diff --git a/tests/ACL/ACLScannerTest.php b/tests/ACL/ACLScannerTest.php
new file mode 100644
index 000000000..dae8dbf80
--- /dev/null
+++ b/tests/ACL/ACLScannerTest.php
@@ -0,0 +1,60 @@
+<?php
+
+namespace OCA\groupfolders\tests\ACL;
+
+use OC\Files\Storage\Temporary;
+use OCA\GroupFolders\ACL\ACLManager;
+use OCA\GroupFolders\ACL\ACLStorageWrapper;
+use OCP\Constants;
+use Test\TestCase;
+
+/**
+ * @group DB
+ */
+class ACLScannerTest extends TestCase {
+	private function getAclManager(array $rules): ACLManager {
+		$manager = $this->getMockBuilder(ACLManager::class)
+			->disableOriginalConstructor()
+			->getMock();
+		$manager->method('getACLPermissionsForPath')
+			->willReturnCallback(function($path) use ($rules) {
+				return $rules[$path] ?? Constants::PERMISSION_ALL;
+			});
+		return $manager;
+	}
+
+	public function testScanAclStorage() {
+		$baseStorage = new Temporary([]);
+		$baseStorage->mkdir('foo');
+		$baseStorage->mkdir('foo/bar');
+		$baseStorage->mkdir('foo/bar/asd');
+		$cache = $baseStorage->getCache();
+		$baseStorage->getScanner()->scan('');
+
+		$cache->update($cache->getId('foo/bar/asd'), ['size' => -1]);
+		$cache->calculateFolderSize('foo/bar');
+		$cache->calculateFolderSize('foo');
+
+		$this->assertEquals(-1, $cache->get('foo/bar')->getSize());
+
+		$acls = $this->getAclManager([
+			'foo/bar' => 0,
+			'foo/bar/asd' => 0,
+		]);
+
+		$aclStorage = new ACLStorageWrapper([
+			'storage' => $baseStorage,
+			'acl_manager' => $acls,
+			'in_share' => false,
+		]);
+
+		$scanner = $aclStorage->getScanner();
+		$aclCache = $aclStorage->getCache();
+		$scanner->scan('');
+
+		$this->assertEquals(0, $cache->get('foo/bar')->getSize());
+
+		$this->assertEquals(31, $cache->get('foo/bar')->getPermissions());
+		$this->assertEquals(false, $aclCache->get('foo/bar'));
+	}
+}