Raise an exception when reconfiguring objects that already exist.

Instead of silently discarding the reconfiugration method call, an
exception should be raised so the developer knows that they have
probably made a mistake somewhere.

This behavior is applied to helpers/components/behaviors but not other
registry types as those are less frequently reconfigured.

Refs #4693

src/Controller/Controller.php

@@ -30,6 +30,7 @@
 use Cake\Utility\MergeVariablesTrait;
 use Cake\View\ViewVarsTrait;
 use LogicException;
+use RuntimeException;
 
 /**
  * Application controller class for organization of business logic.
@@ -347,7 +348,17 @@ public function addComponent($name, array $config = []) {
  */
 	public function loadComponent($name, array $config = []) {
 		list(, $prop) = pluginSplit($name);
-		$this->{$prop} = $this->components()->load($name, $config);
+		$components = $this->components();
+
+		if (isset($components->$name) && $config && $components->$name->config() !== $config) {
+			$msg = sprintf(
+				'The "%s" component has already been loaded with the following config: %s',
+				$name,
+				var_export($components->{$name}->config(), true)
+			);
+			throw new RuntimeException($msg);
+		}
+		$this->{$prop} = $components->load($name, $config);
 		return $this->{$prop};
 	}
 

src/ORM/Table.php

@@ -34,6 +34,7 @@
 use Cake\ORM\Marshaller;
 use Cake\Utility\Inflector;
 use Cake\Validation\Validator;
+use RuntimeException;
 
 /**
  * Represents a single database table.
@@ -498,10 +499,20 @@ public function entityClass($name = null) {
  * @param string $name The name of the behavior. Can be a short class reference.
  * @param array $options The options for the behavior to use.
  * @return void
+ * @throws \RuntimeException If a behavior is being reloaded.
  * @see \Cake\ORM\Behavior
  */
 	public function addBehavior($name, array $options = []) {
-		$this->_behaviors->load($name, $options);
+		$behaviors = $this->_behaviors;
+		if (isset($behaviors->$name) && $behaviors->{$name}->config() !== $options) {
+			$msg = sprintf(
+				'The "%s" behavior has already been loaded with the following config: %s',
+				$name,
+				var_export($behaviors->{$name}->config(), true)
+			);
+			throw new RuntimeException($msg);
+		}
+		$behaviors->load($name, $options);
 	}
 
 /**

src/View/View.php

@@ -29,6 +29,7 @@
 use Cake\View\ViewVarsTrait;
 use InvalidArgumentException;
 use LogicException;
+use RuntimeException;
 
 /**
  * View, the V in the MVC triad. View interacts with Helpers and view variables passed
@@ -771,14 +772,23 @@ public function addHelper($helperName, array $config = []) {
 /**
  * Loads a helper. Delegates to the `HelperRegistry::load()` to load the helper
  *
- * @param string $helperName Name of the helper to load.
+ * @param string $name Name of the helper to load.
  * @param array $config Settings for the helper
  * @return Helper a constructed helper object.
  * @see HelperRegistry::load()
  */
-	public function loadHelper($helperName, array $config = []) {
-		list(, $class) = pluginSplit($helperName);
-		return $this->{$class} = $this->helpers()->load($helperName, $config);
+	public function loadHelper($name, array $config = []) {
+		list(, $class) = pluginSplit($name);
+		$helpers = $this->helpers();
+		if ($helpers->loaded($class) && $config && $helpers->$class->config() !== $config) {
+			$msg = sprintf(
+				'The "%s" helper has already been loaded with the following config: %s',
+				$name,
+				var_export($helpers->{$class}->config(), true)
+			);
+			throw new RuntimeException($msg);
+		}
+		return $this->{$class} = $helpers->load($name, $config);
 	}
 
 /**

tests/TestCase/Controller/ControllerTest.php

@@ -812,7 +812,7 @@ public function testComponents() {
  *
  * @return void
  */
-	public function testAddComponent() {
+	public function testLoadComponent() {
 		$request = new Request('/');
 		$response = $this->getMock('Cake\Network\Response');
 
@@ -825,4 +825,25 @@ public function testAddComponent() {
 		$this->assertTrue(isset($registry->Paginator));
 	}
 
+/**
+ * Test adding a component that is a duplicate.
+ *
+ * @return void
+ */
+	public function testLoadComponentDuplicate() {
+		$request = new Request('/');
+		$response = $this->getMock('Cake\Network\Response');
+
+		$controller = new TestController($request, $response);
+		$this->assertNotEmpty($controller->loadComponent('Paginator'));
+		$this->assertNotEmpty($controller->loadComponent('Paginator'));
+		try {
+			$controller->loadComponent('Paginator', ['bad' => 'settings']);
+			$this->fail('No exception');
+		} catch (\RuntimeException $e) {
+			$this->assertContains('The "Paginator" component has already been loaded', $e->getMessage());
+		}
+	}
+
+
 }

tests/TestCase/ORM/TableTest.php

@@ -1069,6 +1069,23 @@ public function testAddBehavior() {
 		$table->addBehavior('Sluggable');
 	}
 
+/**
+ * Test adding a behavior that is a duplicate.
+ *
+ * @return void
+ */
+	public function testAddBehaviorDuplicate() {
+		$table = new Table(['table' => 'articles']);
+		$this->assertNull($table->addBehavior('Sluggable', ['test' => 'value']));
+		$this->assertNull($table->addBehavior('Sluggable', ['test' => 'value']));
+		try {
+			$table->addBehavior('Sluggable');
+			$this->fail('No exception raised');
+		} catch (\RuntimeException $e) {
+			$this->assertContains('The "Sluggable" behavior has already been loaded', $e->getMessage());
+		}
+	}
+
 /**
  * Test removing a behavior from a table.
  *

tests/TestCase/View/ViewTest.php

@@ -920,6 +920,23 @@ public function testLoadHelper() {
 		$this->assertEquals('bar', $config['foo']);
 	}
 
+/**
+ * Test loading helper when duplicate.
+ *
+ * @return void
+ */
+	public function testLoadHelperDuplicate() {
+		$View = new View();
+
+		$this->assertNotEmpty($View->loadHelper('Html', ['foo' => 'bar']));
+		try {
+			$View->loadHelper('Html', ['test' => 'value']);
+			$this->fail('No exception');
+		} catch (\RuntimeException $e) {
+			$this->assertContains('The "Html" helper has already been loaded', $e->getMessage());
+		}
+	}
+
 /**
  * Test loadHelpers method
  *