diff --git a/composer.json b/composer.json
index cd2d480..5f79fca 100644
--- a/composer.json
+++ b/composer.json
@@ -23,7 +23,8 @@
         "shipmonk/coding-standard": "^0.1.3",
         "shipmonk/composer-dependency-analyser": "^1.8.1",
         "shipmonk/dead-code-detector": "^0.9.0",
-        "shipmonk/name-collision-detector": "^2.1.1"
+        "shipmonk/name-collision-detector": "^2.1.1",
+        "shipmonk/phpstan-dev": "^0.1.1"
     },
     "autoload": {
         "psr-4": {
diff --git a/composer.lock b/composer.lock
index 6380b1b..8b7ca12 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "c7e2df2cf10e92a7163b989c71ac0396",
+    "content-hash": "6fb0c988abe9eb2fd7f966302480f059",
     "packages": [
         {
             "name": "phpstan/phpstan",
@@ -3130,6 +3130,61 @@
             },
             "time": "2024-03-01T13:26:32+00:00"
         },
+        {
+            "name": "shipmonk/phpstan-dev",
+            "version": "0.1.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/shipmonk-rnd/phpstan-dev.git",
+                "reference": "ec564f68d893fa966f70afa8274d03fa8f0103df"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/shipmonk-rnd/phpstan-dev/zipball/ec564f68d893fa966f70afa8274d03fa8f0103df",
+                "reference": "ec564f68d893fa966f70afa8274d03fa8f0103df",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^7.4 || ^8.0",
+                "phpstan/phpstan": "^2.1.8"
+            },
+            "require-dev": {
+                "editorconfig-checker/editorconfig-checker": "^10.6.0",
+                "ergebnis/composer-normalize": "^2.45.0",
+                "phpstan/phpstan-deprecation-rules": "^2.0.1",
+                "phpstan/phpstan-phpunit": "^2.0.4",
+                "phpstan/phpstan-strict-rules": "^2.0.3",
+                "phpunit/phpunit": "^9.6.22",
+                "shipmonk/composer-dependency-analyser": "^1.8.1",
+                "shipmonk/dead-code-detector": "^0.9.0",
+                "shipmonk/name-collision-detector": "^2.1.1",
+                "slevomat/coding-standard": "^8.16.0"
+            },
+            "suggest": {
+                "phpunit/phpunit": "^9.6.22 for running tests that use RuleTestCase"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "ShipMonk\\PHPStanDev\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "description": "Development utilities for PHPStan rules testing, extracted from shipmonk/phpstan-rules",
+            "keywords": [
+                "PHPStan",
+                "static analysis",
+                "testing"
+            ],
+            "support": {
+                "issues": "https://github.com/shipmonk-rnd/phpstan-dev/issues",
+                "source": "https://github.com/shipmonk-rnd/phpstan-dev/tree/0.1.1"
+            },
+            "time": "2025-08-25T12:16:48+00:00"
+        },
         {
             "name": "slevomat/coding-standard",
             "version": "8.19.1",
diff --git a/tests/RuleTestCase.php b/tests/RuleTestCase.php
index 54da771..c1b28ea 100644
--- a/tests/RuleTestCase.php
+++ b/tests/RuleTestCase.php
@@ -2,28 +2,14 @@
 
 namespace ShipMonk\PHPStan;
 
-use LogicException;
-use PHPStan\Analyser\Error;
 use PHPStan\Rules\Rule;
-use PHPStan\Testing\RuleTestCase as OriginalRuleTestCase;
-use function array_values;
-use function explode;
-use function file_get_contents;
-use function file_put_contents;
-use function implode;
-use function ksort;
-use function preg_match;
-use function preg_match_all;
-use function preg_replace;
-use function sprintf;
-use function trim;
-use function uniqid;
+use ShipMonk\PHPStanDev\RuleTestCase as ShipMonkDevRuleTestCase;
 
 /**
  * @template TRule of Rule
- * @extends OriginalRuleTestCase<TRule>
+ * @extends ShipMonkDevRuleTestCase<TRule>
  */
-abstract class RuleTestCase extends OriginalRuleTestCase
+abstract class RuleTestCase extends ShipMonkDevRuleTestCase
 {
 
     protected function analyseFile(
@@ -31,137 +17,7 @@ protected function analyseFile(
         bool $autofix = false
     ): void
     {
-        $analyserErrors = $this->gatherAnalyserErrors([$file]);
-
-        if ($autofix === true) {
-            $this->autofix($file, $analyserErrors);
-            self::fail("File $file was autofixed. This setup should never remain in the codebase.");
-        }
-
-        $actualErrors = $this->processActualErrors($analyserErrors);
-        $expectedErrors = $this->parseExpectedErrors($file);
-
-        self::assertSame(
-            implode("\n", $expectedErrors) . "\n",
-            implode("\n", $actualErrors) . "\n",
-        );
-    }
-
-    /**
-     * @param list<Error> $actualErrors
-     * @return list<string>
-     */
-    protected function processActualErrors(array $actualErrors): array
-    {
-        $resultToAssert = [];
-
-        foreach ($actualErrors as $error) {
-            $usedLine = $error->getLine() ?? -1;
-            $key = sprintf('%04d', $usedLine) . '-' . uniqid();
-            $resultToAssert[$key] = $this->formatErrorForAssert($error->getMessage(), $usedLine);
-
-            self::assertNotNull($error->getIdentifier(), "Missing error identifier for error: {$error->getMessage()}");
-            self::assertStringStartsWith('shipmonk.', $error->getIdentifier(), "Unexpected error identifier for: {$error->getMessage()}");
-        }
-
-        ksort($resultToAssert);
-
-        return array_values($resultToAssert);
-    }
-
-    /**
-     * @return list<string>
-     */
-    private function parseExpectedErrors(string $file): array
-    {
-        $fileLines = $this->getFileLines($file);
-        $expectedErrors = [];
-
-        foreach ($fileLines as $line => $row) {
-            /** @var array{0: list<string>, 1: list<non-empty-string>} $matches */
-            $matched = preg_match_all('#// error:(.+)#', $row, $matches);
-
-            if ($matched === false) {
-                throw new LogicException('Error while matching errors');
-            }
-
-            if ($matched === 0) {
-                continue;
-            }
-
-            foreach ($matches[1] as $error) {
-                $actualLine = $line + 1;
-                $key = sprintf('%04d', $actualLine) . '-' . uniqid();
-                $expectedErrors[$key] = $this->formatErrorForAssert(trim($error), $actualLine);
-            }
-        }
-
-        ksort($expectedErrors);
-
-        return array_values($expectedErrors);
-    }
-
-    private function formatErrorForAssert(
-        string $message,
-        int $line
-    ): string
-    {
-        return sprintf('%02d: %s', $line, $message);
-    }
-
-    /**
-     * @param list<Error> $analyserErrors
-     */
-    private function autofix(
-        string $file,
-        array $analyserErrors
-    ): void
-    {
-        $errorsByLines = [];
-
-        foreach ($analyserErrors as $analyserError) {
-            $line = $analyserError->getLine();
-
-            if ($line === null) {
-                throw new LogicException('Error without line number: ' . $analyserError->getMessage());
-            }
-
-            $errorsByLines[$line] = $analyserError;
-        }
-
-        $fileLines = $this->getFileLines($file);
-
-        foreach ($fileLines as $line => &$row) {
-            if (!isset($errorsByLines[$line + 1])) {
-                continue;
-            }
-
-            $errorCommentPattern = '~ ?//.*$~';
-            $errorMessage = $errorsByLines[$line + 1]->getMessage();
-            $errorComment = ' // error: ' . $errorMessage;
-
-            if (preg_match($errorCommentPattern, $row) === 1) {
-                $row = preg_replace($errorCommentPattern, $errorComment, $row);
-            } else {
-                $row .= $errorComment;
-            }
-        }
-
-        file_put_contents($file, implode("\n", $fileLines));
-    }
-
-    /**
-     * @return list<string>
-     */
-    private function getFileLines(string $file): array
-    {
-        $fileData = file_get_contents($file);
-
-        if ($fileData === false) {
-            throw new LogicException('Error while reading data from ' . $file);
-        }
-
-        return explode("\n", $fileData);
+        $this->analyzeFiles([$file], $autofix);
     }
 
 }