diff --git a/core/tests/Drupal/Tests/Core/Form/FormStateDecoratorBaseTest.php b/core/tests/Drupal/Tests/Core/Form/FormStateDecoratorBaseTest.php
index 6c877b5406d175ef7082034ed50d9569024ce48e..2b00dfdfa1a6e38d86c7870d62dacf77448232a8 100644
--- a/core/tests/Drupal/Tests/Core/Form/FormStateDecoratorBaseTest.php
+++ b/core/tests/Drupal/Tests/Core/Form/FormStateDecoratorBaseTest.php
@@ -950,7 +950,7 @@ public function testSet($key, $value) {
   /**
    * Provides data to self::testSet().
    */
-  public function providerSet() {
+  public static function providerSet(): array {
     return [
       ['FOO', 'BAR'],
       ['FOO', NULL],
@@ -987,7 +987,7 @@ public function testGet($key, $value = NULL) {
   /**
    * Provides data to self::testGet().
    */
-  public function providerGet() {
+  public static function providerGet(): array {
     return [
       ['FOO', 'BAR'],
       ['FOO', NULL],
@@ -1017,7 +1017,7 @@ public function testHas($exists, $key) {
   /**
    * Provides data to self::testHas().
    */
-  public function providerHas() {
+  public static function providerHas(): array {
     return [
       [TRUE, 'FOO'],
       [FALSE, 'FOO'],
@@ -1445,13 +1445,13 @@ public function testPrepareCallback($unprepared_callback, callable $prepared_cal
   /**
    * Provides data to self::testPrepareCallback().
    */
-  public function providerPrepareCallback() {
+  public static function providerPrepareCallback(): array {
     $function = 'sleep';
     $shorthand_form_method = '::submit()';
     $closure = function () {};
     $static_method_string = __METHOD__;
     $static_method_array = [__CLASS__, __FUNCTION__];
-    $object_method_array = [$this, __FUNCTION__];
+    $object_method_array = [new static(), __FUNCTION__];
 
     return [
       // A shorthand form method is generally expanded to become a method on an
diff --git a/core/tests/Drupal/Tests/Core/Form/SubformStateTest.php b/core/tests/Drupal/Tests/Core/Form/SubformStateTest.php
index 016fa6a19719463acf4ac5d1016cfb186a2b2b9f..6bd6bab57e326b8a3ec6edb8eb0e825a714ba3a9 100644
--- a/core/tests/Drupal/Tests/Core/Form/SubformStateTest.php
+++ b/core/tests/Drupal/Tests/Core/Form/SubformStateTest.php
@@ -24,7 +24,7 @@ class SubformStateTest extends UnitTestCase {
    *
    * @var mixed[]
    */
-  protected $formStateValues = [
+  protected static $formStateValues = [
     'foo' => 'bar',
     'dog' => [
       'breed' => 'Pit bull',
@@ -70,7 +70,7 @@ class SubformStateTest extends UnitTestCase {
    */
   public function testGetValues(array $parents, $expected) {
     $parent_form_state = new FormState();
-    $parent_form_state->setValues($this->formStateValues);
+    $parent_form_state->setValues(static::$formStateValues);
 
     $subform = NestedArray::getValue($this->parentForm, $parents);
     $subform_state = SubformState::createForSubform($subform, $this->parentForm, $parent_form_state);
@@ -86,11 +86,11 @@ public function testGetValues(array $parents, $expected) {
   /**
    * Provides data to self::testGetValues().
    */
-  public function providerGetValues() {
+  public static function providerGetValues(): array {
     $data = [];
     $data['exist'] = [
       ['dog'],
-      $this->formStateValues['dog'],
+      static::$formStateValues['dog'],
     ];
 
     return $data;
@@ -115,11 +115,11 @@ public function testGetValuesBroken(array $parents, $expected) {
   /**
    * Provides data to self::testGetValuesBroken().
    */
-  public function providerGetValuesBroken() {
+  public static function providerGetValuesBroken(): array {
     $data = [];
     $data['exist'] = [
       ['foo'],
-      $this->formStateValues['foo'],
+      static::$formStateValues['foo'],
     ];
     $data['nested'] = [
       ['dog', 'name'],
@@ -136,7 +136,7 @@ public function providerGetValuesBroken() {
    */
   public function testGetValue($parents, $key, $expected, $default = NULL) {
     $parent_form_state = new FormState();
-    $parent_form_state->setValues($this->formStateValues);
+    $parent_form_state->setValues(static::$formStateValues);
 
     $subform = NestedArray::getValue($this->parentForm, $parents);
     $subform_state = SubformState::createForSubform($subform, $this->parentForm, $parent_form_state);
@@ -194,7 +194,7 @@ public static function providerTestGetValueBroken() {
    */
   public function testSetValues($parents, $new_values, $expected) {
     $parent_form_state = new FormState();
-    $parent_form_state->setValues($this->formStateValues);
+    $parent_form_state->setValues(static::$formStateValues);
 
     $subform = NestedArray::getValue($this->parentForm, $parents);
     $subform_state = SubformState::createForSubform($subform, $this->parentForm, $parent_form_state);
@@ -231,14 +231,14 @@ public function testSetValuesBroken($parents, $new_values, $expected) {
   /**
    * Provides data to self::testSetValuesBroken().
    */
-  public function providerTestSetValuesBroken() {
+  public static function providerTestSetValuesBroken(): array {
     $data = [];
     $data['exist'] = [
       ['foo'],
       [],
       [
         'foo' => [],
-        'dog' => $this->formStateValues['dog'],
+        'dog' => static::$formStateValues['dog'],
       ],
     ];
     return $data;