diff --git a/tests/phpunit/tests/attachment/slashes.php b/tests/phpunit/tests/attachment/slashes.php
index 082efb110e59..14bf7d401784 100644
--- a/tests/phpunit/tests/attachment/slashes.php
+++ b/tests/phpunit/tests/attachment/slashes.php
@@ -6,10 +6,16 @@
  * @ticket 21767
  */
 class Tests_Attachment_Slashes extends WP_UnitTestCase {
+	protected static $author_id;
+
+	public static function wpSetUpBeforeClass( $factory ) {
+		self::$author_id = $factory->user->create( array( 'role' => 'editor' ) );
+	}
+
 	function setUp() {
 		parent::setUp();
-		$this->author_id = self::factory()->user->create( array( 'role' => 'editor' ) );
-		wp_set_current_user( $this->author_id );
+
+		wp_set_current_user( self::$author_id );
 
 		// It is important to test with both even and odd numbered slashes,
 		// as KSES does a strip-then-add slashes in some of its function calls.
diff --git a/tests/phpunit/tests/comment/slashes.php b/tests/phpunit/tests/comment/slashes.php
index 8fab42b99735..d6370c342e41 100644
--- a/tests/phpunit/tests/comment/slashes.php
+++ b/tests/phpunit/tests/comment/slashes.php
@@ -6,11 +6,17 @@
  * @ticket 21767
  */
 class Tests_Comment_Slashes extends WP_UnitTestCase {
+	protected static $author_id;
+
+	public static function wpSetUpBeforeClass( $factory ) {
+		// We need an admin user to bypass comment flood protection.
+		self::$author_id = $factory->user->create( array( 'role' => 'administrator' ) );
+	}
+
 	function setUp() {
 		parent::setUp();
-		// We need an admin user to bypass comment flood protection.
-		$this->author_id = self::factory()->user->create( array( 'role' => 'administrator' ) );
-		wp_set_current_user( $this->author_id );
+
+		wp_set_current_user( self::$author_id );
 
 		// It is important to test with both even and odd numbered slashes,
 		// as KSES does a strip-then-add slashes in some of its function calls.
diff --git a/tests/phpunit/tests/option/slashes.php b/tests/phpunit/tests/option/slashes.php
index 20220e5d58cd..8d7491fe7635 100644
--- a/tests/phpunit/tests/option/slashes.php
+++ b/tests/phpunit/tests/option/slashes.php
@@ -6,8 +6,10 @@
  * @ticket 21767
  */
 class Tests_Option_Slashes extends WP_UnitTestCase {
+
 	function setUp() {
 		parent::setUp();
+
 		// It is important to test with both even and odd numbered slashes,
 		// as KSES does a strip-then-add slashes in some of its function calls.
 		$this->slash_1 = 'String with 1 slash \\';
diff --git a/tests/phpunit/tests/post/slashes.php b/tests/phpunit/tests/post/slashes.php
index 229ec29aa2f8..bc8b1d8dc002 100644
--- a/tests/phpunit/tests/post/slashes.php
+++ b/tests/phpunit/tests/post/slashes.php
@@ -6,11 +6,16 @@
  * @ticket 21767
  */
 class Tests_Post_Slashes extends WP_UnitTestCase {
+	protected static $author_id;
+
+	public static function wpSetUpBeforeClass( $factory ) {
+		self::$author_id = $factory->user->create( array( 'role' => 'editor' ) );
+	}
+
 	function setUp() {
 		parent::setUp();
-		$this->author_id = self::factory()->user->create( array( 'role' => 'editor' ) );
 
-		wp_set_current_user( $this->author_id );
+		wp_set_current_user( self::$author_id );
 
 		// It is important to test with both even and odd numbered slashes,
 		// as KSES does a strip-then-add slashes in some of its function calls.
diff --git a/tests/phpunit/tests/term/slashes.php b/tests/phpunit/tests/term/slashes.php
index ea04097bbee3..967e4834bdb5 100644
--- a/tests/phpunit/tests/term/slashes.php
+++ b/tests/phpunit/tests/term/slashes.php
@@ -6,11 +6,16 @@
  * @ticket 21767
  */
 class Tests_Term_Slashes extends WP_Ajax_UnitTestCase {
+	protected static $author_id;
+
+	public static function wpSetUpBeforeClass( $factory ) {
+		self::$author_id = $factory->user->create( array( 'role' => 'administrator' ) );
+	}
+
 	function setUp() {
 		parent::setUp();
-		$this->author_id = self::factory()->user->create( array( 'role' => 'administrator' ) );
 
-		wp_set_current_user( $this->author_id );
+		wp_set_current_user( self::$author_id );
 
 		$this->slash_1 = 'String with 1 slash \\';
 		$this->slash_2 = 'String with 2 slashes \\\\';
diff --git a/tests/phpunit/tests/user/slashes.php b/tests/phpunit/tests/user/slashes.php
index e5675abb5d7b..87def324af30 100644
--- a/tests/phpunit/tests/user/slashes.php
+++ b/tests/phpunit/tests/user/slashes.php
@@ -6,11 +6,16 @@
  * @ticket 21767
  */
 class Tests_User_Slashes extends WP_UnitTestCase {
+	protected static $author_id;
+
+	public static function wpSetUpBeforeClass( $factory ) {
+		self::$author_id = $factory->user->create( array( 'role' => 'administrator' ) );
+	}
+
 	function setUp() {
 		parent::setUp();
-		$this->author_id = self::factory()->user->create( array( 'role' => 'administrator' ) );
 
-		wp_set_current_user( $this->author_id );
+		wp_set_current_user( self::$author_id );
 
 		// It is important to test with both even and odd numbered slashes,
 		// as KSES does a strip-then-add slashes in some of its function calls.