Testing Abstract Document Repository which interacts with MongoDB

Question

Heey all,

I'm having troubles to set up a testcase. I have a plain symfony 3 project connected to mongodb. I have multiple documents which each needs an extra method to query the database. The method will get the last document inserted in the collection and is called findLatestInserted().

This specific function was duplicated in each document repository. So I decided to extract it and create a class BaseDocumentRepository which extends the default DocumentRepository. All of my document repositories still have their own DocumentRepository class let's say: CpuInfoRepository, RamInfoRepository. These classes do offer a few extra methods to query the mongodb database and the one in common: findLatestInserted()

It all works fine but just in case i'd wanted to write a unit test for this method findLatestInserted().

I have a test database called prototyping-test which is used to create a document and query it and check the result. Afterwards it'll clear itself so no documents stays in. For each repository there's a specific url to post data to to create a file in the database. To create a CpuInfo collection you'll post data to http://localhost:8000/ServerInfo/CreateCpuInfo. To create a RamInfo collection you'll post data to http://localhost:8000/ServerInfo/CreateRamInfo.

So here follows my question how would i write a test to test the method findLatestInserted()?

this is what i've tried so far:

public function testFindLatestInserted()
{
    $client = self::createClient();
    $crawler = $client->request('POST',
        '/ServerInfo/CreateCpuInfo',
        [
            "hostname" => $this->hostname,
            "timestamp" => $this->timestamp,
            "cpuCores" => $this->cpuCores,
            "cpu1" => $this->cpu1,
            "cpu2" => $this->cpu2
        ]);
    $this->assertTrue($client->getResponse()->isSuccessful());

    $serializer = $this->container->get('jms_serializer');
    $cpuInfo = $serializer->deserialize($client->getResponse()->getContent(), 'AppBundle\Document\CpuInfo', 'json');

    $expected = $this->dm->getRepository("AppBundle:CpuInfo")->find($cpuInfo->getId());
    $stub = $this->getMockForAbstractClass('BaseDocumentRepository');

    $actual = $this->dm
        ->getRepository('AppBundle:CpuInfo')
        ->findLatestInserted();

    $this->assertNotNull($actual);
    $this->assertEquals($expected, $actual);
}

At the line $actual = $this->dm->getRepository('AppBundle:CpuInfo')->findLatestInserted(); i got stuck. As this would only test for CpuInfo while there is RamInfo too (and some other classes not mentioned here). How would one approach this setting? I specificly want to test the method findLatestInserted() on the level of the abstract class instead of the concrete classes.

Please help me out!

Answer 1

Instead of testing the whole stack, just concentrate on testing findLatestInserted() in concrete classes.

Inject MondoDB stub into AppBundle:CpuInfo and check if findLatestInserted() returns expected value. Do the same for AppBundle:RamInfo.

Avoid testing abstract classes, always test concrete classes. In future, you may decide not to inherit from BaseDocumentRepository and may not notice that new implementation of findLatestInserted() fails.