[BUGFIX] Support overloaded methods in StandardVariableProvider (#467)

Switches method_exists to is_callable to support overloaded
methods that extract property values.

src/Core/Variables/StandardVariableProvider.php

@@ -344,7 +344,7 @@ protected function detectAccessor($subject, $propertyName)
         if (is_object($subject)) {
             $upperCasePropertyName = ucfirst($propertyName);
             $getter = 'get' . $upperCasePropertyName;
-            if (method_exists($subject, $getter)) {
+            if (is_callable([$subject, $getter])) {
                 return self::ACCESSOR_GETTER;
             }
             if ($this->isExtractableThroughAsserter($subject, $propertyName)) {

tests/Unit/Core/Variables/StandardVariableProviderTest.php

@@ -7,6 +7,8 @@
  */
 
 use TYPO3Fluid\Fluid\Core\Variables\StandardVariableProvider;
+use TYPO3Fluid\Fluid\Tests\Unit\Core\Fixtures\ClassWithMagicGetter;
+use TYPO3Fluid\Fluid\Tests\Unit\Core\Fixtures\ClassWithProtectedGetter;
 use TYPO3Fluid\Fluid\Tests\Unit\ViewHelpers\Fixtures\UserWithoutToString;
 use TYPO3Fluid\Fluid\Tests\UnitTestCase;
 
@@ -276,4 +278,26 @@ public function getExtractRedectAccessorTestValues()
             [['test' => 'test'], 'test', StandardVariableProvider::ACCESSOR_ASSERTER, 'test'],
         ];
     }
+
+    /**
+     * @test
+     */
+    public function testExtractCallsMagicMethodGetters()
+    {
+        $provider = new StandardVariableProvider();
+        $provider->setSource(['object' => new ClassWithMagicGetter()]);
+        $result = $provider->get('object.test');
+        $this->assertEquals('test result', $result);
+    }
+
+    /**
+     * @test
+     */
+    public function testExtractReturnsNullOnProtectedGetters()
+    {
+        $provider = new StandardVariableProvider();
+        $provider->setSource(['object' => new ClassWithProtectedGetter()]);
+        $result = $provider->get('object.test');
+        $this->assertEquals(null, $result);
+    }
 }