- Fixing SystemResource

- Adding tests for StorageManager
- Updating doc

tests/datasets/storage/database.fixture.php

@@ -0,0 +1,40 @@
+<?php
+
+return [
+	'photo'   => [
+		// move from data-attribute to storage backend
+		[
+			'id'            => 1,
+			'backend-class' => null,
+			'backend-ref'   => 'f0c0d0i2',
+			'data'          => 'without class',
+		],
+		// move from storage-backend to maybe filesystem backend, skip at database backend
+		[
+			'id'            => 2,
+			'backend-class' => 'Database',
+			'backend-ref'   => 1,
+			'data'          => '',
+		],
+		// move data if invalid storage
+		[
+			'id'            => 3,
+			'backend-class' => 'invalid!',
+			'backend-ref'   => 'unimported',
+			'data'          => 'invalid data moved',
+		],
+		// skip everytime because of invalid storage and no data
+		[
+			'id'            => 3,
+			'backend-class' => 'invalid!',
+			'backend-ref'   => 'unimported',
+			'data'          => '',
+		],
+	],
+	'storage' => [
+		[
+			'id'   => 1,
+			'data' => 'inside database',
+		],
+	],
+];