Add test app data

src/sakia/data/entities/app_data.py

@@ -3,4 +3,4 @@ import attr
 
 @attr.s()
 class AppData:
-    profiles = attr.ib(factory=list)
+    profiles = attr.ib(default=attr.Factory(list))

src/sakia/data/files/__init__.py

 from .user_parameters import UserParametersFile
+from .app_data import AppDataFile

src/sakia/tests/unit/data/test_appdata_file.py

+from sakia.data.entities import AppData
+from sakia.data.files import AppDataFile
+import tempfile
+import unittest
+import os
+
+
+class TestAppDataFile(unittest.TestCase):
+    def test_init_save_load(self):
+        file = os.path.join(tempfile.mkdtemp(), "params.json")
+        app_data = AppData()
+        app_data_file = AppDataFile(file)
+        app_data.profiles.append("default")
+        app_data_file.save(app_data)
+        app_data_2 = app_data_file.load()
+        self.assertEqual(app_data, app_data_2)