diff --git a/core/modules/syslog/src/Logger/SysLog.php b/core/modules/syslog/src/Logger/SysLog.php
index c2b73de..24250e8 100644
--- a/core/modules/syslog/src/Logger/SysLog.php
+++ b/core/modules/syslog/src/Logger/SysLog.php
@@ -85,6 +85,18 @@ public function log($level, $message, array $context = []) {
       '!message' => strip_tags($message),
     ]);
 
+    $this->syslogWrapper($level, $entry);
+  }
+
+  /**
+   * A syslog wrapper to make syslog functionality testable.
+   *
+   * @param int $level
+   *   The syslog priority.
+   * @param string $entry
+   *   The message to send to syslog function.
+   */
+  protected function syslogWrapper($level, $entry) {
     syslog($level, $entry);
   }
 
diff --git a/core/modules/syslog/tests/modules/syslog_test/src/Logger/SysLogTest.php b/core/modules/syslog/tests/modules/syslog_test/src/Logger/SysLogTest.php
new file mode 100644
index 0000000..c7abeb0
--- /dev/null
+++ b/core/modules/syslog/tests/modules/syslog_test/src/Logger/SysLogTest.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace Drupal\syslog_test\Logger;
+
+use Drupal\syslog\Logger\SysLog;
+use Psr\Log\LoggerInterface;
+
+/**
+ * Redirects logging messages to error_log.
+ */
+class SysLogTest extends SysLog implements LoggerInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function syslogWrapper($level, $entry) {
+    $log_path = \Drupal::service('file_system')->realpath('public://syslog.log');
+    error_log($entry . PHP_EOL, 3, $log_path);
+  }
+
+}
diff --git a/core/modules/syslog/tests/modules/syslog_test/syslog_test.info.yml b/core/modules/syslog/tests/modules/syslog_test/syslog_test.info.yml
new file mode 100644
index 0000000..9a0bec7
--- /dev/null
+++ b/core/modules/syslog/tests/modules/syslog_test/syslog_test.info.yml
@@ -0,0 +1,8 @@
+name: 'Syslog test'
+type: module
+description: 'Provides a test logger for syslog module.'
+package: Testing
+version: VERSION
+core: 8.x
+dependencies:
+  - syslog
diff --git a/core/modules/syslog/tests/modules/syslog_test/syslog_test.services.yml b/core/modules/syslog/tests/modules/syslog_test/syslog_test.services.yml
new file mode 100644
index 0000000..120387b
--- /dev/null
+++ b/core/modules/syslog/tests/modules/syslog_test/syslog_test.services.yml
@@ -0,0 +1,7 @@
+services:
+  logger.syslog_test:
+    parent: logger.syslog
+    class: Drupal\syslog_test\Logger\SysLogTest
+    arguments: ['@config.factory', '@logger.log_message_parser']
+    tags:
+      - { name: logger }
diff --git a/core/modules/syslog/tests/src/Functional/SyslogTest.php b/core/modules/syslog/tests/src/Functional/SyslogTest.php
index 11b577f..7753c89 100644
--- a/core/modules/syslog/tests/src/Functional/SyslogTest.php
+++ b/core/modules/syslog/tests/src/Functional/SyslogTest.php
@@ -16,7 +16,7 @@ class SyslogTest extends BrowserTestBase {
    *
    * @var array
    */
-  public static $modules = ['syslog'];
+  public static $modules = ['syslog', 'syslog_test'];
 
   /**
    * Tests the syslog settings page.
@@ -37,4 +37,54 @@ public function testSettings() {
     }
   }
 
+  /**
+   * Test the syslog writing functionality.
+   */
+  public function testSyslogWriting() {
+    \Drupal::logger('my_module')->warning('My warning message.');
+    $this->drupalGet('/page-not-found');
+
+    global $base_url;
+
+    $log_filename = $this->container->get('file_system')->realpath('public://syslog.log');
+
+    $content = file_get_contents($log_filename);
+    $rows = explode(PHP_EOL, $content);
+    $this->assertTrue(count($rows) > 1);
+
+    $first_log_found = $second_log_found = $third_log_found = FALSE;
+    foreach ($rows as $row) {
+      if (strpos($row, 'syslog_test module installed.') !== FALSE) {
+        $log_items = explode('|', $row);
+        $expected = [$base_url, 'system', 'syslog_test module installed.'];
+        foreach ($expected as $value) {
+          $this->assertContains($value, $log_items);
+        }
+        $first_log_found = TRUE;
+      }
+
+      if (strpos($row, 'my_module') !== FALSE) {
+        $log_items = explode('|', $row);
+        $expected = [$base_url, 'my_module', 'My warning message.'];
+        foreach ($expected as $value) {
+          $this->assertContains($value, $log_items);
+        }
+        $second_log_found = TRUE;
+      }
+
+      if (strpos($row, 'page not found') !== FALSE) {
+        $log_items = explode('|', $row);
+        $expected = [$base_url, $base_url . '/page-not-found'];
+        foreach ($expected as $value) {
+          $this->assertContains($value, $log_items);
+        }
+        $third_log_found = TRUE;
+      }
+    }
+
+    $this->assertTrue($first_log_found);
+    $this->assertTrue($second_log_found);
+    $this->assertTrue($third_log_found);
+  }
+
 }