public function testSetRightTreeObject()
 {
     $obj_binaryTree = new BinaryTree('content');
     $obj_binaryTree->setRightTree(null);
     $this->assertFalse($obj_binaryTree->isEmpty(), 'Binary tree should not be empty.');
     $this->assertEquals('content', $obj_binaryTree->getObject(), 'Binary tree\'s object should equal content.');
     $this->assertNotNull($obj_binaryTree->getLeftTree(), 'Left tree should not be null.');
     $this->assertTrue($obj_binaryTree->getLeftTree()->isEmpty(), 'Left tree should be empty.');
     $this->assertNotNull($obj_binaryTree->getRightTree(), 'Right tree should not be null.');
     $this->assertTrue($obj_binaryTree->getRightTree()->isEmpty(), 'Right tree should be empty.');
     $obj_binaryTree->setRightTree(new BinaryTree('content R'));
     $this->assertFalse($obj_binaryTree->isEmpty(), 'Binary tree should not be empty.');
     $this->assertEquals('content', $obj_binaryTree->getObject(), 'Binary tree\'s object should equal content.');
     $this->assertNotNull($obj_binaryTree->getLeftTree(), 'Left tree should not be null.');
     $this->assertTrue($obj_binaryTree->getLeftTree()->isEmpty(), 'Left tree should be empty.');
     $this->assertNotNull($obj_binaryTree->getRightTree(), 'Right tree should not be null.');
     $this->assertFalse($obj_binaryTree->getRightTree()->isEmpty(), 'Right tree should not be empty.');
     $this->assertEquals('content R', $obj_binaryTree->getRightTree()->getObject(), 'Right tree\'s object should equal content R.');
     $obj_binaryTreeEmpty = new BinaryTree();
     $obj_binaryTreeEmpty->setRightTree(new BinaryTree('content R'));
     $this->assertTrue($obj_binaryTreeEmpty->isEmpty(), 'Binary tree is empty.');
     $this->assertNull($obj_binaryTreeEmpty->getObject(), 'Content should be null.');
     $this->assertNull($obj_binaryTreeEmpty->getLeftTree(), 'Left tree should be null.');
     $this->assertNull($obj_binaryTreeEmpty->getRightTree(), 'Right tree should be null.');
 }