Add tests for Entity::errors() being able to read data with a path.

Refs #3807

tests/TestCase/ORM/EntityTest.php

@@ -824,6 +824,33 @@ public function testErrorsDeep() {
 		$this->assertEquals($expected, $entity->errors('multiple'));
 	}
 
+/**
+ * Test that errors can be read with a path.
+ *
+ * @return void
+ */
+	public function testErrorPathReading() {
+		$assoc = new Entity;
+		$entity= new Entity([
+			'field' => 'value',
+			'one' => $assoc,
+			'many' => [$assoc]
+		]);
+		$entity->errors('wrong', 'Bad stuff');
+		$assoc->errors('nope', 'Terrible things');
+
+		$this->assertEquals('Bad stuff', $entity->errors('wrong'));
+		$this->assertEquals('Terrible things', $entity->errors('many.0.nope'));
+		$this->assertEquals('Terrible things', $entity->errors('one.nope'));
+		$this->assertEquals(['nope' => 'Terrible things'], $entity->errors('one'));
+		$this->assertEquals(['nope' => 'Terrible things'], $entity->errors('many.0'));
+
+		$this->assertEquals([], $entity->errors('many.0.mistake'));
+		$this->assertEquals([], $entity->errors('one.mistake'));
+		$this->assertEquals([], $entity->errors('one.1.mistake'));
+		$this->assertEquals([], $entity->errors('many.1.nope'));
+	}
+
 /**
  * Tests that changing the value of a property will remove errors
  * stored for it