fix: don't allow invalid class names

src/Exceptions/AfterAllAlreadyExist.php

@@ -19,6 +19,6 @@ final class AfterAllAlreadyExist extends InvalidArgumentException implements Exc
      */
     public function __construct(string $filename)
     {
-        parent::__construct(sprintf('The afterAll already exists in the filename `%s`.', $filename));
+        parent::__construct(sprintf('The afterAll already exists in the filename [%s].', $filename));
     }
 }

src/Exceptions/AfterAllWithinDescribe.php

@@ -19,6 +19,6 @@ final class AfterAllWithinDescribe extends InvalidArgumentException implements E
      */
     public function __construct(string $filename)
     {
-        parent::__construct(sprintf('The afterAll method can not be used within describe functions. Filename `%s`.', $filename));
+        parent::__construct(sprintf('The afterAll method can not be used within describe functions. Filename [%s].', $filename));
     }
 }

src/Exceptions/AfterBeforeTestFunction.php

@@ -19,6 +19,6 @@ final class AfterBeforeTestFunction extends InvalidArgumentException implements
      */
     public function __construct(string $filename)
     {
-        parent::__construct('After method cannot be used with before the [test|it] functions in the filename `['.$filename.']`.');
+        parent::__construct('After method cannot be used with before the [test|it] functions in the filename ['.$filename.'].');
     }
 }

src/Exceptions/BeforeAllAlreadyExist.php

@@ -19,6 +19,6 @@ final class BeforeAllAlreadyExist extends InvalidArgumentException implements Ex
      */
     public function __construct(string $filename)
     {
-        parent::__construct(sprintf('The beforeAll already exists in the filename `%s`.', $filename));
+        parent::__construct(sprintf('The beforeAll already exists in the filename [%s].', $filename));
     }
 }

src/Exceptions/BeforeAllWithinDescribe.php

@@ -19,6 +19,6 @@ final class BeforeAllWithinDescribe extends InvalidArgumentException implements
      */
     public function __construct(string $filename)
     {
-        parent::__construct(sprintf('The beforeAll method can not be used within describe functions. Filename `%s`.', $filename));
+        parent::__construct(sprintf('The beforeAll method can not be used within describe functions. Filename [%s].', $filename));
     }
 }

src/Exceptions/DatasetAlreadyExists.php

@@ -19,6 +19,6 @@ final class DatasetAlreadyExists extends InvalidArgumentException implements Exc
      */
     public function __construct(string $name, string $scope)
     {
-        parent::__construct(sprintf('A dataset with the name `%s` already exists in scope [%s].', $name, $scope));
+        parent::__construct(sprintf('A dataset with the name [%s] already exists in scope [%s].', $name, $scope));
     }
 }

src/Exceptions/DatasetDoesNotExist.php

@@ -19,6 +19,6 @@ final class DatasetDoesNotExist extends InvalidArgumentException implements Exce
      */
     public function __construct(string $name)
     {
-        parent::__construct(sprintf("A dataset with the name `%s` does not exist. You can create it using `dataset('%s', ['a', 'b']);`.", $name, $name));
+        parent::__construct(sprintf("A dataset with the name [%s] does not exist. You can create it using `dataset('%s', ['a', 'b']);`.", $name, $name));
     }
 }

src/Exceptions/FileOrFolderNotFound.php

@@ -19,6 +19,6 @@ final class FileOrFolderNotFound extends InvalidArgumentException implements Exc
      */
     public function __construct(string $filename)
     {
-        parent::__construct(sprintf('The file or folder with the name `%s` could not be found.', $filename));
+        parent::__construct(sprintf('The file or folder with the name [%s] could not be found.', $filename));
     }
 }

src/Exceptions/InvalidTestClassName.php

@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Exceptions;
+
+use InvalidArgumentException;
+use NunoMaduro\Collision\Contracts\RenderlessEditor;
+use NunoMaduro\Collision\Contracts\RenderlessTrace;
+use Symfony\Component\Console\Exception\ExceptionInterface;
+
+/**
+ * @internal
+ */
+final class InvalidTestClassName extends InvalidArgumentException implements ExceptionInterface, RenderlessEditor, RenderlessTrace
+{
+    /**
+     * Creates a new Exception instance for the given class name.
+     */
+    public static function fromClassName(string $filename, string $className): self
+    {
+        return new self(sprintf(
+            'The test file [%s] would create the class [%s], which is not a valid PHP class name. Please rename the test file.',
+            $filename,
+            $className,
+        ));
+    }
+
+    /**
+     * Creates a new Exception instance for the given namespace.
+     */
+    public static function fromNamespace(string $filename, string $namespace, string $part): self
+    {
+        return new self(sprintf(
+            'The test file [%s] would create the namespace [%s], which is not a valid PHP namespace, as [%s] may not be used as a namespace name. Please rename the folder in question.',
+            $filename,
+            $namespace,
+            $part,
+        ));
+    }
+}

src/Exceptions/TestAlreadyExist.php

@@ -19,6 +19,6 @@ final class TestAlreadyExist extends InvalidArgumentException implements Excepti
      */
     public function __construct(string $fileName, string $description)
     {
-        parent::__construct(sprintf('A test with the description `%s` already exists in the filename `%s`.', $description, $fileName));
+        parent::__construct(sprintf('A test with the description [%s] already exists in the filename [%s].', $description, $fileName));
     }
 }

src/Exceptions/TestCaseClassOrTraitNotFound.php

@@ -19,6 +19,6 @@ final class TestCaseClassOrTraitNotFound extends InvalidArgumentException implem
      */
     public function __construct(string $testCaseClass)
     {
-        parent::__construct(sprintf('The class `%s` was not found.', $testCaseClass));
+        parent::__construct(sprintf('The class [%s] was not found.', $testCaseClass));
     }
 }

src/Exceptions/TestDescriptionMissing.php

@@ -19,6 +19,6 @@ final class TestDescriptionMissing extends InvalidArgumentException implements E
      */
     public function __construct(string $fileName)
     {
-        parent::__construct(sprintf('Test description is missing in the filename `%s`.', $fileName));
+        parent::__construct(sprintf('Test description is missing in the filename [%s].', $fileName));
     }
 }

src/Factories/TestCaseFactory.php

@@ -9,6 +9,7 @@ use Pest\Concerns;
 use Pest\Contracts\HasPrintableTestCaseName;
 use Pest\Evaluators\Attributes;
 use Pest\Exceptions\DatasetMissing;
+use Pest\Exceptions\InvalidTestClassName;
 use Pest\Exceptions\ShouldNotHappen;
 use Pest\Exceptions\TestAlreadyExist;
 use Pest\Exceptions\TestClosureMustNotBeStatic;
@@ -138,6 +139,16 @@ final class TestCaseFactory
 
         if (trim($className) === '') {
             $className = 'InvalidTestName'.Str::random();
+        } elseif (! Str::isValidClassName($className)) {
+            throw InvalidTestClassName::fromClassName($this->filename, $className);
+        }
+
+        if ($this->namespace === null) {
+            foreach ($partsFQN as $partFQN) {
+                if (! Str::isValidIdentifier($partFQN)) {
+                    throw InvalidTestClassName::fromNamespace($this->filename, $namespace, $partFQN);
+                }
+            }
         }
 
         $this->attributes = [

src/Support/Str.php

@@ -17,6 +17,33 @@ final class Str
 
     private const string PREFIX = '__pest_evaluable_';
 
+    /**
+     * The list of names PHP reserves, and therefore refuses, as class names.
+     *
+     * @see https://github.com/php/php-src/blob/master/Zend/zend_compile.c
+     *
+     * @var array<int, string>
+     */
+    private const array RESERVED_CLASS_NAMES = [
+        'array',
+        'bool',
+        'callable',
+        'false',
+        'float',
+        'int',
+        'iterable',
+        'mixed',
+        'never',
+        'null',
+        'object',
+        'parent',
+        'self',
+        'static',
+        'string',
+        'true',
+        'void',
+    ];
+
     /**
      * Create a (unsecure & non-cryptographically safe) random alpha-numeric
      * string value.
@@ -64,6 +91,35 @@ final class Str
         return (string) preg_replace('/[^a-zA-Z0-9_\x80-\xff]/', '_', $code);
     }
 
+    /**
+     * Determine if the given name is a valid PHP identifier, and therefore may
+     * be used as a single namespace name.
+     */
+    public static function isValidIdentifier(string $name): bool
+    {
+        return preg_match('/^[a-zA-Z_\x80-\xff][a-zA-Z0-9_\x80-\xff]*$/', $name) === 1;
+    }
+
+    /**
+     * Determine if the given name may be declared as a class name by an `eval`.
+     */
+    public static function isValidClassName(string $name): bool
+    {
+        if (! self::isValidIdentifier($name)) {
+            return false;
+        }
+
+        if (in_array(strtolower($name), self::RESERVED_CLASS_NAMES, true)) {
+            return false;
+        }
+
+        $tokens = token_get_all(sprintf('<?php %s;', $name));
+
+        // Anything the lexer sees as a keyword, like `list` or `match`, may not
+        // be used as a class name.
+        return is_array($tokens[1] ?? null) && $tokens[1][0] === T_STRING;
+    }
+
     /**
      * Get the portion of a string before the last occurrence of a given value.
      */