How to Use the Profiler in a Functional Test

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It's highly recommended that a functional test only tests the Response. But if you write functional tests that monitor your production servers, you might want to write tests on the profiling data as it gives you a great way to check various things and enforce some metrics.

The Symfony Profiler gathers a lot of data for each request. Use this data to check the number of database calls, the time spent in the framework, etc. But before writing assertions, enable the profiler and check that the profiler is indeed available (it is enabled by default in the test environment):

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class HelloControllerTest extends WebTestCase
{
    public function testIndex()
    {
        $client = static::createClient();

        // enable the profiler only for the next request (if you make
        // new requests, you must call this method again)
        // (it does nothing if the profiler is not available)
        $client->enableProfiler();

        $crawler = $client->request('GET', '/hello/Fabien');

        // ... write some assertions about the Response

        // check that the profiler is enabled
        if ($profile = $client->getProfile()) {
            // check the number of requests
            $this->assertLessThan(
                10,
                $profile->getCollector('db')->getQueryCount()
            );

            // check the time spent in the framework
            $this->assertLessThan(
                500,
                $profile->getCollector('time')->getDuration()
            );
        }
    }
}

If a test fails because of profiling data (too many DB queries for instance), you might want to use the Web Profiler to analyze the request after the tests finish. It's easy to achieve if you embed the token in the error message:

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$this->assertLessThan(
    30,
    $profile->getCollector('db')->getQueryCount(),
    sprintf(
        'Checks that query count is less than 30 (token %s)',
        $profile->getToken()
    )
);

Caution

The profiler store can be different depending on the environment (especially if you use the SQLite store, which is the default configured one).

Note

The profiler information is available even if you insulate the client or if you use an HTTP layer for your tests.

Tip

Read the API for built-in data collectors to learn more about their interfaces.

Speeding up Tests by not Collecting Profiler Data

To avoid collecting data in each test you can set the collect parameter to false:

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# app/config/config_test.yml

# ...
framework:
    profiler:
        enabled: true
        collect: false

In this way only tests that call $client->enableProfiler() will collect data.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.
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