Example mocking Mage helper

Mocking - Mage::helper()

Code you want to test

<?php
class MyCompany_MyModule_Model_Example_Mocking
{
    public function doSomething()
    {
        /** @var MyCompany_MyModule_Helper_Config $configHelper */
        $configHelper = Mage::helper('mycompany_mymodule/config')
        return $configHelper->getAnyConfigurationValue();
    }
}

Test implementation

<?php
class MyCompany_MyModule_Unit_Model_Example_MockingTest
    extends TechDivision_MagentoUnitTesting_TestCase_Model
{
    /**
     * @var string
     */
    protected $_testClassName = 'MyCompany_MyModule_Model_Example_Mocking';

    /**
     * @var MyCompany_MyModule_Model_Example_Mocking
     */
    protected $_instance;

    public function testDoSomething()
    {
        // Build a mock object and register it for the
        // Mage::helper() method with the correct key
        $helper = $this->buildMock('MyCompany_MyModule_Helper_Config');
        $this->addMageHelper('mycompany_mymodule/config', $helper);

        // define configuration value
        $configurationValue = 'unittest value';

        // Method 'getAnyConfigurationValue
        // must be invoked one time
        // and return the value '$configurationValue'
        $helper->expects($this->once())
            ->method('getAnyConfigurationValue')
            ->will($this->returnValue($configurationValue));

        // Method must return the configuration value
        $result = $this->_instance->doSomething();
        $this->assertSame($configurationValue, $result);
    }
}