Fix empty str(exception) when initialized with kwargs (#2181)

Co-authored-by: Marcelo Trylesinski <marcelotryle@gmail.com>

starlette/exceptions.py

@@ -18,6 +18,9 @@ def __init__(
         self.detail = detail
         self.headers = headers
 
+    def __str__(self) -> str:
+        return f"{self.status_code}: {self.detail}"
+
     def __repr__(self) -> str:
         class_name = self.__class__.__name__
         return f"{class_name}(status_code={self.status_code!r}, detail={self.detail!r})"
@@ -28,6 +31,9 @@ def __init__(self, code: int, reason: typing.Optional[str] = None) -> None:
         self.code = code
         self.reason = reason or ""
 
+    def __str__(self) -> str:
+        return f"{self.code}: {self.reason}"
+
     def __repr__(self) -> str:
         class_name = self.__class__.__name__
         return f"{class_name}(code={self.code!r}, reason={self.reason!r})"

tests/test_exceptions.py

@@ -144,6 +144,12 @@ async def app(scope, receive, send):
     assert response.text == ""
 
 
+def test_http_str():
+    assert str(HTTPException(status_code=404)) == "404: Not Found"
+    assert str(HTTPException(404, "Not Found: foo")) == "404: Not Found: foo"
+    assert str(HTTPException(404, headers={"key": "value"})) == "404: Not Found"
+
+
 def test_http_repr():
     assert repr(HTTPException(404)) == (
         "HTTPException(status_code=404, detail='Not Found')"
@@ -160,6 +166,11 @@ class CustomHTTPException(HTTPException):
     )
 
 
+def test_websocket_str():
+    assert str(WebSocketException(1008)) == "1008: "
+    assert str(WebSocketException(1008, "Policy Violation")) == "1008: Policy Violation"
+
+
 def test_websocket_repr():
     assert repr(WebSocketException(1008, reason="Policy Violation")) == (
         "WebSocketException(code=1008, reason='Policy Violation')"