public function testTransformOnce()
{
$count = 0;
$transformer = new CallbackTransformer(function () use($count) {
return new StringResource('bar' . ++$count);
});
$resource = new StringResource('foo');
$collection = new ResourceCollection([$resource]);
$collection->addTransformer($transformer);
$transformed = $collection->pop();
$this->assertSame('bar1', $transformed->getFile()->fgets());
// add the same resource again
$collection->push($resource);
$transformed = $collection->pop();
$this->assertSame('foo', $transformed->getFile()->fgets(), 'A resource only gets transformed once');
}
