Implement freeze the app states

kobin/app.py

@@ -22,6 +22,7 @@ def index() -> Response:
 import os
 import traceback
 from urllib.parse import urljoin
+import warnings
 
 from .routes import Router
 from .requests import request
@@ -39,6 +40,15 @@ def __init__(self, config=None):
         self.before_request_callbacks = []
         self.after_request_callbacks = []
         self.logger = self.config.get('LOGGER')
+        self._frozen = False
+
+    def __setattr__(self, *args, **kwargs):
+        if '_frozen' in dir(self):
+            if self._frozen:
+                warnings.warn("Cannot Change the state of started application!",
+                              stacklevel=2)
+        else:
+            super().__setattr__(*args, **kwargs)
 
     def route(self, rule=None, method='GET', name=None, callback=None):
         def decorator(callback_func):
@@ -83,6 +93,8 @@ def _handle(self, environ):
 
     def __call__(self, environ, start_response):
         """It is called when receive http request."""
+        if not self._frozen:
+            self._frozen = True
         response = self._handle(environ)
         start_response(response.status, response.headerlist)
         return response.body

kobin/app.pyi

@@ -21,6 +21,7 @@ class Kobin:
     logger: Logger
     before_request_callbacks: List[Callable[[], None]]
     after_request_callbacks: List[Callable[[BaseResponse], Union[None, BaseResponse]]]
+    _frozen: bool
 
     def __init__(self, config: Dict[str, Any] = ...) -> None: ...
     def route(self, rule: str = ..., method: str = ..., name: str = ...,

tests/test_apps.py

@@ -177,6 +177,26 @@ def test_after_request(self):
         self.assertEqual('200 OK', response.status)
 
 
+class KobinFrozenTests(TestCase):
+    def setUp(self):
+        self.app = Kobin(config={'DEBUG': True})
+        self.before_counter = 0
+
+        @self.app.route('/')
+        def dummy_func():
+            return Response('hello')
+
+    def test_can_change_state_before_running(self):
+        test_env = {'REQUEST_METHOD': 'GET', 'PATH_INFO': '/'}
+
+        def dummy_start_response(s, h):
+            pass
+
+        self.app(test_env, dummy_start_response)
+        self.app.config = {'foo': 'bar'}
+        self.assertNotIn('foo', self.app.config)
+
+
 class ConfigTests(TestCase):
     def setUp(self):
         self.base_path = os.path.dirname(os.path.abspath(__file__))
@@ -210,6 +230,7 @@ def test_load_jinja2_env_with_globals(self):
     def test_load_jinja2_env_with_filters(self):
         def foo_filter(x):
             return x * 2
+
         env = load_jinja2_env('.', global_filters={'foo': foo_filter})
         self.assertEqual(foo_filter, env.filters['foo'])