Add the AppState model

This allows setting application state during run time

tests/test_app_state.py

@@ -0,0 +1,49 @@
+# Calendar.social
+# Copyright (C) 2018  Gergely Polonkai
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+def test_app_state_set(database):
+    from calsocial.models import db, AppState
+
+    AppState['test'] = 'value'
+
+    state = AppState.query \
+                    .filter(AppState.env == 'testing') \
+                    .filter(AppState.key == 'test') \
+                    .one()
+
+    assert state.value == 'value'
+
+
+def test_app_state_get(database):
+    from calsocial.models import db, AppState
+
+    state = AppState(env='testing', key='test', value='value')
+    db.session.add(state)
+    db.session.commit()
+
+    assert AppState['test'] == 'value'
+
+
+def test_app_state_setdefault(database):
+    from calsocial.models import AppState
+
+    AppState['test'] = 'value'
+    AppState.setdefault('test', 'new value')
+
+    assert AppState['test'] == 'value'
+
+    AppState.setdefault('other_test', 'value')
+    assert AppState['other_test'] == 'value'