'delete_func'  => 'WC_Helper_Order::delete_order',
 					'children'     => array(
 						'cart_tax' => array(
@@ -249,6 +249,23 @@ public function data_provider_entities() {
 		return $entities;
 	}
 
+	/**
+	 * Creates an order.
+	 *
+	 * @since 1.3.1
+	 *
+	 * @return WC_Order The order.
+	 */
+	public function create_order() {
+
+		$order = WC_Helper_Order::create_order();
+		$order->update_status( 'completed' );
+		$order->set_date_paid( time() );
+		$order->save();
+
+		return $order;
+	}
+
 	/**
 	 * Gets the ID from an order.
 	 *