public function testDefaultServiceInstantiation() {
    // Check all services in the default instance, not a dummy instance!
    // Note that we instantiate all services here, including any that
    // were registered by extensions.
    $services = MediaWikiServices::getInstance();
    $names = $services->getServiceNames();

    foreach ( $names as $name ) {
        $this->assertTrue( $services->hasService( $name ) );
        $service = $services->getService( $name );
        $this->assertIsObject( $service );
    }
}

php tests/phpunit/phpunit.php tests/phpunit/includes/MediaWikiServicesTest.php --filter "testDefaultServiceInstantiation"

PHPUnit 8.5.21 by Sebastian Bergmann and contributors.

E                                                                   1 / 1 (100%)

Time: 1.63 seconds, Memory: 50.50 MB

There was 1 error:

1) MediaWikiServicesTest::testDefaultServiceInstantiation
Error: Call to a member function inNamespace() on null

/Users/kostajh/src/mediawiki/w/skins/MinervaNeue/includes/ServiceWiring.php:93
/Users/kostajh/src/mediawiki/w/vendor/wikimedia/services/src/ServiceContainer.php:447
/Users/kostajh/src/mediawiki/w/vendor/wikimedia/services/src/ServiceContainer.php:416
/Users/kostajh/src/mediawiki/w/includes/MediaWikiServices.php:291
/Users/kostajh/src/mediawiki/w/tests/phpunit/includes/MediaWikiServicesTest.php:386
/Users/kostajh/src/mediawiki/w/tests/phpunit/MediaWikiIntegrationTestCase.php:456

ERRORS!
Tests: 1, Assertions: 9, Errors: 1.