System tests

System tests files are in tests/PHPUnit/System/*Test.php

System tests allow testing how major Matomo components interact together. A test will typically generate hits to the Tracker (record visits and page views) and then test all API responses and for each API output. It then checks that they match expected XML (or CSV, json, etc.). If a test fails, you can compare the processed/ and expected/ directories in a graphical text compare tool, such as WinMerge on Win, or MELD on Linux, or even with PhpStorm, to easily view changes between files.

For example using Meld, click on "Start new comparison", "Directory comparison", in "Original" select "path/to/matomo/tests/PHPUnit/System/expected" in "Mine" select "path/to/matomo/tests/PHPUnit/System/processed"

If changes are expected due to the code changes you make, simply copy the file from processed/ to expected/, and test will then pass. Copying files is done easily using Meld (ALT+LEFT). Otherwise, if you didn't expect to modify the API outputs, it might be that your changes are breaking some features unexpectedly.

Fixtures for System tests

System tests use Fixtures to generate controlled web usage data (visits, goals, pageviews, events, site searches, content tracking, custom variables, etc.).

Fixtures are stored in tests/PHPUnit/Fixtures


We also have an OmniFixture that includes all other Fixtures. OmniFixture is used for screenshot tests to provide data across most reports.

Keep OmniFixture up to date

Remember to update the Omnifixture SQL dump whenever you make any change to any fixture. You can use:

./console tests:setup-fixture OmniFixture --sqldump=OmniFixture-dump.sql

Keeping the OmniFixture up to date makes it easier to see which tests fail after each small fixture change.

If we don't update the OmniFixture then we end up with many failed screenshots tests which makes it hard to see whether those changes are expected or not.

Scheduled Reports Tests

As part of our system tests we generate the scheduled reports (in HTML, PDF & SMS). Some of these scheduled reports contain PNG graphs. Depending on the system under test, generated images can differ. Therefore, PNG graphs are only tested and compared against "expected" graphs, if the system under test has the same characteristics as the integration server. The characteristics of the integration server are described in SystemTestCase::canImagesBeIncludedInScheduledReports()

Writing system tests

To create a system test, extends Piwik\Tests\Framework\TestCase\SystemTestCase. Then implement the getApiForTesting() method. This method should return an array of arrays. Each nested array contains information for a single test.

The first element in the array should be one or more API methods or the 'all' string. This determines which API methods whose output should be compared against expected files. The second element should be an associative array that contains a set of options that affect the way the test is run or URL used to invoke the API method. You are allowed to set the following options:

  • testSuffix: The suffix added to the output file name. If you call a single API method more than once in a system test, all but one of them should have a testSuffix set so different output files will be created.
  • format: The desired format of the output. Defaults to 'xml'. The extension of the output is determined by the format.
  • idSite: The ID of the website to get data for or 'all'.
  • date: The date to get data for.
  • periods: The period or periods to get data for. Can be an array. For example, 'day' or array('day', 'month').
  • setDateLastN: Flag describing whether to query for a set of dates or not.
  • language: The language to use.
  • segment: The segment to use.
  • idGoal: Sets the idGoal query parameter to this value.
  • apiModule: The value to use in the apiModule request parameter.
  • apiAction: The value to use in the apiAction request parameter.
  • otherRequestParameters: An array of extra request parameters to use.
  • disableArchiving: If true, disables archiving before running tests.

Some examples:

public function getApiForTesting()
    $idSite = self::$fixture->idSite;
    $dateTime = self::$fixture->dateTime;

    return array(
        // test a single API method
        array('UserSettings.getResolution', array('idSite' => $idSite, 'date' => $dateTime)),

        // test all methods in a plugin
        array('API', array('idSite' => $idSite, 'date' => $dateTime)),

        // test every API method
        array('all', array('idSite' => $idSite, 'date' => $dateTime)),

        // set some custom request parameters
        array('API.getBulkRequest', array('format' => 'xml',
                                          'testSuffix' => '_bulk_xml',
                                          'otherRequestParameters' => array('urls' => $bulkUrls))),

        // test multiple dates w/ multiple periods and multiple sites
        array('UserSettings.getResolution', array('idSite' => 'all',
                                                  'date' => $dateTime,
                                                  'periods' => array('day', 'week', 'month'),
                                                  'setDateLastN' => true)),

After implementing getApiForTesting(), add the following test to the file:

 * @dataProvider getApiForTesting
 * @group        System
public function testApi($api, $params)
    $this->runApiTests($api, $params);

This will test every API method specified in getApiForTesting().


Before you can run your tests, you'll have to set the test's fixture. Fixtures add test data to the database by adding websites, tracking visits, etc.

To set a fixture, add a public static field named $fixture to your test class and initialize it below the class definition, for example:

namespace Piwik\Plugins\MyPlugin\Test;

use Piwik\Tests\Framework\TestCase\SystemTestCase;

class MySystemTest extends SystemTestCase
    public static $fixture = null;

    // ...

MySystemTest::$fixture = new \Test_Piwik_Fixture_ThreeGoalsOnePageview();

To see the fixtures Matomo (formerly Piwik) defines, see the files in the tests/PHPUnit/Fixtures directory.

You can create your own fixture as well, just extend Piwik\Tests\Framework\Fixture and place the file in the Test/Fixtures/ directory of your plugin.

Expected and processed output

System tests will generate an expected output file for every API method and period combination. The generated output (also called processed output) is stored in the processed/ subdirectory of your plugin's Test/ directory. The expected output should be stored in a directory named expected/.

When you first create a system test, there will be no expected files. You will have to copy processed files to the expected folder after ensuring they are correct.

Downloading processed files from GitHub actions to fix system tests

When you work on a bug or feature and you push the code to GitHub then an action will run our system tests. You might then notice that some system tests are failing because the expected content is different to the processed content. To not having to run the all the tests locally and as the GitHub action might include different plugins it's recommended to download the processed files from GitHub and then committing these to make the tests pass. However, it is very much needed to look at each changed file and assess that the changed content is expected. This can be done for example before pushing the changes.

To download the processed files from system tests execute below command. You will need to replace {BUILD_NUMBER} with the number of the build. You find this number when you select a build in GitHub Actions. The build number is part of the URL. e.g.{BUILD_NUMBER}/.

./console development:sync-system-test-processed {BUILD_NUMBER} --expected

This will download all the processed system test results and copies them directly into the expected system test directories. Next you can git add and commit and push them. Before adding or pushing make sure though that all the changes are expected.

Alternatively, you can also remove the --expected option in which case it will copy the downloaded files into your processed filter. You can then use for example the "Compare directories" feature in PHPStorm and only copy over the processed files into the expected directory where the changes are expected.


Only generated N API calls to test but was expecting more for this test.

Sometimes when writing a test you'll see this error in the test output:

Only generated N API calls to test but was expecting more for this test
Want to test APIs: ...
But only generated these URLs:

This can have the following possible causes:

How to adjust metadata tests to only include the data from their plugin

When running system tests that fetch data from API.getReportMetadata, API.getSegmentsMetadata, API.getReportPagesMetadata or API.getWidgetMetadata, the API response includes results from all other plugins. This can make it hard to maintain a passing build as tests might fail because of a change in a different plugin. To limit the response to the current plugin you can use the below example code.

class ApiTest extends SystemTestCase
  public static function setUpBeforeClass(): void
    self::setAllowedModulesToFilterApiResponse('API.getReportMetadata', array('MODULES_TO_FILTER'));
    self::setAllowedCategoriesToFilterApiResponse('API.getSegmentsMetadata', array('CATEGORIES_TO_FILTER'));
    self::setAllowedModulesToFilterApiResponse('API.getWidgetMetadata', array('MODULES_TO_FILTER'));
    self::setAllowedCategoriesToFilterApiResponse('API.getReportPagesMetadata', array('CATEGORIES_TO_FILTER'));

Writing tests for commands

It is also possible to write system tests for console commands. These tests should extend Piwik\Tests\Framework\TestCase\ConsoleCommandTestCase.

Example for a test that tests the config:set command:

class MyCommandTest extends \Piwik\Tests\Framework\TestCase\ConsoleCommandTestCase

    public function test_command_succeedsWhenOptionsUsed()
        // execute the command with few different options
        $code = $this->applicationTester->run(array(
            'command' => 'config:set',
            '--section' => 'MySection',
            '--key' => 'setting',
            '--value' => 'myvalue',
            '-vvv' => false,

        // assert exit code
        $this->assertEquals(0, $code, $this->getCommandDisplayOutputErrorMessage()); 

        // assert the command actually performed the correct action
        $config = $this->makeNewConfig();
        $this->assertEquals(array('setting' => 'myvalue'), $config->MySection);

        // assert printed command output
        self::assertStringContainsString('Setting [MySection] setting = "myvalue"', $this->applicationTester->getDisplay());