add DB tests for credentials manager

these are actually expected to FAIL, because NULL as a userid is not
allowed in the schema, but documented to be used on the source

Signed-off-by: Arthur Schiwon <blizzz@arthur-schiwon.de>

tests/lib/Security/CredentialsManagerTest.php

@@ -27,6 +27,9 @@ use OCP\IDBConnection;
 use OCP\ILogger;
 use OCP\Security\ICrypto;
 
+/**
+ * @group DB
+ */
 class CredentialsManagerTest extends \Test\TestCase {
 
 	/** @var ICrypto */
@@ -106,4 +109,34 @@ class CredentialsManagerTest extends \Test\TestCase {
 
 		$this->manager->retrieve($userId, $identifier);
 	}
+
+	/**
+	 * @dataProvider credentialsProvider
+	 */
+	public function testWithDB($userId, $identifier) {
+		$credentialsManager = \OC::$server->getCredentialsManager();
+
+		$secrets = 'Open Sesame';
+
+		$credentialsManager->store($userId, $identifier, $secrets);
+		$received = $credentialsManager->retrieve($userId, $identifier);
+
+		$this->assertSame($secrets, $received);
+
+		$removedRows = $credentialsManager->delete($userId, $identifier);
+		$this->assertSame(1, $removedRows);
+	}
+
+	public function credentialsProvider() {
+		return [
+			[
+				'alice',
+				'privateCredentials'
+			],
+			[
+				null,
+				'systemCredentials'
+			]
+		];
+	}
 }