public function testCallStatic()
{
$factory = m::mock('Omnipay\\Common\\GatewayFactory');
$factory->shouldReceive('testMethod')->with('some-argument')->once()->andReturn('some-result');
Omnipay::setFactory($factory);
$result = Omnipay::testMethod('some-argument');
$this->assertSame('some-result', $result);
}