Throw exceptions when cell methods are missing.

Use reflection to capture missing cell methods and raise proper errors
on them.

Refs #3664

src/View/CellTrait.php

@@ -80,9 +80,17 @@ public function cell($cell, $data = [], $options = []) {
 			$data = array_values($data);
 		}
 
-		call_user_func_array([$cellInstance, $action], $data);
-
-		return $cellInstance;
+		try {
+			$reflect = new \ReflectionMethod($cellInstance, $action);
+			$reflect->invokeArgs($cellInstance, $data);
+			return $cellInstance;
+		} catch (\ReflectionException $e) {
+			throw new \BadMethodCallException(sprintf(
+				'Class %s does not have a "%s" method.',
+				$className,
+				$action
+			));
+		}
 	}
 
 }

tests/TestCase/View/CellTest.php

@@ -147,4 +147,15 @@ public function testUnexistingCell() {
 		$cell = $this->View->cell('Void::echoThis', ['arg1' => 'v1', 'arg2' => 'v2']);
 	}
 
+/**
+ * Tests missing method errors
+ *
+ * @expectedException \BadMethodCallException
+ * @expectedExceptionMessage Class TestApp\View\Cell\ArticlesCell does not have a "nope" method.
+ * @return void
+ */
+	public function testCellMissingMethod() {
+		$this->View->cell('Articles::nope');
+	}
+
 }