Refactor handle unexpected exception

kobin/app.py

@@ -72,12 +72,7 @@ def _handle(self, environ):
         except HTTPError as e:
             response = e
         except BaseException as e:
-            traceback.print_tb(e.__traceback__)
-            if self.config['DEBUG']:
-                message = '\n'.join(traceback.format_tb(e.__traceback__))
-            else:
-                message = 'Internal Server Error'
-            response = HTTPError(message, 500)
+            response = _handle_unexpected_exception(e, self.config.get('DEBUG'))
         return response
 
     def wsgi(self, environ, start_response):
@@ -90,6 +85,20 @@ def __call__(self, environ, start_response):
         return self.wsgi(environ, start_response)
 
 
+def _get_traceback_message(e):
+    message = '\n'.join(traceback.format_tb(e.__traceback__))
+    return message
+
+
+def _handle_unexpected_exception(e, debug):
+    if debug:
+        message = _get_traceback_message(e)
+    else:
+        message = 'Internal Server Error'
+    response = HTTPError(message, 500)
+    return response
+
+
 class Config(dict):
     """This class manages your application configs.
     """

kobin/app.pyi

@@ -3,7 +3,7 @@ from types import ModuleType
 from jinja2 import Environment  # type: ignore
 
 from .routes import Router
-from .environs import BaseResponse
+from .environs import BaseResponse, Response
 
 
 WSGIEnvironValue = TypeVar('WSGIEnvironValue')
@@ -30,6 +30,8 @@ class Kobin:
     def wsgi(self, environ: WSGIEnviron, start_response: StartResponse) -> WSGIResponse: ...
     def __call__(self, environ: WSGIEnviron, start_response: StartResponse) -> WSGIResponse: ...
 
+def _get_traceback_message(e: BaseException) -> str: ...
+def _handle_unexpected_exception(e: BaseException, debug: bool) -> Response: ...
 
 class Config(dict):
     _template_env: Environment

tests/test_apps.py

@@ -1,6 +1,10 @@
 import os
 from unittest import TestCase
-from kobin import Kobin, Config, Response, load_config_from_module, load_config_from_pyfile
+from kobin import (
+    Kobin, Response,
+    Config, load_config_from_module, load_config_from_pyfile
+)
+from kobin.app import _handle_unexpected_exception, _get_traceback_message
 
 
 class KobinTests(TestCase):
@@ -117,6 +121,38 @@ def test_after_request(self):
         self.assertIn(('Foo', 'Bar'), response.headerlist)
 
 
+class HandleUnexpectedExceptionTests(TestCase):
+    def test_get_traceback_message(self):
+        try:
+            1 / 0
+        except BaseException as e:
+            actual = _get_traceback_message(e)
+        else:
+            actual = "Exception is not raised."
+        cause_of_exception = 'x = 1/0'
+        self.assertIn(cause_of_exception, actual)
+
+    def test_handle_unexpected_exception_should_return_500(self):
+        try:
+            1 / 0
+        except BaseException as e:
+            actual = _handle_unexpected_exception(e, False)
+        else:
+            actual = "Exception is not raised."
+        expected_status_code = 500
+        self.assertEqual(actual.status_code, expected_status_code)
+
+    def test_handle_unexpected_exception_body(self):
+        try:
+            1 / 0
+        except BaseException as e:
+            actual = _handle_unexpected_exception(e, False)
+        else:
+            actual = "Exception is not raised."
+        expected_body = [b'Internal Server Error']
+        self.assertEqual(actual.body, expected_body)
+
+
 class KobinAfterHookTests(TestCase):
     def setUp(self):
         self.app = Kobin()