diff --git a/src/Framework/Constraint/IsEqual.php b/src/Framework/Constraint/IsEqual.php
index d3a00a0fde6..930fd74ece7 100644
--- a/src/Framework/Constraint/IsEqual.php
+++ b/src/Framework/Constraint/IsEqual.php
@@ -117,7 +117,7 @@ public function evaluate($other, $description = '', $returnResult = false)
     /**
      * Returns a string representation of the constraint.
      *
-     * @throws SebastianBergmann\RecursionContext\InvalidArgumentException
+     * @throws \SebastianBergmann\RecursionContext\InvalidArgumentException
      */
     public function toString(): string
     {
diff --git a/src/Framework/Constraint/IsIdentical.php b/src/Framework/Constraint/IsIdentical.php
index 7975966b382..c4362f00887 100644
--- a/src/Framework/Constraint/IsIdentical.php
+++ b/src/Framework/Constraint/IsIdentical.php
@@ -57,7 +57,7 @@ public function __construct($value)
      * @param bool   $returnResult Whether to return a result or throw an exception
      *
      * @throws ExpectationFailedException
-     * @throws SebastianBergmann\RecursionContext\InvalidArgumentException
+     * @throws \SebastianBergmann\RecursionContext\InvalidArgumentException
      */
     public function evaluate($other, $description = '', $returnResult = false)
     {
@@ -103,7 +103,7 @@ public function evaluate($other, $description = '', $returnResult = false)
     /**
      * Returns a string representation of the constraint.
      *
-     * @throws SebastianBergmann\RecursionContext\InvalidArgumentException
+     * @throws \SebastianBergmann\RecursionContext\InvalidArgumentException
      */
     public function toString(): string
     {
@@ -123,7 +123,7 @@ public function toString(): string
      *
      * @param mixed $other evaluated value or object
      *
-     * @throws SebastianBergmann\RecursionContext\InvalidArgumentException
+     * @throws \SebastianBergmann\RecursionContext\InvalidArgumentException
      */
     protected function failureDescription($other): string
     {
diff --git a/src/Runner/TestSuiteSorter.php b/src/Runner/TestSuiteSorter.php
index c19c0e88591..7785701ca89 100644
--- a/src/Runner/TestSuiteSorter.php
+++ b/src/Runner/TestSuiteSorter.php
@@ -203,6 +203,10 @@ function ($left, $right) {
      */
     private function cmpDefectPriorityAndTime(Test $a, Test $b): int
     {
+        if (!$a instanceof TestCase || !$b instanceof TestCase) {
+            return 0;
+        }
+
         $priorityA = $this->defectSortOrder[$a->getName()] ?? 0;
         $priorityB = $this->defectSortOrder[$b->getName()] ?? 0;
 
@@ -224,6 +228,10 @@ private function cmpDefectPriorityAndTime(Test $a, Test $b): int
      */
     private function cmpDuration(Test $a, Test $b): int
     {
+        if (!$a instanceof TestCase || !$b instanceof TestCase) {
+            return 0;
+        }
+
         return $this->cache->getTime($a->getName()) <=> $this->cache->getTime($b->getName());
     }
 
diff --git a/src/TextUI/TestRunner.php b/src/TextUI/TestRunner.php
index 6aa2b9fe119..ebcdb976811 100644
--- a/src/TextUI/TestRunner.php
+++ b/src/TextUI/TestRunner.php
@@ -14,6 +14,7 @@
 use PHPUnit\Framework\Error\Warning;
 use PHPUnit\Framework\Exception;
 use PHPUnit\Framework\Test;
+use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\TestListener;
 use PHPUnit\Framework\TestResult;
 use PHPUnit\Framework\TestSuite;
@@ -161,16 +162,18 @@ public function doRun(Test $suite, array $arguments = [], bool $exit = true): Te
             $GLOBALS['__PHPUNIT_BOOTSTRAP'] = $arguments['bootstrap'];
         }
 
-        if ($arguments['backupGlobals'] === true) {
-            $suite->setBackupGlobals(true);
-        }
+        if ($suite instanceof TestCase || $suite instanceof TestSuite) {
+            if ($arguments['backupGlobals'] === true) {
+                $suite->setBackupGlobals(true);
+            }
 
-        if ($arguments['backupStaticAttributes'] === true) {
-            $suite->setBackupStaticAttributes(true);
-        }
+            if ($arguments['backupStaticAttributes'] === true) {
+                $suite->setBackupStaticAttributes(true);
+            }
 
-        if ($arguments['beStrictAboutChangesToGlobalState'] === true) {
-            $suite->setBeStrictAboutChangesToGlobalState(true);
+            if ($arguments['beStrictAboutChangesToGlobalState'] === true) {
+                $suite->setBeStrictAboutChangesToGlobalState(true);
+            }
         }
 
         if ($arguments['executionOrder'] === TestSuiteSorter::ORDER_RANDOMIZED) {
diff --git a/src/Util/Log/JUnit.php b/src/Util/Log/JUnit.php
index 8154af3e7a3..f81402e4ad4 100644
--- a/src/Util/Log/JUnit.php
+++ b/src/Util/Log/JUnit.php
@@ -287,24 +287,27 @@ public function endTestSuite(TestSuite $suite): void
      * A test started.
      *
      * @throws \SebastianBergmann\RecursionContext\InvalidArgumentException
+     * @throws ReflectionException
      */
     public function startTest(Test $test): void
     {
+        if (!$test instanceof TestCase) {
+            return;
+        }
+
         $testCase = $this->document->createElement('testcase');
         $testCase->setAttribute('name', $test->getName());
 
-        if ($test instanceof TestCase) {
-            $class      = new ReflectionClass($test);
-            $methodName = $test->getName(!$test->usesDataProvider());
+        $class      = new ReflectionClass($test);
+        $methodName = $test->getName(!$test->usesDataProvider());
 
-            if ($class->hasMethod($methodName)) {
-                $method = $class->getMethod($methodName);
+        if ($class->hasMethod($methodName)) {
+            $method = $class->getMethod($methodName);
 
-                $testCase->setAttribute('class', $class->getName());
-                $testCase->setAttribute('classname', \str_replace('\\', '.', $class->getName()));
-                $testCase->setAttribute('file', $class->getFileName());
-                $testCase->setAttribute('line', $method->getStartLine());
-            }
+            $testCase->setAttribute('class', $class->getName());
+            $testCase->setAttribute('classname', \str_replace('\\', '.', $class->getName()));
+            $testCase->setAttribute('file', $class->getFileName());
+            $testCase->setAttribute('line', $method->getStartLine());
         }
 
         $this->currentTestCase = $testCase;
@@ -315,16 +318,18 @@ public function startTest(Test $test): void
      */
     public function endTest(Test $test, float $time): void
     {
-        if ($test instanceof TestCase) {
-            $numAssertions = $test->getNumAssertions();
-            $this->testSuiteAssertions[$this->testSuiteLevel] += $numAssertions;
-
-            $this->currentTestCase->setAttribute(
-                'assertions',
-                $numAssertions
-            );
+        if (!$test instanceof TestCase) {
+            return;
         }
 
+        $numAssertions = $test->getNumAssertions();
+        $this->testSuiteAssertions[$this->testSuiteLevel] += $numAssertions;
+
+        $this->currentTestCase->setAttribute(
+            'assertions',
+            $numAssertions
+        );
+
         $this->currentTestCase->setAttribute(
             'time',
             \sprintf('%F', $time)
@@ -337,7 +342,7 @@ public function endTest(Test $test, float $time): void
         $this->testSuiteTests[$this->testSuiteLevel]++;
         $this->testSuiteTimes[$this->testSuiteLevel] += $time;
 
-        if (\method_exists($test, 'hasOutput') && $test->hasOutput()) {
+        if ($test->hasOutput()) {
             $systemOut = $this->document->createElement(
                 'system-out',
                 Xml::prepareString($test->getActualOutput())
diff --git a/src/Util/Log/TeamCity.php b/src/Util/Log/TeamCity.php
index 4e8f446c4d4..a6c27b8a980 100644
--- a/src/Util/Log/TeamCity.php
+++ b/src/Util/Log/TeamCity.php
@@ -57,6 +57,10 @@ public function printResult(TestResult $result): void
      */
     public function addError(Test $test, \Throwable $t, float $time): void
     {
+        if (!$test instanceof TestCase) {
+            return;
+        }
+
         $this->printEvent(
             'testFailed',
             [
@@ -75,6 +79,10 @@ public function addError(Test $test, \Throwable $t, float $time): void
      */
     public function addWarning(Test $test, Warning $e, float $time): void
     {
+        if (!$test instanceof TestCase) {
+            return;
+        }
+
         $this->printEvent(
             'testFailed',
             [
@@ -93,6 +101,10 @@ public function addWarning(Test $test, Warning $e, float $time): void
      */
     public function addFailure(Test $test, AssertionFailedError $e, float $time): void
     {
+        if (!$test instanceof TestCase) {
+            return;
+        }
+
         $parameters = [
             'name'     => $test->getName(),
             'message'  => self::getMessage($e),
@@ -132,6 +144,10 @@ public function addFailure(Test $test, AssertionFailedError $e, float $time): vo
      */
     public function addIncompleteTest(Test $test, \Throwable $t, float $time): void
     {
+        if (!$test instanceof TestCase) {
+            return;
+        }
+
         $this->printIgnoredTest($test->getName(), $t, $time);
     }
 
@@ -142,6 +158,10 @@ public function addIncompleteTest(Test $test, \Throwable $t, float $time): void
      */
     public function addRiskyTest(Test $test, \Throwable $t, float $time): void
     {
+        if (!$test instanceof TestCase) {
+            return;
+        }
+
         $this->addError($test, $t, $time);
     }
 
@@ -152,6 +172,10 @@ public function addRiskyTest(Test $test, \Throwable $t, float $time): void
      */
     public function addSkippedTest(Test $test, \Throwable $t, float $time): void
     {
+        if (!$test instanceof TestCase) {
+            return;
+        }
+
         $testName = $test->getName();
 
         if ($this->startedTestName !== $testName) {
@@ -253,6 +277,10 @@ public function endTestSuite(TestSuite $suite): void
      */
     public function startTest(Test $test): void
     {
+        if (!$test instanceof TestCase) {
+            return;
+        }
+
         $testName              = $test->getName();
         $this->startedTestName = $testName;
         $params                = ['name' => $testName];
@@ -271,6 +299,10 @@ public function startTest(Test $test): void
      */
     public function endTest(Test $test, float $time): void
     {
+        if (!$test instanceof TestCase) {
+            return;
+        }
+
         parent::endTest($test, $time);
 
         $this->printEvent(