diff --git a/tests/src/Functional/LangCodeTest.php b/tests/src/Functional/LangCodeTest.php
index fd913a90ed..a674b69eeb 100644
--- a/tests/src/Functional/LangCodeTest.php
+++ b/tests/src/Functional/LangCodeTest.php
@@ -30,7 +30,7 @@ class LangCodeTest extends BrowserTestBase {
    *
    * @var array
    */
-  public static $modules = [
+  protected static $modules = [
     'node',
     'search',
     'porterstemmer',
@@ -77,7 +77,7 @@ class LangCodeTest extends BrowserTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp():void {
     parent::setUp();
 
     $this->testUser = $this->drupalCreateUser([
diff --git a/tests/src/Unit/Porter2Pecl1.php b/tests/src/Unit/Porter2Pecl1.php
index 54a8ebe335..9600aeecf5 100644
--- a/tests/src/Unit/Porter2Pecl1.php
+++ b/tests/src/Unit/Porter2Pecl1.php
@@ -23,7 +23,7 @@ public function testStem($word, $stem) {
       $this->assertEquals($stem, stem_english($word));
     }
     else {
-      $this->assertTrue(TRUE, 'No PECL stem library found, Aborting test.');
+      $this->assertTrue('No PECL stem library found, Aborting test.');
     }
   }
 
diff --git a/tests/src/Unit/Porter2Pecl2.php b/tests/src/Unit/Porter2Pecl2.php
index c4f1fcc29a..56fdc1d5cb 100644
--- a/tests/src/Unit/Porter2Pecl2.php
+++ b/tests/src/Unit/Porter2Pecl2.php
@@ -23,7 +23,7 @@ public function testStem($word, $stem) {
       $this->assertEquals($stem, stem_english($word));
     }
     else {
-      $this->assertTrue(TRUE, 'No PECL stem library found, Aborting test.');
+      $this->assertTrue('No PECL stem library found, Aborting test.');
     }
   }
 
diff --git a/tests/src/Unit/Porter2Pecl3.php b/tests/src/Unit/Porter2Pecl3.php
index 96b1e22033..d307b8d507 100644
--- a/tests/src/Unit/Porter2Pecl3.php
+++ b/tests/src/Unit/Porter2Pecl3.php
@@ -23,7 +23,7 @@ public function testStem($word, $stem) {
       $this->assertEquals($stem, stem_english($word));
     }
     else {
-      $this->assertTrue(TRUE, 'No PECL stem library found, Aborting test.');
+      $this->assertTrue('No PECL stem library found, Aborting test.');
     }
   }
 
diff --git a/tests/src/Unit/Porter2Pecl4.php b/tests/src/Unit/Porter2Pecl4.php
index b1bfba2aee..9afc0122ce 100644
--- a/tests/src/Unit/Porter2Pecl4.php
+++ b/tests/src/Unit/Porter2Pecl4.php
@@ -23,7 +23,7 @@ public function testStem($word, $stem) {
       $this->assertEquals($stem, stem_english($word));
     }
     else {
-      $this->assertTrue(TRUE, 'No PECL stem library found, Aborting test.');
+      $this->assertTrue('No PECL stem library found, Aborting test.');
     }
   }
 
diff --git a/tests/src/Unit/Porter2Pecl5.php b/tests/src/Unit/Porter2Pecl5.php
index 8a3c4eb327..e4de6b9168 100644
--- a/tests/src/Unit/Porter2Pecl5.php
+++ b/tests/src/Unit/Porter2Pecl5.php
@@ -23,7 +23,7 @@ public function testStem($word, $stem) {
       $this->assertEquals($stem, stem_english($word));
     }
     else {
-      $this->assertTrue(TRUE, 'No PECL stem library found, Aborting test.');
+      $this->assertTrue('No PECL stem library found, Aborting test.');
     }
   }
 
diff --git a/tests/src/Unit/Porter2Pecl6.php b/tests/src/Unit/Porter2Pecl6.php
index 56608aa20b..5ed898d4c4 100644
--- a/tests/src/Unit/Porter2Pecl6.php
+++ b/tests/src/Unit/Porter2Pecl6.php
@@ -23,7 +23,7 @@ public function testStem($word, $stem) {
       $this->assertEquals($stem, stem_english($word));
     }
     else {
-      $this->assertTrue(TRUE, 'No PECL stem library found, Aborting test.');
+      $this->assertTrue('No PECL stem library found, Aborting test.');
     }
   }
 
diff --git a/tests/src/Unit/PorterPeclBase.php b/tests/src/Unit/PorterPeclBase.php
index e78eb93957..a466c4c21d 100644
--- a/tests/src/Unit/PorterPeclBase.php
+++ b/tests/src/Unit/PorterPeclBase.php
@@ -16,7 +16,7 @@ abstract class PorterPeclBase extends UnitTestCase {
    *
    * @var array
    */
-  public static $modules = ['porterstemmer'];
+  protected static $modules = ['porterstemmer'];
 
   /**
    * Whether or not we have the PECL stem extension.