Config templating (#5900)

Template config files

* Imagine a system composed entirely of x, y, z etc and the basic operations..

Wait George, why XOR? Why not just neq?

George: Eh, I didn't think of that..

Co-Authored-By: Erik Johnston <erik@matrix.org>

tests/config/test_database.py

@@ -0,0 +1,52 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 New Vector Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import yaml
+
+from synapse.config.database import DatabaseConfig
+
+from tests import unittest
+
+
+class DatabaseConfigTestCase(unittest.TestCase):
+    def test_database_configured_correctly_no_database_conf_param(self):
+        conf = yaml.safe_load(
+            DatabaseConfig().generate_config_section("/data_dir_path", None)
+        )
+
+        expected_database_conf = {
+            "name": "sqlite3",
+            "args": {"database": "/data_dir_path/homeserver.db"},
+        }
+
+        self.assertEqual(conf["database"], expected_database_conf)
+
+    def test_database_configured_correctly_database_conf_param(self):
+
+        database_conf = {
+            "name": "my super fast datastore",
+            "args": {
+                "user": "matrix",
+                "password": "synapse_database_password",
+                "host": "synapse_database_host",
+                "database": "matrix",
+            },
+        }
+
+        conf = yaml.safe_load(
+            DatabaseConfig().generate_config_section("/data_dir_path", database_conf)
+        )
+
+        self.assertEqual(conf["database"], database_conf)