diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 70717843640..b174a541811 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -26,6 +26,8 @@ jobs:
           - "8.1"
           - "8.2"
           - "8.3"
+          - "8.4"
+          - "8.5"
         php_invoker: [true, false]
         coverage: [false]
         experimental: [false]
@@ -40,7 +42,7 @@ jobs:
 
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup PHP ${{ matrix.php }}
         uses: shivammathur/setup-php@v2
diff --git a/PHPUnit/Extensions/PhptTestCase.php b/PHPUnit/Extensions/PhptTestCase.php
index ccbe8821228..ddd2eddb112 100644
--- a/PHPUnit/Extensions/PhptTestCase.php
+++ b/PHPUnit/Extensions/PhptTestCase.php
@@ -117,8 +117,12 @@ public function count()
      * @param  array                        $options
      * @return PHPUnit_Framework_TestResult
      */
-    public function run(PHPUnit_Framework_TestResult $result = NULL, array $options = array())
+    public function run($result = NULL, array $options = array())
     {
+        if ($result !== NULL && !$result instanceof PHPUnit_Framework_TestResult) {
+            throw PHPUnit_Util_InvalidArgumentHelper::factory(1, 'PHPUnit_Framework_TestResult');
+        }
+
         if (!class_exists('PEAR_RunTest', FALSE)) {
             $result->addFailure($this, new PHPUnit_Framework_SkippedTestError('PEAR_RunTest not available'), 0);
             return $result;
diff --git a/PHPUnit/Extensions/RepeatedTest.php b/PHPUnit/Extensions/RepeatedTest.php
index ea6dcc5415e..06d35c94c91 100644
--- a/PHPUnit/Extensions/RepeatedTest.php
+++ b/PHPUnit/Extensions/RepeatedTest.php
@@ -129,8 +129,12 @@ public function count()
      * @return PHPUnit_Framework_TestResult
      * @throws PHPUnit_Framework_Exception
      */
-    public function run(PHPUnit_Framework_TestResult $result = NULL)
+    public function run($result = NULL)
     {
+        if ($result !== NULL && !$result instanceof PHPUnit_Framework_TestResult) {
+            throw PHPUnit_Util_InvalidArgumentHelper::factory(1, 'PHPUnit_Framework_TestResult');
+        }
+
         if ($result === NULL) {
             $result = $this->createResult();
         }
diff --git a/PHPUnit/Extensions/TestDecorator.php b/PHPUnit/Extensions/TestDecorator.php
index 18f0b13e9b1..9662064a883 100644
--- a/PHPUnit/Extensions/TestDecorator.php
+++ b/PHPUnit/Extensions/TestDecorator.php
@@ -137,8 +137,12 @@ public function getTest()
      * @param  PHPUnit_Framework_TestResult $result
      * @return PHPUnit_Framework_TestResult
      */
-    public function run(PHPUnit_Framework_TestResult $result = NULL)
+    public function run($result = NULL)
     {
+        if ($result !== NULL && !$result instanceof PHPUnit_Framework_TestResult) {
+            throw PHPUnit_Util_InvalidArgumentHelper::factory(1, 'PHPUnit_Framework_TestResult');
+        }
+
         if ($result === NULL) {
             $result = $this->createResult();
         }
diff --git a/PHPUnit/Framework/Comparator/SplObjectStorage.php b/PHPUnit/Framework/Comparator/SplObjectStorage.php
index aebb7cfec44..e65768f1433 100644
--- a/PHPUnit/Framework/Comparator/SplObjectStorage.php
+++ b/PHPUnit/Framework/Comparator/SplObjectStorage.php
@@ -86,7 +86,7 @@ public function accepts($expected, $actual)
     public function assertEquals($expected, $actual, $delta = 0, $canonicalize = FALSE, $ignoreCase = FALSE)
     {
         foreach ($actual as $object) {
-            if (!$expected->contains($object)) {
+            if (!$expected->offsetExists($object)) {
                 throw new PHPUnit_Framework_ComparisonFailure(
                   $expected,
                   $actual,
@@ -99,7 +99,7 @@ public function assertEquals($expected, $actual, $delta = 0, $canonicalize = FAL
         }
 
         foreach ($expected as $object) {
-            if (!$actual->contains($object)) {
+            if (!$actual->offsetExists($object)) {
                 throw new PHPUnit_Framework_ComparisonFailure(
                   $expected,
                   $actual,
diff --git a/PHPUnit/Framework/Constraint.php b/PHPUnit/Framework/Constraint.php
index ded42147f42..fd7dc116dfb 100644
--- a/PHPUnit/Framework/Constraint.php
+++ b/PHPUnit/Framework/Constraint.php
@@ -126,8 +126,12 @@ public function count()
      * @param  PHPUnit_Framework_ComparisonFailure $comparisonFailure
      * @throws PHPUnit_Framework_ExpectationFailedException
      */
-    protected function fail($other, $description, PHPUnit_Framework_ComparisonFailure $comparisonFailure = NULL)
+    protected function fail($other, $description, $comparisonFailure = NULL)
     {
+        if ($comparisonFailure !== NULL && !$comparisonFailure instanceof PHPUnit_Framework_ComparisonFailure) {
+            throw PHPUnit_Util_InvalidArgumentHelper::factory(3, 'PHPUnit_Framework_ComparisonFailure');
+        }
+
         $failureDescription = sprintf(
           'Failed asserting that %s.',
           $this->failureDescription($other)
diff --git a/PHPUnit/Framework/Constraint/TraversableContains.php b/PHPUnit/Framework/Constraint/TraversableContains.php
index aa00b2dc3ec..2d49d9de807 100644
--- a/PHPUnit/Framework/Constraint/TraversableContains.php
+++ b/PHPUnit/Framework/Constraint/TraversableContains.php
@@ -94,7 +94,7 @@ public function __construct($value, $checkForObjectIdentity = TRUE)
     protected function matches($other)
     {
         if ($other instanceof SplObjectStorage) {
-            return $other->contains($this->value);
+            return $other->offsetExists($this->value);
         }
 
         if (is_object($this->value)) {
diff --git a/PHPUnit/Framework/Error.php b/PHPUnit/Framework/Error.php
index c599e18d2ee..6cd5100ee50 100644
--- a/PHPUnit/Framework/Error.php
+++ b/PHPUnit/Framework/Error.php
@@ -65,8 +65,12 @@ class PHPUnit_Framework_Error extends Exception
      * @param  integer    $line
      * @param  Exception  $previous
      */
-    public function __construct($message, $code, $file, $line, Exception $previous = NULL)
+    public function __construct($message, $code, $file, $line, $previous = NULL)
     {
+        if ($previous !== NULL && !$previous instanceof Exception) {
+            throw PHPUnit_Util_InvalidArgumentHelper::factory(5, 'Exception');
+        }
+
         parent::__construct($message, $code, $previous);
 
         $this->file  = $file;
diff --git a/PHPUnit/Framework/ExpectationFailedException.php b/PHPUnit/Framework/ExpectationFailedException.php
index cdb48cbba3f..9973cf63012 100644
--- a/PHPUnit/Framework/ExpectationFailedException.php
+++ b/PHPUnit/Framework/ExpectationFailedException.php
@@ -65,8 +65,15 @@ class PHPUnit_Framework_ExpectationFailedException extends PHPUnit_Framework_Ass
      */
     protected $comparisonFailure;
 
-    public function __construct($message, PHPUnit_Framework_ComparisonFailure $comparisonFailure = NULL, Exception $previous = NULL)
+    public function __construct($message, $comparisonFailure = NULL, $previous = NULL)
     {
+        if ($comparisonFailure !== NULL && !$comparisonFailure instanceof PHPUnit_Framework_ComparisonFailure) {
+            throw PHPUnit_Util_InvalidArgumentHelper::factory(2, 'PHPUnit_Framework_ComparisonFailure');
+        }
+        if ($previous !== NULL && !$previous instanceof Exception) {
+            throw PHPUnit_Util_InvalidArgumentHelper::factory(3, 'Exception');
+        }
+
         $this->comparisonFailure = $comparisonFailure;
 
         parent::__construct($message, 0, $previous);
diff --git a/PHPUnit/Framework/Test.php b/PHPUnit/Framework/Test.php
index d77af35941a..a198028f9a5 100644
--- a/PHPUnit/Framework/Test.php
+++ b/PHPUnit/Framework/Test.php
@@ -62,5 +62,5 @@ interface PHPUnit_Framework_Test extends Countable
      * @param  PHPUnit_Framework_TestResult $result
      * @return PHPUnit_Framework_TestResult
      */
-    public function run(PHPUnit_Framework_TestResult $result = NULL);
+    public function run($result = NULL);
 }
diff --git a/PHPUnit/Framework/TestCase.php b/PHPUnit/Framework/TestCase.php
index 51ce9ad1289..3fc1e05bbce 100644
--- a/PHPUnit/Framework/TestCase.php
+++ b/PHPUnit/Framework/TestCase.php
@@ -676,8 +676,12 @@ public function hasFailed()
      * @return PHPUnit_Framework_TestResult
      * @throws PHPUnit_Framework_Exception
      */
-    public function run(PHPUnit_Framework_TestResult $result = NULL)
+    public function run($result = NULL)
     {
+        if ($result !== NULL && !$result instanceof PHPUnit_Framework_TestResult) {
+            throw PHPUnit_Util_InvalidArgumentHelper::factory(1, 'PHPUnit_Framework_TestResult');
+        }
+
         if ($result === NULL) {
             $result = $this->createResult();
         }
@@ -1673,21 +1677,29 @@ public static function onConsecutiveCalls()
      * @return string
      * @since  Method available since Release 3.2.1
      */
-    protected function dataToString($data)
+    protected function dataToString($data, $depth = 0)
     {
+        // guard against infinite recursion from self-referencing arrays
+        // that print_r's *RECURSION* detection might miss
+        if ($depth > 25) {
+            return '*DEEP_NESTED*';
+        }
+
         $result = array();
 
         // There seems to be no other way to check arrays for recursion
         // http://www.php.net/manual/en/language.types.array.php#73936
-        preg_match_all('/\n            \[(\w+)\] => Array\s+\*RECURSION\*/', print_r($data, TRUE), $matches);
+        // suppress warnings from NAN/INF string coercion on PHP 8.5+ to avoid
+        // infinite recursion: warning → error handler → dataToString → print_r → warning
+        preg_match_all('/\n            \[(\w+)\] => Array\s+\*RECURSION\*/', @print_r($data, TRUE), $matches);
         $recursiveKeys = array_unique($matches[1]);
 
         // Convert to valid array keys
         // Numeric integer strings are automatically converted to integers
         // by PHP
         foreach ($recursiveKeys as $key => $recursiveKey) {
-            if ((string)(integer)$recursiveKey === $recursiveKey) {
-                $recursiveKeys[$key] = (integer)$recursiveKey;
+            if ((string)(int)$recursiveKey === $recursiveKey) {
+                $recursiveKeys[$key] = (int)$recursiveKey;
             }
         }
 
@@ -1697,7 +1709,7 @@ protected function dataToString($data)
             }
 
             else if (is_array($_data)) {
-                $result[] = 'array(' . $this->dataToString($_data) . ')';
+                $result[] = 'array(' . $this->dataToString($_data, $depth + 1) . ')';
             }
 
             else if (is_object($_data)) {
diff --git a/PHPUnit/Framework/TestSuite.php b/PHPUnit/Framework/TestSuite.php
index 4faad4ace27..4173adc5df8 100644
--- a/PHPUnit/Framework/TestSuite.php
+++ b/PHPUnit/Framework/TestSuite.php
@@ -625,8 +625,12 @@ public function getGroups()
      * @return PHPUnit_Framework_TestResult
      * @throws PHPUnit_Framework_Exception
      */
-    public function run(PHPUnit_Framework_TestResult $result = NULL, $filter = FALSE, array $groups = array(), array $excludeGroups = array(), $processIsolation = FALSE)
+    public function run($result = NULL, $filter = FALSE, array $groups = array(), array $excludeGroups = array(), $processIsolation = FALSE)
     {
+        if ($result !== NULL && !$result instanceof PHPUnit_Framework_TestResult) {
+            throw PHPUnit_Util_InvalidArgumentHelper::factory(1, 'PHPUnit_Framework_TestResult');
+        }
+
         if ($result === NULL) {
             $result = $this->createResult();
         }
@@ -690,7 +694,7 @@ class_exists($this->name, false) &&
             foreach ($groups as $group) {
                 if (isset($this->groups[$group])) {
                     foreach ($this->groups[$group] as $test) {
-                        $tests->attach($test);
+                        $tests->offsetSet($test, null);
                     }
                 }
             }
diff --git a/PHPUnit/TextUI/TestRunner.php b/PHPUnit/TextUI/TestRunner.php
index d3e273018cd..22f8beb20de 100644
--- a/PHPUnit/TextUI/TestRunner.php
+++ b/PHPUnit/TextUI/TestRunner.php
@@ -86,8 +86,15 @@ class PHPUnit_TextUI_TestRunner extends PHPUnit_Runner_BaseTestRunner
      * @param PHP_CodeCoverage_Filter        $filter
      * @since Method available since Release 3.4.0
      */
-    public function __construct(PHPUnit_Runner_TestSuiteLoader $loader = NULL, PHP_CodeCoverage_Filter $filter = NULL)
+    public function __construct($loader = NULL, $filter = NULL)
     {
+        if ($loader !== NULL && !$loader instanceof PHPUnit_Runner_TestSuiteLoader) {
+            throw PHPUnit_Util_InvalidArgumentHelper::factory(1, 'PHPUnit_Runner_TestSuiteLoader');
+        }
+        if ($filter !== NULL && !$filter instanceof PHP_CodeCoverage_Filter) {
+            throw PHPUnit_Util_InvalidArgumentHelper::factory(2, 'PHP_CodeCoverage_Filter');
+        }
+
         if ($filter === NULL) {
             $filter = new PHP_CodeCoverage_Filter;
         }
diff --git a/PHPUnit/Util/Class.php b/PHPUnit/Util/Class.php
index 765db545c87..ce86ab4ff97 100644
--- a/PHPUnit/Util/Class.php
+++ b/PHPUnit/Util/Class.php
@@ -320,9 +320,12 @@ public static function getObjectAttribute($object, $attributeName)
             if (!$attribute || $attribute->isPublic()) {
                 return $object->$attributeName;
             }
-            $attribute->setAccessible(TRUE);
+            if (PHP_VERSION_ID < 80100) {
+                $attribute->setAccessible(TRUE);
+            }
             $value = $attribute->getValue($object);
-            $attribute->setAccessible(FALSE);
+
+
 
             return $value;
         }
diff --git a/PHPUnit/Util/GlobalState.php b/PHPUnit/Util/GlobalState.php
index 008e691e98c..be18c7ad0b4 100644
--- a/PHPUnit/Util/GlobalState.php
+++ b/PHPUnit/Util/GlobalState.php
@@ -327,7 +327,9 @@ public static function backupStaticAttributes(array $blacklist)
 
                         if (!isset($blacklist[$declaredClasses[$i]]) ||
                            !in_array($name, $blacklist[$declaredClasses[$i]])) {
-                            $attribute->setAccessible(TRUE);
+                            if (PHP_VERSION_ID < 80100) {
+                                $attribute->setAccessible(TRUE);
+                            }
                             $value = $attribute->getValue();
 
                             if (!$value instanceof Closure) {
@@ -349,7 +351,9 @@ public static function restoreStaticAttributes()
         foreach (self::$staticAttributes as $className => $staticAttributes) {
             foreach ($staticAttributes as $name => $value) {
                 $reflector = new ReflectionProperty($className, $name);
-                $reflector->setAccessible(TRUE);
+                if (PHP_VERSION_ID < 80100) {
+                    $reflector->setAccessible(TRUE);
+                }
                 // two-arg form: single-arg setValue() for static properties is deprecated in PHP 8.3
                 $reflector->setValue(null, unserialize($value));
             }
diff --git a/PHPUnit/Util/PHP.php b/PHPUnit/Util/PHP.php
index 27b7f3790f2..a1ffef80faf 100644
--- a/PHPUnit/Util/PHP.php
+++ b/PHPUnit/Util/PHP.php
@@ -159,8 +159,15 @@ public static function factory()
      * @return array|null
      * @throws PHPUnit_Framework_Exception
      */
-    public function runJob($job, PHPUnit_Framework_Test $test = NULL, PHPUnit_Framework_TestResult $result = NULL)
+    public function runJob($job, $test = NULL, $result = NULL)
     {
+        if ($test !== NULL && !$test instanceof PHPUnit_Framework_Test) {
+            throw PHPUnit_Util_InvalidArgumentHelper::factory(2, 'PHPUnit_Framework_Test');
+        }
+        if ($result !== NULL && !$result instanceof PHPUnit_Framework_TestResult) {
+            throw PHPUnit_Util_InvalidArgumentHelper::factory(3, 'PHPUnit_Framework_TestResult');
+        }
+
         $process = proc_open(
           $this->getPhpBinary(),
           array(
diff --git a/PHPUnit/Util/Type.php b/PHPUnit/Util/Type.php
index de7a52048fb..cd63fad7a61 100644
--- a/PHPUnit/Util/Type.php
+++ b/PHPUnit/Util/Type.php
@@ -127,7 +127,7 @@ protected static function recursiveExport(&$value, $indentation, $processed = nu
             return 'false';
         }
 
-        if (is_float($value) && floatval(intval($value)) === $value) {
+        if (is_float($value) && is_finite($value) && floatval(intval($value)) === $value) {
             return "$value.0";
         }
 
diff --git a/PHPUnit/Util/Type/ExportContext.php b/PHPUnit/Util/Type/ExportContext.php
index 5bdca020c89..3e0b4cfa535 100644
--- a/PHPUnit/Util/Type/ExportContext.php
+++ b/PHPUnit/Util/Type/ExportContext.php
@@ -141,8 +141,8 @@ protected function addArray(array &$value)
      */
     protected function addObject($value)
     {
-        if (!$this->objects->contains($value)) {
-            $this->objects->attach($value);
+        if (!$this->objects->offsetExists($value)) {
+            $this->objects->offsetSet($value, null);
         }
 
         return spl_object_hash($value);
@@ -180,7 +180,7 @@ protected function containsArray(array &$value)
      */
     protected function containsObject($value)
     {
-        if ($this->objects->contains($value)) {
+        if ($this->objects->offsetExists($value)) {
             return spl_object_hash($value);
         }
 
diff --git a/Tests/Framework/AssertTest.php b/Tests/Framework/AssertTest.php
index 5517d48fc31..e0bc5369669 100644
--- a/Tests/Framework/AssertTest.php
+++ b/Tests/Framework/AssertTest.php
@@ -101,7 +101,7 @@ public function testAssertSplObjectStorageContainsObject()
         $a = new stdClass;
         $b = new stdClass;
         $c = new SplObjectStorage;
-        $c->attach($a);
+        $c->offsetSet($a);
 
         $this->assertContains($a, $c);
 
@@ -412,7 +412,7 @@ public function testAssertSplObjectStorageNotContainsObject()
         $a = new stdClass;
         $b = new stdClass;
         $c = new SplObjectStorage;
-        $c->attach($a);
+        $c->offsetSet($a);
 
         $this->assertNotContains($b, $c);
 
@@ -633,9 +633,9 @@ protected function notEqualValues()
         $object2 = new SampleClass(16, 23, 42);
         $object3 = new SampleClass( 4,  8, 15);
         $storage1 = new SplObjectStorage;
-        $storage1->attach($object1);
+        $storage1->offsetSet($object1);
         $storage2 = new SplObjectStorage;
-        $storage2->attach($object3); // same content, different object
+        $storage2->offsetSet($object3); // same content, different object
 
         // cannot use $filesDirectory, because neither setUp() nor
         // setUpBeforeClass() are executed before the data providers
@@ -724,9 +724,9 @@ protected function equalValues()
         $object1 = new SampleClass(4, 8, 15);
         $object2 = new SampleClass(4, 8, 15);
         $storage1 = new SplObjectStorage;
-        $storage1->attach($object1);
+        $storage1->offsetSet($object1);
         $storage2 = new SplObjectStorage;
-        $storage2->attach($object1);
+        $storage2->offsetSet($object1);
 
         return array(
             // strings
diff --git a/Tests/Framework/ConstraintTest.php b/Tests/Framework/ConstraintTest.php
index 4d4ec230105..46de9a26bbf 100644
--- a/Tests/Framework/ConstraintTest.php
+++ b/Tests/Framework/ConstraintTest.php
@@ -733,10 +733,10 @@ public function isEqualProvider()
         $d->c = $c;
 
         $storage1 = new SplObjectStorage;
-        $storage1->attach($a);
-        $storage1->attach($b);
+        $storage1->offsetSet($a);
+        $storage1->offsetSet($b);
         $storage2 = new SplObjectStorage;
-        $storage2->attach($b);
+        $storage2->offsetSet($b);
         $storage1hash = spl_object_hash($storage1);
         $storage2hash = spl_object_hash($storage2);
 
@@ -3200,7 +3200,7 @@ public function testConstraintSplObjectStorageContains()
         $storage = new SplObjectStorage;
         $this->assertFalse($constraint->evaluate($storage, '', TRUE));
 
-        $storage->attach($object);
+        $storage->offsetSet($object);
         $this->assertTrue($constraint->evaluate($storage, '', TRUE));
 
         try {
diff --git a/Tests/_files/DoubleTestCase.php b/Tests/_files/DoubleTestCase.php
index 1e8380a1d0d..1c04612e73b 100644
--- a/Tests/_files/DoubleTestCase.php
+++ b/Tests/_files/DoubleTestCase.php
@@ -14,8 +14,12 @@ public function count()
         return 2;
     }
 
-    public function run(PHPUnit_Framework_TestResult $result = NULL)
+    public function run($result = NULL)
     {
+        if ($result !== NULL && !$result instanceof PHPUnit_Framework_TestResult) {
+            throw PHPUnit_Util_InvalidArgumentHelper::factory(1, 'PHPUnit_Framework_TestResult');
+        }
+
         $result->startTest($this);
 
         $this->testCase->runBare();