class AssertMailTraitTest

class AssertMailTraitTest extends KernelTestBase {
  use AssertMailTrait;
  
  /**
   * Tests that the maintenance theme initializes the theme and its base themes.
   */
  public function testAssertMailTrait() {
    /** @var \Drupal\Core\Mail\MailManagerInterface $mail_service */
    $mail_service = \Drupal::service('plugin.manager.mail');
    // Create an email.
    $subject = $this->randomString(64);
    $body = $this->randomString(128);
    $message = [
      'id' => 'drupal_mail_test',
      'headers' => [
        'Content-type' => 'text/html',
      ],
      'subject' => $subject,
      'to' => 'foobar@example.com',
      'body' => $body,
    ];
    // Before we send the email, \Drupal\Core\Test\AssertMailTrait::getMails()
    // should return an empty array.
    $captured_emails = $this->getMails();
    $this->assertCount(0, $captured_emails, 'The captured emails queue is empty.');
    // Send the email.
    $mail_service->getInstance([
      'module' => 'simpletest',
      'key' => 'drupal_mail_test',
    ])
      ->mail($message);
    // Ensure that there is one email in the captured emails array.
    $captured_emails = $this->getMails();
    $this->assertCount(1, $captured_emails, 'One email was captured.');
    // Asserts that the message fields have the pattern in it.
    $this->assertMailPattern('id', $message['id']);
    $this->assertMailPattern('subject', "^.{64}\$");
    $this->assertMailPattern('to', "[a-z]{6}@example\\.com\$");
    $this->assertMailPattern('body', "^.{128}\$");
    // Assert that the email was sent by iterating over the message properties
    // and ensuring that they are captured intact.
    foreach ($message as $field => $value) {
      $this->assertMail($field, $value, "The email was sent and the value for property {$field} is intact.");
    }
    // Send additional emails so more than one email is captured.
    for ($index = 0; $index < 5; $index++) {
      $message = [
        'id' => 'drupal_mail_test_' . $index,
        'headers' => [
          'Content-type' => 'text/html',
        ],
        'subject' => $this->randomString(64),
        'to' => $this->randomMachineName(32) . '@example.com',
        'body' => $this->randomString(512),
      ];
      $mail_service->getInstance([
        'module' => 'drupal_mail_test',
        'key' => $index,
      ])
        ->mail($message);
    }
    // There should now be 6 emails captured.
    $captured_emails = $this->getMails();
    $this->assertCount(6, $captured_emails, 'All emails were captured.');
    // Test different ways of getting filtered emails via
    // \Drupal\Core\Test\AssertMailTrait::getMails().
    $captured_emails = $this->getMails([
      'id' => 'drupal_mail_test',
    ]);
    $this->assertCount(1, $captured_emails, 'Only one email is returned when filtering by id.');
    $captured_emails = $this->getMails([
      'id' => 'drupal_mail_test',
      'subject' => $subject,
    ]);
    $this->assertCount(1, $captured_emails, 'Only one email is returned when filtering by id and subject.');
    $captured_emails = $this->getMails([
      'id' => 'drupal_mail_test',
      'subject' => $subject,
      'from' => 'this_was_not_used@example.com',
    ]);
    $this->assertCount(0, $captured_emails, 'No emails are returned when querying with an unused from address.');
    // Send the last email again, so we can confirm that
    // \Drupal\Core\Test\AssertMailTrait::getMails() filters correctly returns
    // all emails with a given property/value.
    $mail_service->getInstance([
      'module' => 'drupal_mail_test',
      'key' => $index,
    ])
      ->mail($message);
    $captured_emails = $this->getMails([
      'id' => 'drupal_mail_test_4',
    ]);
    $this->assertCount(2, $captured_emails, 'All emails with the same id are returned when filtering by id.');
  }

}