Config scan from bot channel implementation

tests/test_config.py

@@ -0,0 +1,44 @@
+from breadtube_bot.config import Config
+
+import pytest
+
+
+def test_empty():
+    with pytest.raises(RuntimeError, match='Cannot load config: empty input'):
+        Config.from_str('')
+
+
+def test_wrong_header():
+    with pytest.raises(RuntimeError, match='Cannot load config: first line is not "config"'):
+        Config.from_str('connfig')
+
+
+def test_lacking_key():
+    expected_config = Config(bot_role='test-role', request_timeout=5.5)
+    config = Config.from_str(
+        'config\n'
+        f'request_timeout={expected_config.request_timeout}\n'
+        f'bot_role={expected_config.bot_role}')
+    assert config == expected_config
+
+
+def test_wrong_key():
+    with pytest.raises(RuntimeError, match=('Invalid config: invalid key bot_channel_init at line 2')):
+        Config.from_str('config\nrequest_timeout=3.\nbot_channel_init=2')
+
+
+def test_duplicated_key():
+    with pytest.raises(RuntimeError, match=('Invalid config: duplicated key request_timeout at line 3')):
+        Config.from_str('config\nrequest_timeout=3.\nbot_channel_init_retries=2\nrequest_timeout=5.')
+
+
+def test_correct_config():
+    expected_config = Config(bot_channel='test-channel', bot_role='test-role', bot_channel_init_retries=298,
+                             request_timeout=5.5)
+    config = Config.from_str(
+        'config\n'
+        f'request_timeout={expected_config.request_timeout}\n'
+        f'bot_channel_init_retries={expected_config.bot_channel_init_retries}\n'
+        f'bot_channel={expected_config.bot_channel}\n'
+        f'bot_role={expected_config.bot_role}')
+    assert config == expected_config