public function testAddPrefix() {
$loader = new ClassLoader();
$loader
->addPrefix('Foo', __DIR__ . DIRECTORY_SEPARATOR . 'Fixtures');
$loader
->addPrefix('Foo', __DIR__ . DIRECTORY_SEPARATOR . 'Fixtures');
$prefixes = $loader
->getPrefixes();
$this
->assertArrayHasKey('Foo', $prefixes);
$this
->assertCount(2, $prefixes['Foo']);
}