diff --git a/composer.json b/composer.json
index f708bf3..f6424ba 100644
--- a/composer.json
+++ b/composer.json
@@ -12,7 +12,8 @@
     "autoload-dev": {
         "psr-4": {
             "Typo3Update\\Tests\\": "tests/",
-            "PHP_CodeSniffer\\": "vendor/squizlabs/php_codesniffer/src/"
+            "PHP_CodeSniffer\\": "vendor/squizlabs/php_codesniffer/src/",
+            "PHP_CodeSniffer\\Tests\\": "vendor/squizlabs/php_codesniffer/tests/"
         }
     },
     "autoload": {
diff --git a/tests/AbstractSniffUnitTest.php b/tests/AbstractSniffUnitTest.php
new file mode 100644
index 0000000..ac6b21d
--- /dev/null
+++ b/tests/AbstractSniffUnitTest.php
@@ -0,0 +1,113 @@
+<?php
+namespace Typo3Update\Tests;
+
+/*
+ * Copyright (C) 2017  Daniel Siepmann <coding@daniel-siepmann.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+use PHP_CodeSniffer\Tests\Standards\AbstractSniffUnitTest as PhpCsAbstractSniffUnitTest;
+use Symfony\Component\Finder\Finder;
+
+use PHP_CodeSniffer\Tests\Standards\AllSniffs;
+
+abstract class AbstractSniffUnitTest extends PhpCsAbstractSniffUnitTest
+{
+    protected function setUp()
+    {
+        // Trigger include for bootstrapping.
+        // TODO: Move to bootstrap file.
+        class_exists(AllSniffs::class);
+        $GLOBALS['PHP_CODESNIFFER_SNIFF_CODES'] = [];
+        $GLOBALS['PHP_CODESNIFFER_FIXABLE_CODES'] = [];
+
+        $class = get_class($this);
+        $GLOBALS['PHP_CODESNIFFER_STANDARD_DIRS'][$class] = implode(
+            DIRECTORY_SEPARATOR,
+            [__DIR__, '..', 'src', 'Standards', 'Typo3Update', 'Sniffs', '']
+        );
+        $GLOBALS['PHP_CODESNIFFER_TEST_DIRS'][$class] = $this->getFixturePath();
+
+        parent::setUp();
+    }
+
+    /**
+     * Returns the lines where errors should occur.
+     *
+     * The key of the array should represent the line number and the value
+     * should represent the number of errors that should occur on that line.
+     *
+     * @return array<int, int>
+     */
+    protected function getErrorList()
+    {
+        return $this->getExpectdOutput()['ERROR'];
+    }
+
+    /**
+     * Returns the lines where warnings should occur.
+     *
+     * The key of the array should represent the line number and the value
+     * should represent the number of warnings that should occur on that line.
+     *
+     * @return array(int => int)
+     */
+    protected function getWarningList()
+    {
+        return $this->getExpectdOutput()['WARNING'];
+    }
+
+    protected function getFixturePath()
+    {
+        return implode(
+            DIRECTORY_SEPARATOR,
+            [__DIR__, 'Fixtures', 'Standards', 'Typo3Update', 'Sniffs', '']
+        );
+    }
+
+    protected function getExpectdOutput()
+    {
+        $list = [
+            'WARNING' => [],
+            'ERROR' => [],
+        ];
+
+        $file = $this->getFixturePath() . implode(
+            DIRECTORY_SEPARATOR,
+            array_slice(explode('\\', str_replace('Sniff', '', get_class($this))), 2)
+        ) . 'Expected.json';
+
+        if (!is_file($file)) {
+            throw new \Exception('Could not load file: ' . $file, 1491486050);
+        }
+
+        $content = json_decode(file_get_contents($file), true);
+
+        foreach ($content['files']['InputFileForIssues.php']['messages'] as $message) {
+            $type = $message['type'];
+
+            if (!isset($list[$type][$message['line']])) {
+                $list[$type][$message['line']] = 1;
+                continue;
+            }
+
+            ++$list[$type][$message['line']];
+        }
+
+        return $list;
+    }
+}
diff --git a/tests/Feature/LegacyClassnameMappingTest.php b/tests/Feature/LegacyClassnameMappingTest.php
index 7a169d9..acda663 100644
--- a/tests/Feature/LegacyClassnameMappingTest.php
+++ b/tests/Feature/LegacyClassnameMappingTest.php
@@ -54,7 +54,7 @@ class LegacyClassnameMappingTest extends TestCase
         $this->fileSystem = vfsStream::setup('root', null, [
             'LegacyClassnames.php' => file_get_contents($this->getFixturePath('MappingContent.php')),
         ]);
-        Config::setConfigData('mappingFile', vfsStream::url('root/LegacyClassnames.php'));
+        // Config::setConfigData('mappingFile', vfsStream::url('root/LegacyClassnames.php'));
 
         $this->subject = LegacyClassnameMapping::getInstance();
     }
diff --git a/tests/Fixtures/Standards/Typo3Update/Sniffs/Classname/InheritanceSniff/Expected.diff b/tests/Fixtures/Standards/Typo3Update/Sniffs/Classname/InheritanceExpected.diff
similarity index 100%
rename from tests/Fixtures/Standards/Typo3Update/Sniffs/Classname/InheritanceSniff/Expected.diff
rename to tests/Fixtures/Standards/Typo3Update/Sniffs/Classname/InheritanceExpected.diff
diff --git a/tests/Fixtures/Standards/Typo3Update/Sniffs/Classname/InheritanceSniff/Expected.json b/tests/Fixtures/Standards/Typo3Update/Sniffs/Classname/InheritanceExpected.json
similarity index 100%
rename from tests/Fixtures/Standards/Typo3Update/Sniffs/Classname/InheritanceSniff/Expected.json
rename to tests/Fixtures/Standards/Typo3Update/Sniffs/Classname/InheritanceExpected.json
diff --git a/tests/Fixtures/Standards/Typo3Update/Sniffs/Classname/InheritanceSniff/InputFileForIssues.php b/tests/Fixtures/Standards/Typo3Update/Sniffs/Classname/InheritanceUnitTest.inc
similarity index 100%
rename from tests/Fixtures/Standards/Typo3Update/Sniffs/Classname/InheritanceSniff/InputFileForIssues.php
rename to tests/Fixtures/Standards/Typo3Update/Sniffs/Classname/InheritanceUnitTest.inc
diff --git a/tests/Sniffs/Classname/InheritanceSniffTest.php b/tests/Sniffs/Classname/InheritanceSniffTest.php
index 56c8bcb..dc4d941 100644
--- a/tests/Sniffs/Classname/InheritanceSniffTest.php
+++ b/tests/Sniffs/Classname/InheritanceSniffTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Typo3Update\Tests\Sniffs\Classname;
+namespace Typo3Update\Tests\Classname;
 
 /*
  * Copyright (C) 2017  Daniel Siepmann <coding@daniel-siepmann.de>
@@ -21,8 +21,8 @@ namespace Typo3Update\Tests\Sniffs\Classname;
  * 02110-1301, USA.
  */
 
-use Typo3Update\Tests\SniffsTest;
+use Typo3Update\Tests\AbstractSniffUnitTest;
 
-class InheritanceSniffTest extends SniffsTest
+class InheritanceSniff extends AbstractSniffUnitTest
 {
 }