trait AssertMailTrait

trait AssertMailTrait {
    
    /**
     * Gets an array containing all emails sent during this test case.
     *
     * @param array $filter
     *   An array containing key/value pairs used to filter the emails that are
     *   returned.
     *
     * @return array
     *   An array containing email messages captured during the current test.
     */
    protected function getMails(array $filter = []) {
        $captured_emails = $this->container
            ->get('state')
            ->get('system.test_mail_collector', []);
        $filtered_emails = [];
        foreach ($captured_emails as $message) {
            foreach ($filter as $key => $value) {
                if (!isset($message[$key]) || $message[$key] != $value) {
                    continue 2;
                }
            }
            $filtered_emails[] = $message;
        }
        return $filtered_emails;
    }
    
    /**
     * Asserts that the most recently sent email message has the given value.
     *
     * The field in $name must have the content described in $value.
     *
     * @param string $name
     *   Name of field or message property to assert. Examples: subject, body,
     *   id, ...
     * @param string $value
     *   Value of the field to assert.
     * @param string $message
     *   (optional) A message to display with the assertion. Do not translate
     *   messages: use \Drupal\Component\Render\FormattableMarkup to embed
     *   variables in the message text, not t(). If left blank, a default message
     *   will be displayed.
     *
     * @return bool
     *   TRUE on pass.
     */
    protected function assertMail($name, $value = '', $message = '') {
        $captured_emails = $this->container
            ->get('state')
            ->get('system.test_mail_collector') ?: [];
        $email = end($captured_emails);
        $this->assertIsArray($email, $message);
        $this->assertArrayHasKey($name, $email, $message);
        $this->assertEquals($value, $email[$name], $message);
        return TRUE;
    }
    
    /**
     * Asserts that the most recently sent email message has the string in it.
     *
     * @param string $field_name
     *   Name of field or message property to assert: subject, body, id, ...
     * @param string $string
     *   String to search for.
     * @param int $email_depth
     *   Number of emails to search for string, starting with most recent.
     * @param string $message
     *   (optional) A message to display with the assertion. Do not translate
     *   messages: use \Drupal\Component\Render\FormattableMarkup to embed
     *   variables in the message text, not t(). If left blank, a default message
     *   will be displayed.
     */
    protected function assertMailString($field_name, $string, $email_depth, $message = '') {
        $mails = $this->getMails();
        $string_found = FALSE;
        // Cast MarkupInterface objects to string.
        $string = (string) $string;
        for ($i = count($mails) - 1; $i >= count($mails) - $email_depth && $i >= 0; $i--) {
            $mail = $mails[$i];
            // Normalize whitespace, as we don't know what the mail system might have
            // done. Any run of whitespace becomes a single space.
            $normalized_mail = preg_replace('/\\s+/', ' ', $mail[$field_name]);
            $normalized_string = preg_replace('/\\s+/', ' ', $string);
            $string_found = str_contains($normalized_mail, $normalized_string);
            if ($string_found) {
                break;
            }
        }
        if (!$message) {
            $message = new FormattableMarkup('Expected text found in @field of email message: "@expected".', [
                '@field' => $field_name,
                '@expected' => $string,
            ]);
        }
        $this->assertTrue($string_found, $message);
    }
    
    /**
     * Asserts that the most recently sent email message has the pattern in it.
     *
     * @param string $field_name
     *   Name of field or message property to assert: subject, body, id, ...
     * @param string $regex
     *   Pattern to search for.
     * @param string $message
     *   (optional) A message to display with the assertion. Do not translate
     *   messages: use \Drupal\Component\Render\FormattableMarkup to embed
     *   variables in the message text, not t(). If left blank, a default message
     *   will be displayed.
     */
    protected function assertMailPattern($field_name, $regex, $message = '') {
        $mails = $this->getMails();
        $mail = end($mails);
        $regex_found = preg_match("/{$regex}/", $mail[$field_name]);
        if (!$message) {
            $message = new FormattableMarkup('Expected text found in @field of email message: "@expected".', [
                '@field' => $field_name,
                '@expected' => $regex,
            ]);
        }
        $this->assertTrue((bool) $regex_found, $message);
    }

}