diff --git a/src/Factories/TestCaseFactory.php b/src/Factories/TestCaseFactory.php
index f3fdf031..4d628e5a 100644
--- a/src/Factories/TestCaseFactory.php
+++ b/src/Factories/TestCaseFactory.php
@@ -5,14 +5,17 @@ declare(strict_types=1);
 namespace Pest\Factories;
 
 use Closure;
+use ParseError;
 use Pest\Concerns;
 use Pest\Contracts\HasPrintableTestCaseName;
 use Pest\Datasets;
 use Pest\Exceptions\ShouldNotHappen;
 use Pest\Support\HigherOrderMessageCollection;
 use Pest\Support\NullClosure;
+use Pest\Support\Str;
 use Pest\TestSuite;
 use PHPUnit\Framework\TestCase;
+use RuntimeException;
 
 /**
  * @internal
@@ -168,7 +171,7 @@ final class TestCaseFactory
             }, $filename);
         }
 
-        $filename     = (string) realpath($filename);
+        $filename     = str_replace('\\\\', '\\', addslashes((string) realpath($filename)));
         $rootPath     = TestSuite::getInstance()->rootPath;
         $relativePath = str_replace($rootPath . DIRECTORY_SEPARATOR, '', $filename);
         $relativePath = dirname(ucfirst($relativePath)) . DIRECTORY_SEPARATOR . basename($relativePath, '.php');
@@ -176,8 +179,12 @@ final class TestCaseFactory
 
         // Strip out any %-encoded octets.
         $relativePath = (string) preg_replace('|%[a-fA-F0-9][a-fA-F0-9]|', '', $relativePath);
+        // Remove escaped quote sequences (maintain namespace)
+        $relativePath = str_replace(array_map(function (string $quote): string {
+            return sprintf('\\%s', $quote);
+        }, ['\'', '"']), '', $relativePath);
         // Limit to A-Z, a-z, 0-9, '_', '-'.
-        $relativePath = (string) preg_replace('/[^A-Za-z0-9.\\\]/', '', $relativePath);
+        $relativePath = (string) preg_replace('/[^A-Za-z0-9\\\\]/', '', $relativePath);
 
         $classFQN = 'P\\' . $relativePath;
         if (class_exists($classFQN)) {
@@ -194,15 +201,24 @@ final class TestCaseFactory
         $namespace = implode('\\', $partsFQN);
         $baseClass = sprintf('\%s', $this->class);
 
-        eval("
-            namespace $namespace;
+        if ('' === trim($className)) {
+            $className = 'InvalidTestName' . Str::random();
+            $classFQN .= $className;
+        }
 
-            final class $className extends $baseClass implements $hasPrintableTestCaseClassFQN {
-                $traitsCode
+        try {
+            eval("
+                namespace $namespace;
 
-                private static \$__filename = '$filename';
-            }
-        ");
+                final class $className extends $baseClass implements $hasPrintableTestCaseClassFQN {
+                    $traitsCode
+
+                    private static \$__filename = '$filename';
+                }
+            ");
+        } catch (ParseError $caught) {
+            throw new RuntimeException(sprintf('Unable to create test case for test file at %s', $filename), 1, $caught);
+        }
 
         return $classFQN;
     }
diff --git a/src/Support/Str.php b/src/Support/Str.php
index aa135647..7a07a105 100644
--- a/src/Support/Str.php
+++ b/src/Support/Str.php
@@ -9,6 +9,25 @@ namespace Pest\Support;
  */
 final class Str
 {
+    /**
+     * Pool of alpha-numeric characters for generating (unsafe) random strings
+     * from.
+     */
+    private const POOL = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
+
+    /**
+     * Create a (unsecure & non-cryptographically safe) random alpha-numeric
+     * string value.
+     *
+     * @param int $length the length of the resulting randomized string
+     *
+     * @see https://github.com/laravel/framework/blob/4.2/src/Illuminate/Support/Str.php#L240-L242
+     */
+    public static function random(int $length = 16): string
+    {
+        return substr(str_shuffle(str_repeat(self::POOL, 5)), 0, $length);
+    }
+
     /**
      * Checks if the given `$target` starts with the given `$search`.
      */
diff --git a/tests/.snapshots/success.txt b/tests/.snapshots/success.txt
index 36136f81..f4db6877 100644
--- a/tests/.snapshots/success.txt
+++ b/tests/.snapshots/success.txt
@@ -103,6 +103,27 @@
    PASS  Tests\Fixtures\ExampleTest
   ✓ it example 2
 
+   PASS  Tests\PHPUnit\CustomAffixes\InvalidTestName
+  ✓ it runs file names like `@#$%^&()-_=+.php`
+
+   PASS  Tests\PHPUnit\CustomAffixes\ATestWithSpaces
+  ✓ it runs file names like `A Test With Spaces.php`
+
+   PASS  Tests\PHPUnit\CustomAffixes\AdditionalFileExtensionspec
+  ✓ it runs file names like `AdditionalFileExtension.spec.php`
+
+   PASS  Tests\PHPUnit\CustomAffixes\ManyExtensionsclasstest
+  ✓ it runs file names like `ManyExtensions.class.test.php`
+
+   PASS  Tests\PHPUnit\CustomAffixes\TestCaseWithQuotes
+  ✓ it runs file names like `Test 'Case' With Quotes.php`
+
+   PASS  Tests\PHPUnit\CustomAffixes\kebabcasespec
+  ✓ it runs file names like `kebab-case-spec.php`
+
+   PASS  Tests\PHPUnit\CustomAffixes\snakecasespec
+  ✓ it runs file names like `snake_case_spec.php`
+
    PASS  Tests\PHPUnit\CustomTestCase\UsesPerDirectory
   ✓ closure was bound to CustomTestCase
 
@@ -188,5 +209,5 @@
   ✓ it is a test
   ✓ it uses correct parent class
 
-  Tests:  7 skipped, 108 passed
+  Tests:  7 skipped, 115 passed
   
\ No newline at end of file
diff --git a/tests/PHPUnit/CustomAffixes/@#$%^&()-_=+.php b/tests/PHPUnit/CustomAffixes/@#$%^&()-_=+.php
new file mode 100644
index 00000000..c829124d
--- /dev/null
+++ b/tests/PHPUnit/CustomAffixes/@#$%^&()-_=+.php
@@ -0,0 +1,10 @@
+<?php
+
+/*
+ * NOTE: To preserve cross-platform testing compatibility we cannot use ! * and
+ * other Windows reserved characters in this test's filename.
+ *
+ * See https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file#naming-conventions
+ */
+
+it(sprintf('runs file names like `%s`', basename(__FILE__)))->assertTrue(true);
diff --git a/tests/PHPUnit/CustomAffixes/A Test With Spaces.php b/tests/PHPUnit/CustomAffixes/A Test With Spaces.php
new file mode 100644
index 00000000..28497a1e
--- /dev/null
+++ b/tests/PHPUnit/CustomAffixes/A Test With Spaces.php	
@@ -0,0 +1,3 @@
+<?php
+
+it(sprintf('runs file names like `%s`', basename(__FILE__)))->assertTrue(true);
diff --git a/tests/PHPUnit/CustomAffixes/AdditionalFileExtension.spec.php b/tests/PHPUnit/CustomAffixes/AdditionalFileExtension.spec.php
new file mode 100644
index 00000000..28497a1e
--- /dev/null
+++ b/tests/PHPUnit/CustomAffixes/AdditionalFileExtension.spec.php
@@ -0,0 +1,3 @@
+<?php
+
+it(sprintf('runs file names like `%s`', basename(__FILE__)))->assertTrue(true);
diff --git a/tests/PHPUnit/CustomAffixes/ManyExtensions.class.test.php b/tests/PHPUnit/CustomAffixes/ManyExtensions.class.test.php
new file mode 100644
index 00000000..28497a1e
--- /dev/null
+++ b/tests/PHPUnit/CustomAffixes/ManyExtensions.class.test.php
@@ -0,0 +1,3 @@
+<?php
+
+it(sprintf('runs file names like `%s`', basename(__FILE__)))->assertTrue(true);
diff --git a/tests/PHPUnit/CustomAffixes/Test 'Case' With Quotes.php b/tests/PHPUnit/CustomAffixes/Test 'Case' With Quotes.php
new file mode 100644
index 00000000..28497a1e
--- /dev/null
+++ b/tests/PHPUnit/CustomAffixes/Test 'Case' With Quotes.php	
@@ -0,0 +1,3 @@
+<?php
+
+it(sprintf('runs file names like `%s`', basename(__FILE__)))->assertTrue(true);
diff --git a/tests/PHPUnit/CustomAffixes/kebab-case-spec.php b/tests/PHPUnit/CustomAffixes/kebab-case-spec.php
new file mode 100644
index 00000000..28497a1e
--- /dev/null
+++ b/tests/PHPUnit/CustomAffixes/kebab-case-spec.php
@@ -0,0 +1,3 @@
+<?php
+
+it(sprintf('runs file names like `%s`', basename(__FILE__)))->assertTrue(true);
diff --git a/tests/PHPUnit/CustomAffixes/snake_case_spec.php b/tests/PHPUnit/CustomAffixes/snake_case_spec.php
new file mode 100644
index 00000000..28497a1e
--- /dev/null
+++ b/tests/PHPUnit/CustomAffixes/snake_case_spec.php
@@ -0,0 +1,3 @@
+<?php
+
+it(sprintf('runs file names like `%s`', basename(__FILE__)))->assertTrue(true);
diff --git a/tests/Visual/Success.php b/tests/Visual/Success.php
index 1323da5b..8c5e1d6f 100644
--- a/tests/Visual/Success.php
+++ b/tests/Visual/Success.php
@@ -13,7 +13,13 @@ test('visual snapshot of test suite on success', function () {
 
         $process->run();
 
-        return preg_replace('#\\x1b[[][^A-Za-z]*[A-Za-z]#', '', $process->getOutput());
+        return preg_replace([
+            '#\\x1b[[][^A-Za-z]*[A-Za-z]#',
+            '/(Tests\\\PHPUnit\\\CustomAffixes\\\InvalidTestName)([A-Za-z0-9]*)/',
+        ], [
+            '',
+            '$1',
+        ], $process->getOutput());
     };
 
     if (getenv('REBUILD_SNAPSHOTS')) {