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Testing Configuration

When to Use

Testing config schema, config import/export, default config, config overrides.

Decision

Config aspect Test approach Test type
Config schema valid SchemaCheckTestTrait Kernel
Config values correct after install Load config, assert values Kernel
Config form saves correctly Submit form, load config Browser
Config overrides work Test with settings.php override Kernel

Pattern

Testing config schema (Kernel): 

namespace Drupal\Tests\my_module\Kernel;

use Drupal\KernelTests\KernelTestBase;

class ConfigSchemaTest extends KernelTestBase {

  use SchemaCheckTestTrait;

  protected static $modules = ['my_module'];

  public function testConfigSchema(): void {
    $config = $this->config('my_module.settings');
    $this->assertConfigSchema(
      $this->getConfigSchemaChecker(),
      'my_module.settings',
      $config->get()
    );
  }
}

Testing default config values: 

public function testDefaultConfig(): void {
  $this->installConfig(['my_module']);
  $config = $this->config('my_module.settings');

  $this->assertEquals('default_value', $config->get('setting_key'));
  $this->assertEquals(10, $config->get('numeric_setting'));
}

Testing config form (Browser): 

namespace Drupal\Tests\my_module\Functional;

use Drupal\Tests\BrowserTestBase;

class ConfigFormTest extends BrowserTestBase {

  protected $defaultTheme = 'stark';
  protected static $modules = ['my_module'];

  public function testConfigForm(): void {
    $admin = $this->drupalCreateUser(['administer site configuration']);
    $this->drupalLogin($admin);

    $this->drupalGet('admin/config/my-module');
    $this->submitForm(['setting_key' => 'new_value'], 'Save configuration');

    $config = $this->config('my_module.settings');
    $this->assertEquals('new_value', $config->get('setting_key'));
  }
}

Testing config overrides: 

public function testConfigOverride(): void {
  $this->config('my_module.settings')
    ->set('overridable_value', 'original')
    ->save();

  // Override in test
  $settings = Settings::getAll();
  $settings['my_module.settings']['overridable_value'] = 'overridden';
  new Settings($settings);

  $config = $this->config('my_module.settings');
  $this->assertEquals('overridden', $config->get('overridable_value'));
}

Reference: /core/modules/system/tests/src/Kernel/System/

Common Mistakes

  • Not calling installConfig() before testing config -- config doesn't exist
  • Testing editable config in Unit tests -- config system needs container (use Kernel)
  • Not validating config schema -- invalid config accepted, breaks site later
  • Forgetting to clear cache after config changes -- tests see stale values
  • Not testing config dependencies -- module uninstall leaves orphaned config

See Also