[Debug] fix ClassNotFoundFatalErrorHandler

This PR was squashed before being merged into the 3.4 branch (closes #32800).

Discussion
----------

Improve some URLs

| Q             | A
| ------------- | ---
| Branch?       | 3.4 <!-- see below -->
| Bug fix?      | no
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | N/A   <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | N/A <!-- required for new features -->

<!--
Replace this notice by a short README for your feature/bugfix. This will help people
understand your PR and can be used as a start for the documentation.

Additionally (see https://symfony.com/roadmap):
 - Bug fixes must be submitted against the lowest maintained branch where they apply
   (lowest branches are regularly merged to upper ones so they get the fixes too).
 - Features and deprecations must be submitted against branch 4.4.
 - Legacy code removals go to the master branch.
-->

Commits
-------

fab17a4487 Improve some URLs

DebugClassLoader.php

@@ -317,6 +317,12 @@ class DebugClassLoader
         return $deprecations;
     }
 
+    /**
+     * @param string $file
+     * @param string $class
+     *
+     * @return array|null
+     */
     public function checkCase(\ReflectionClass $refl, $file, $class)
     {
         $real = explode('\\', $class.strrchr($file, '.'));
@@ -333,7 +339,7 @@ class DebugClassLoader
         array_splice($tail, 0, $i + 1);
 
         if (!$tail) {
-            return;
+            return null;
         }
 
         $tail = \DIRECTORY_SEPARATOR.implode(\DIRECTORY_SEPARATOR, $tail);
@@ -349,6 +355,8 @@ class DebugClassLoader
         ) {
             return [substr($tail, -$tailLen + 1), substr($real, -$tailLen + 1), substr($real, 0, -$tailLen + 1)];
         }
+
+        return null;
     }
 
     /**
@@ -396,7 +404,7 @@ class DebugClassLoader
         }
 
         if (isset($dirFiles[$file])) {
-            return $real .= $dirFiles[$file];
+            return $real.$dirFiles[$file];
         }
 
         $kFile = strtolower($file);
@@ -415,7 +423,7 @@ class DebugClassLoader
             self::$darwinCache[$kDir][1] = $dirFiles;
         }
 
-        return $real .= $dirFiles[$kFile];
+        return $real.$dirFiles[$kFile];
     }
 
     /**

ErrorHandler.php

@@ -382,8 +382,7 @@ class ErrorHandler
      */
     public function handleError($type, $message, $file, $line)
     {
-        // @deprecated to be removed in Symfony 5.0
-        if (\PHP_VERSION_ID >= 70300 && $message && '"' === $message[0] && 0 === strpos($message, '"continue') && preg_match('/^"continue(?: \d++)?" targeting switch is equivalent to "break(?: \d++)?"\. Did you mean to use "continue(?: \d++)?"\?$/', $message)) {
+        if (\PHP_VERSION_ID >= 70300 && E_WARNING === $type && '"' === $message[0] && false !== strpos($message, '" targeting switch is equivalent to "break')) {
             $type = E_DEPRECATED;
         }
 
@@ -450,7 +449,7 @@ class ErrorHandler
                 self::$silencedErrorCache[$id][$message] = $errorAsException;
             }
             if (null === $lightTrace) {
-                return;
+                return true;
             }
         } else {
             if ($scope) {
@@ -470,7 +469,7 @@ class ErrorHandler
         }
 
         if ($throw) {
-            if (E_USER_ERROR & $type) {
+            if (\PHP_VERSION_ID < 70400 && E_USER_ERROR & $type) {
                 for ($i = 1; isset($backtrace[$i]); ++$i) {
                     if (isset($backtrace[$i]['function'], $backtrace[$i]['type'], $backtrace[$i - 1]['function'])
                         && '__toString' === $backtrace[$i]['function']
@@ -599,7 +598,9 @@ class ErrorHandler
         $this->exceptionHandler = null;
         try {
             if (null !== $exceptionHandler) {
-                return \call_user_func($exceptionHandler, $exception);
+                $exceptionHandler($exception);
+
+                return;
             }
             $handlerException = $handlerException ?: $exception;
         } catch (\Exception $handlerException) {

Exception/SilencedErrorContext.php

@@ -54,7 +54,7 @@ class SilencedErrorContext implements \JsonSerializable
         return $this->trace;
     }
 
-    public function JsonSerialize()
+    public function jsonSerialize()
     {
         return [
             'severity' => $this->severity,

FatalErrorHandler/ClassNotFoundFatalErrorHandler.php

@@ -33,11 +33,11 @@ class ClassNotFoundFatalErrorHandler implements FatalErrorHandlerInterface
         $notFoundSuffix = '\' not found';
         $notFoundSuffixLen = \strlen($notFoundSuffix);
         if ($notFoundSuffixLen > $messageLen) {
-            return;
+            return null;
         }
 
         if (0 !== substr_compare($error['message'], $notFoundSuffix, -$notFoundSuffixLen)) {
-            return;
+            return null;
         }
 
         foreach (['class', 'interface', 'trait'] as $typeName) {
@@ -71,6 +71,8 @@ class ClassNotFoundFatalErrorHandler implements FatalErrorHandlerInterface
 
             return new ClassNotFoundException($message, $exception);
         }
+
+        return null;
     }
 
     /**
@@ -196,6 +198,8 @@ class ClassNotFoundFatalErrorHandler implements FatalErrorHandlerInterface
                 return $candidate;
             }
         }
+
+        return null;
     }
 
     /**

FatalErrorHandler/UndefinedFunctionFatalErrorHandler.php

@@ -30,17 +30,17 @@ class UndefinedFunctionFatalErrorHandler implements FatalErrorHandlerInterface
         $notFoundSuffix = '()';
         $notFoundSuffixLen = \strlen($notFoundSuffix);
         if ($notFoundSuffixLen > $messageLen) {
-            return;
+            return null;
         }
 
         if (0 !== substr_compare($error['message'], $notFoundSuffix, -$notFoundSuffixLen)) {
-            return;
+            return null;
         }
 
         $prefix = 'Call to undefined function ';
         $prefixLen = \strlen($prefix);
         if (0 !== strpos($error['message'], $prefix)) {
-            return;
+            return null;
         }
 
         $fullyQualifiedFunctionName = substr($error['message'], $prefixLen, -$notFoundSuffixLen);

FatalErrorHandler/UndefinedMethodFatalErrorHandler.php

@@ -28,7 +28,7 @@ class UndefinedMethodFatalErrorHandler implements FatalErrorHandlerInterface
     {
         preg_match('/^Call to undefined method (.*)::(.*)\(\)$/', $error['message'], $matches);
         if (!$matches) {
-            return;
+            return null;
         }
 
         $className = $matches[1];

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2004-2019 Fabien Potencier
+Copyright (c) 2004-2020 Fabien Potencier
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -6,7 +6,7 @@ The Debug component provides tools to ease debugging PHP code.
 Resources
 ---------
 
-  * [Documentation](https://symfony.com/doc/current/components/debug/index.html)
+  * [Documentation](https://symfony.com/doc/current/components/debug.html)
   * [Contributing](https://symfony.com/doc/current/contributing/index.html)
   * [Report issues](https://github.com/symfony/symfony/issues) and
     [send Pull Requests](https://github.com/symfony/symfony/pulls)

Tests/DebugClassLoaderTest.php

@@ -59,21 +59,19 @@ class DebugClassLoaderTest extends TestCase
         $this->fail('DebugClassLoader did not register');
     }
 
-    /**
-     * @expectedException \Exception
-     * @expectedExceptionMessage boo
-     */
     public function testThrowingClass()
     {
+        $this->expectException('Exception');
+        $this->expectExceptionMessage('boo');
         try {
-            class_exists(__NAMESPACE__.'\Fixtures\Throwing');
+            class_exists(Fixtures\Throwing::class);
             $this->fail('Exception expected');
         } catch (\Exception $e) {
             $this->assertSame('boo', $e->getMessage());
         }
 
         // the second call also should throw
-        class_exists(__NAMESPACE__.'\Fixtures\Throwing');
+        class_exists(Fixtures\Throwing::class);
     }
 
     public function testUnsilencing()
@@ -92,7 +90,7 @@ class DebugClassLoaderTest extends TestCase
 
         // See below: this will fail with parse error
         // but this should not be @-silenced.
-        @class_exists(__NAMESPACE__.'\TestingUnsilencing', true);
+        @class_exists(TestingUnsilencing::class, true);
 
         $output = ob_get_clean();
 
@@ -139,34 +137,28 @@ class DebugClassLoaderTest extends TestCase
         }
     }
 
-    /**
-     * @expectedException \RuntimeException
-     * @expectedExceptionMessage Case mismatch between loaded and declared class names
-     */
     public function testNameCaseMismatch()
     {
-        class_exists(__NAMESPACE__.'\TestingCaseMismatch', true);
+        $this->expectException('RuntimeException');
+        $this->expectExceptionMessage('Case mismatch between loaded and declared class names');
+        class_exists(TestingCaseMismatch::class, true);
     }
 
-    /**
-     * @expectedException \RuntimeException
-     * @expectedExceptionMessage Case mismatch between class and real file names
-     */
     public function testFileCaseMismatch()
     {
+        $this->expectException('RuntimeException');
+        $this->expectExceptionMessage('Case mismatch between class and real file names');
         if (!file_exists(__DIR__.'/Fixtures/CaseMismatch.php')) {
             $this->markTestSkipped('Can only be run on case insensitive filesystems');
         }
 
-        class_exists(__NAMESPACE__.'\Fixtures\CaseMismatch', true);
+        class_exists(Fixtures\CaseMismatch::class, true);
     }
 
-    /**
-     * @expectedException \RuntimeException
-     * @expectedExceptionMessage Case mismatch between loaded and declared class names
-     */
     public function testPsr4CaseMismatch()
     {
+        $this->expectException('RuntimeException');
+        $this->expectExceptionMessage('Case mismatch between loaded and declared class names');
         class_exists(__NAMESPACE__.'\Fixtures\Psr4CaseMismatch', true);
     }
 
@@ -182,7 +174,7 @@ class DebugClassLoaderTest extends TestCase
 
     public function testClassAlias()
     {
-        $this->assertTrue(class_exists(__NAMESPACE__.'\Fixtures\ClassAlias', true));
+        $this->assertTrue(class_exists(Fixtures\ClassAlias::class, true));
     }
 
     /**
@@ -224,7 +216,7 @@ class DebugClassLoaderTest extends TestCase
         $e = error_reporting(0);
         trigger_error('', E_USER_NOTICE);
 
-        class_exists('Test\\'.__NAMESPACE__.'\\NonDeprecatedInterfaceClass', true);
+        class_exists('Test\\'.NonDeprecatedInterfaceClass::class, true);
 
         error_reporting($e);
         restore_error_handler();
@@ -272,7 +264,7 @@ class DebugClassLoaderTest extends TestCase
         $e = error_reporting(0);
         trigger_error('', E_USER_NOTICE);
 
-        class_exists('Test\\'.__NAMESPACE__.'\\Float', true);
+        class_exists('Test\\'.Float::class, true);
 
         error_reporting($e);
         restore_error_handler();
@@ -297,7 +289,7 @@ class DebugClassLoaderTest extends TestCase
         require __DIR__.'/Fixtures/FinalClasses.php';
 
         $i = 1;
-        while (class_exists($finalClass = __NAMESPACE__.'\\Fixtures\\FinalClass'.$i++, false)) {
+        while (class_exists($finalClass = Fixtures\FinalClass::class.$i++, false)) {
             spl_autoload_call($finalClass);
             class_exists('Test\\'.__NAMESPACE__.'\\Extends'.substr($finalClass, strrpos($finalClass, '\\') + 1), true);
         }
@@ -323,7 +315,7 @@ class DebugClassLoaderTest extends TestCase
         set_error_handler(function ($type, $msg) use (&$deprecations) { $deprecations[] = $msg; });
         $e = error_reporting(E_USER_DEPRECATED);
 
-        class_exists(__NAMESPACE__.'\\Fixtures\\ExtendedFinalMethod', true);
+        class_exists(Fixtures\ExtendedFinalMethod::class, true);
 
         error_reporting($e);
         restore_error_handler();
@@ -342,7 +334,7 @@ class DebugClassLoaderTest extends TestCase
         $e = error_reporting(0);
         trigger_error('', E_USER_NOTICE);
 
-        class_exists('Test\\'.__NAMESPACE__.'\\ExtendsAnnotatedClass', true);
+        class_exists('Test\\'.ExtendsAnnotatedClass::class, true);
 
         error_reporting($e);
         restore_error_handler();
@@ -359,7 +351,7 @@ class DebugClassLoaderTest extends TestCase
         set_error_handler(function ($type, $msg) use (&$deprecations) { $deprecations[] = $msg; });
         $e = error_reporting(E_USER_DEPRECATED);
 
-        class_exists('Test\\'.__NAMESPACE__.'\\ExtendsInternals', true);
+        class_exists('Test\\'.ExtendsInternals::class, true);
 
         error_reporting($e);
         restore_error_handler();
@@ -378,7 +370,7 @@ class DebugClassLoaderTest extends TestCase
         set_error_handler(function ($type, $msg) use (&$deprecations) { $deprecations[] = $msg; });
         $e = error_reporting(E_USER_DEPRECATED);
 
-        class_exists('Test\\'.__NAMESPACE__.'\\UseTraitWithInternalMethod', true);
+        class_exists('Test\\'.UseTraitWithInternalMethod::class, true);
 
         error_reporting($e);
         restore_error_handler();
@@ -388,7 +380,7 @@ class DebugClassLoaderTest extends TestCase
 
     public function testEvaluatedCode()
     {
-        $this->assertTrue(class_exists(__NAMESPACE__.'\Fixtures\DefinitionInEvaluatedCode', true));
+        $this->assertTrue(class_exists(Fixtures\DefinitionInEvaluatedCode::class, true));
     }
 }
 
@@ -407,11 +399,11 @@ class ClassLoader
     {
         $fixtureDir = __DIR__.\DIRECTORY_SEPARATOR.'Fixtures'.\DIRECTORY_SEPARATOR;
 
-        if (__NAMESPACE__.'\TestingUnsilencing' === $class) {
+        if (TestingUnsilencing::class === $class) {
             eval('-- parse error --');
-        } elseif (__NAMESPACE__.'\TestingStacking' === $class) {
+        } elseif (TestingStacking::class === $class) {
             eval('namespace '.__NAMESPACE__.'; class TestingStacking { function foo() {} }');
-        } elseif (__NAMESPACE__.'\TestingCaseMismatch' === $class) {
+        } elseif (TestingCaseMismatch::class === $class) {
             eval('namespace '.__NAMESPACE__.'; class TestingCaseMisMatch {}');
         } elseif (__NAMESPACE__.'\Fixtures\Psr4CaseMismatch' === $class) {
             return $fixtureDir.'psr4'.\DIRECTORY_SEPARATOR.'Psr4CaseMismatch.php';
@@ -421,31 +413,33 @@ class ClassLoader
             return $fixtureDir.'notPsr0Bis.php';
         } elseif ('Symfony\Bridge\Debug\Tests\Fixtures\ExtendsDeprecatedParent' === $class) {
             eval('namespace Symfony\Bridge\Debug\Tests\Fixtures; class ExtendsDeprecatedParent extends \\'.__NAMESPACE__.'\Fixtures\DeprecatedClass {}');
-        } elseif ('Test\\'.__NAMESPACE__.'\DeprecatedParentClass' === $class) {
+        } elseif ('Test\\'.DeprecatedParentClass::class === $class) {
             eval('namespace Test\\'.__NAMESPACE__.'; class DeprecatedParentClass extends \\'.__NAMESPACE__.'\Fixtures\DeprecatedClass {}');
-        } elseif ('Test\\'.__NAMESPACE__.'\DeprecatedInterfaceClass' === $class) {
+        } elseif ('Test\\'.DeprecatedInterfaceClass::class === $class) {
             eval('namespace Test\\'.__NAMESPACE__.'; class DeprecatedInterfaceClass implements \\'.__NAMESPACE__.'\Fixtures\DeprecatedInterface {}');
-        } elseif ('Test\\'.__NAMESPACE__.'\NonDeprecatedInterfaceClass' === $class) {
+        } elseif ('Test\\'.NonDeprecatedInterfaceClass::class === $class) {
             eval('namespace Test\\'.__NAMESPACE__.'; class NonDeprecatedInterfaceClass implements \\'.__NAMESPACE__.'\Fixtures\NonDeprecatedInterface {}');
-        } elseif ('Test\\'.__NAMESPACE__.'\Float' === $class) {
+        } elseif ('Test\\'.Float::class === $class) {
             eval('namespace Test\\'.__NAMESPACE__.'; class Float {}');
-        } elseif (0 === strpos($class, 'Test\\'.__NAMESPACE__.'\ExtendsFinalClass')) {
+        } elseif (0 === strpos($class, 'Test\\'.ExtendsFinalClass::class)) {
             $classShortName = substr($class, strrpos($class, '\\') + 1);
             eval('namespace Test\\'.__NAMESPACE__.'; class '.$classShortName.' extends \\'.__NAMESPACE__.'\Fixtures\\'.substr($classShortName, 7).' {}');
-        } elseif ('Test\\'.__NAMESPACE__.'\ExtendsAnnotatedClass' === $class) {
+        } elseif ('Test\\'.ExtendsAnnotatedClass::class === $class) {
             eval('namespace Test\\'.__NAMESPACE__.'; class ExtendsAnnotatedClass extends \\'.__NAMESPACE__.'\Fixtures\AnnotatedClass {
                 public function deprecatedMethod() { }
             }');
-        } elseif ('Test\\'.__NAMESPACE__.'\ExtendsInternals' === $class) {
+        } elseif ('Test\\'.ExtendsInternals::class === $class) {
             eval('namespace Test\\'.__NAMESPACE__.'; class ExtendsInternals extends ExtendsInternalsParent {
                 use \\'.__NAMESPACE__.'\Fixtures\InternalTrait;
 
                 public function internalMethod() { }
             }');
-        } elseif ('Test\\'.__NAMESPACE__.'\ExtendsInternalsParent' === $class) {
+        } elseif ('Test\\'.ExtendsInternalsParent::class === $class) {
             eval('namespace Test\\'.__NAMESPACE__.'; class ExtendsInternalsParent extends \\'.__NAMESPACE__.'\Fixtures\InternalClass implements \\'.__NAMESPACE__.'\Fixtures\InternalInterface { }');
-        } elseif ('Test\\'.__NAMESPACE__.'\UseTraitWithInternalMethod' === $class) {
+        } elseif ('Test\\'.UseTraitWithInternalMethod::class === $class) {
             eval('namespace Test\\'.__NAMESPACE__.'; class UseTraitWithInternalMethod { use \\'.__NAMESPACE__.'\Fixtures\TraitWithInternalMethod; }');
         }
+
+        return null;
     }
 }

Tests/ErrorHandlerTest.php

@@ -283,6 +283,10 @@ class ErrorHandlerTest extends TestCase
 
     public function testHandleUserError()
     {
+        if (\PHP_VERSION_ID >= 70400) {
+            $this->markTestSkipped('PHP 7.4 allows __toString to throw exceptions');
+        }
+
         try {
             $handler = ErrorHandler::register();
             $handler->throwAt(0, true);
@@ -573,11 +577,11 @@ class ErrorHandlerTest extends TestCase
     }
 
     /**
-     * @expectedException \Exception
      * @group no-hhvm
      */
     public function testCustomExceptionHandler()
     {
+        $this->expectException('Exception');
         $handler = new ErrorHandler();
         $handler->setExceptionHandler(function ($e) use ($handler) {
             $handler->handleException($e);

Tests/Exception/FlattenExceptionTest.php

@@ -199,6 +199,10 @@ class FlattenExceptionTest extends TestCase
 
     public function testArguments()
     {
+        if (\PHP_VERSION_ID >= 70400) {
+            $this->markTestSkipped('PHP 7.4 removes arguments from exception traces.');
+        }
+
         $dh = opendir(__DIR__);
         $fh = tmpfile();
 
@@ -256,22 +260,30 @@ class FlattenExceptionTest extends TestCase
 
         // assertEquals() does not like NAN values.
         $this->assertEquals($array[$i][0], 'float');
-        $this->assertTrue(is_nan($array[$i++][1]));
+        $this->assertNan($array[$i][1]);
     }
 
     public function testRecursionInArguments()
     {
+        if (\PHP_VERSION_ID >= 70400) {
+            $this->markTestSkipped('PHP 7.4 removes arguments from exception traces.');
+        }
+
         $a = null;
         $a = ['foo', [2, &$a]];
         $exception = $this->createException($a);
 
         $flattened = FlattenException::create($exception);
         $trace = $flattened->getTrace();
-        $this->assertContains('*DEEP NESTED ARRAY*', serialize($trace));
+        $this->assertStringContainsString('*DEEP NESTED ARRAY*', serialize($trace));
     }
 
     public function testTooBigArray()
     {
+        if (\PHP_VERSION_ID >= 70400) {
+            $this->markTestSkipped('PHP 7.4 removes arguments from exception traces.');
+        }
+
         $a = [];
         for ($i = 0; $i < 20; ++$i) {
             for ($j = 0; $j < 50; ++$j) {
@@ -291,8 +303,8 @@ class FlattenExceptionTest extends TestCase
 
         $serializeTrace = serialize($trace);
 
-        $this->assertContains('*SKIPPED over 10000 entries*', $serializeTrace);
-        $this->assertNotContains('*value1*', $serializeTrace);
+        $this->assertStringContainsString('*SKIPPED over 10000 entries*', $serializeTrace);
+        $this->assertStringNotContainsString('*value1*', $serializeTrace);
     }
 
     private function createException($foo)

Tests/ExceptionHandlerTest.php

@@ -39,8 +39,8 @@ class ExceptionHandlerTest extends TestCase
         $handler->sendPhpResponse(new \RuntimeException('Foo'));
         $response = ob_get_clean();
 
-        $this->assertContains('Whoops, looks like something went wrong.', $response);
-        $this->assertNotContains('<div class="trace trace-as-html">', $response);
+        $this->assertStringContainsString('Whoops, looks like something went wrong.', $response);
+        $this->assertStringNotContainsString('<div class="trace trace-as-html">', $response);
 
         $handler = new ExceptionHandler(true);
 
@@ -48,8 +48,8 @@ class ExceptionHandlerTest extends TestCase
         $handler->sendPhpResponse(new \RuntimeException('Foo'));
         $response = ob_get_clean();
 
-        $this->assertContains('Whoops, looks like something went wrong.', $response);
-        $this->assertContains('<div class="trace trace-as-html">', $response);
+        $this->assertStringContainsString('Whoops, looks like something went wrong.', $response);
+        $this->assertStringContainsString('<div class="trace trace-as-html">', $response);
     }
 
     public function testStatusCode()
@@ -60,7 +60,7 @@ class ExceptionHandlerTest extends TestCase
         $handler->sendPhpResponse(new NotFoundHttpException('Foo'));
         $response = ob_get_clean();
 
-        $this->assertContains('Sorry, the page you are looking for could not be found.', $response);
+        $this->assertStringContainsString('Sorry, the page you are looking for could not be found.', $response);
 
         $expectedHeaders = [
             ['HTTP/1.0 404', true, null],
@@ -116,7 +116,7 @@ class ExceptionHandlerTest extends TestCase
         });
 
         $handler->handle(new \Exception());
-        ob_end_flush(); // Necessary because of this PHP bug : https://bugs.php.net/bug.php?id=76563
+        ob_end_flush(); // Necessary because of this PHP bug : https://bugs.php.net/76563
         $this->assertSame('ccc', ob_get_clean());
     }
 
@@ -157,7 +157,7 @@ class ExceptionHandlerTest extends TestCase
 
     private function assertThatTheExceptionWasOutput($content, $expectedClass, $expectedTitle, $expectedMessage)
     {
-        $this->assertContains(sprintf('<span class="exception_title"><abbr title="%s">%s</abbr></span>', $expectedClass, $expectedTitle), $content);
-        $this->assertContains(sprintf('<p class="break-long-words trace-message">%s</p>', $expectedMessage), $content);
+        $this->assertStringContainsString(sprintf('<span class="exception_title"><abbr title="%s">%s</abbr></span>', $expectedClass, $expectedTitle), $content);
+        $this->assertStringContainsString(sprintf('<p class="break-long-words trace-message">%s</p>', $expectedMessage), $content);
     }
 }

Tests/FatalErrorHandler/ClassNotFoundFatalErrorHandlerTest.php

@@ -29,6 +29,10 @@ class ClassNotFoundFatalErrorHandlerTest extends TestCase
             // get class loaders wrapped by DebugClassLoader
             if ($function[0] instanceof DebugClassLoader) {
                 $function = $function[0]->getClassLoader();
+
+                if (!\is_array($function)) {
+                    continue;
+                }
             }
 
             if ($function[0] instanceof ComposerClassLoader) {