The build is failing on some database test. The tests pass locally. I don't think it is related to the changes I made, but if it is, please let me know, and I can try to figure out what is going on to fix it.

I saw another PR that has the same database error.

The tests are passing now :)

Cool. Thank you.

I just have one doubt here... Why does being an int works on Chrome? Does it work on other browsers as well?

Cool. Thank you.

I just have one doubt here... Why does being an int works on Chrome? Does it work on other browsers as well?

Let me investigate that this morning

Yes, int works in Firefox too. This behavior doesn't match the behavior described in https://www.rfc-editor.org/rfc/rfc6265#section-5.1.1 It does match the max-age behavior, which does take an integer that represents the seconds which the cookie is allowed to live.

My guess is that at some point browser programmers thought that max-age and expires were semantically the same, and allowed both integers and dates to set one or the other. In Firefox, dev tools shows expires as Expires/Max-Age. Then, although not part of the RFC, it seems to be a de-facto standard, either because the other browsers implement it that way, or because it was implemented this way years ago and no one touches the cookie code since it works.

Is there anything else to do?

Actually, I've found out why we accept int. It's because of how SimpleCookie is implemented in CPython:

https://github.com/python/cpython/blob/921f2353675ded86899c6dfdfc1c5c57bb998638/Lib/http/cookies.py#L408

werkzeug implements this logic like this: https://github.com/pallets/werkzeug/blob/3115aa6a6276939f5fd6efa46282e0256ff21f1a/src/werkzeug/http.py#L1228-L1230C29

Just some references.

If no one has anything against, I'm going to merge this when the release is ready.

Looks fine to me.

@florimondmanca I tried on this commit 6db2870

But it was flaky... Do you mean something different?

@Kludex I played with it locally. I feel like pytest's monkeypatch is just enough for our use case here, not really a need for a full-fledged extra library?

Diff:

diff --git a/requirements.txt b/requirements.txt
index 500a9b5..15aa541 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -9,7 +9,6 @@ flake8==3.9.2
 importlib-metadata==4.13.0
 isort==5.10.1
 mypy==0.991
-time-machine==2.9.0
 typing_extensions==4.4.0
 types-contextvars==2.4.7
 types-PyYAML==6.0.12.3
diff --git a/tests/test_responses.py b/tests/test_responses.py
index bf54772..aa2f5c4 100644
--- a/tests/test_responses.py
+++ b/tests/test_responses.py
@@ -1,6 +1,6 @@
 import os
-from datetime import datetime, timedelta, timezone
-from email.utils import format_datetime
+import datetime as dt
+import time
 from http.cookies import SimpleCookie
 
 import anyio
@@ -291,8 +291,10 @@ def test_file_response_with_inline_disposition(tmpdir, test_client_factory):
     assert response.headers["content-disposition"] == expected_disposition
 
 
-def test_set_cookie(test_client_factory, time_machine):
-    time_machine.move_to(datetime(2100, 1, 22, 12, 0, 0))
+def test_set_cookie(test_client_factory, monkeypatch):
+    # Mock time used as a reference for `Expires` by stdlib `SimpleCookie`.
+    mocked_now = dt.datetime(2100, 1, 22, 12, 0, 0, tzinfo=dt.timezone.utc)
+    monkeypatch.setattr(time, "time", lambda: mocked_now.timestamp())
 
     async def app(scope, receive, send):
         response = Response("Hello, world!", media_type="text/plain")
@@ -320,21 +322,23 @@ def test_set_cookie(test_client_factory, time_machine):
 
 
 @pytest.mark.parametrize(
-    "expires_factory",
+    "expires",
     [
-        lambda: datetime.now(timezone.utc) + timedelta(seconds=10),
-        lambda: format_datetime(
-            datetime.now(timezone.utc) + timedelta(seconds=10), usegmt=True
+        pytest.param(
+            dt.datetime(2100, 1, 22, 12, 0, 10, tzinfo=dt.timezone.utc), id="datetime"
         ),
-        lambda: 10,
+        pytest.param("Fri, 22 Jan 2100 12:00:10 GMT", id="str"),
+        pytest.param(10, id="int"),
     ],
 )
-def test_expires_on_set_cookie(test_client_factory, expires_factory, time_machine):
-    time_machine.move_to(datetime(2100, 1, 22, 12, 0, 0))
+def test_expires_on_set_cookie(test_client_factory, monkeypatch, expires):
+    # Mock time used as a reference for `Expires` by stdlib `SimpleCookie`.
+    mocked_now = dt.datetime(2100, 1, 22, 12, 0, 0, tzinfo=dt.timezone.utc)
+    monkeypatch.setattr(time, "time", lambda: mocked_now.timestamp())
 
     async def app(scope, receive, send):
         response = Response("Hello, world!", media_type="text/plain")
-        response.set_cookie("mycookie", "myvalue", expires=expires_factory())
+        response.set_cookie("mycookie", "myvalue", expires=expires)
         await response(scope, receive, send)
 
     client = test_client_factory(app)

@Kludex I played with it locally. I feel like pytest's monkeypatch is just enough for our use case here, not really a need for a full-fledged extra library?

Diff:

diff --git a/requirements.txt b/requirements.txt
index 500a9b5..15aa541 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -9,7 +9,6 @@ flake8==3.9.2
 importlib-metadata==4.13.0
 isort==5.10.1
 mypy==0.991
-time-machine==2.9.0
 typing_extensions==4.4.0
 types-contextvars==2.4.7
 types-PyYAML==6.0.12.3
diff --git a/tests/test_responses.py b/tests/test_responses.py
index bf54772..aa2f5c4 100644
--- a/tests/test_responses.py
+++ b/tests/test_responses.py
@@ -1,6 +1,6 @@
 import os
-from datetime import datetime, timedelta, timezone
-from email.utils import format_datetime
+import datetime as dt
+import time
 from http.cookies import SimpleCookie
 
 import anyio
@@ -291,8 +291,10 @@ def test_file_response_with_inline_disposition(tmpdir, test_client_factory):
     assert response.headers["content-disposition"] == expected_disposition
 
 
-def test_set_cookie(test_client_factory, time_machine):
-    time_machine.move_to(datetime(2100, 1, 22, 12, 0, 0))
+def test_set_cookie(test_client_factory, monkeypatch):
+    # Mock time used as a reference for `Expires` by stdlib `SimpleCookie`.
+    mocked_now = dt.datetime(2100, 1, 22, 12, 0, 0, tzinfo=dt.timezone.utc)
+    monkeypatch.setattr(time, "time", lambda: mocked_now.timestamp())
 
     async def app(scope, receive, send):
         response = Response("Hello, world!", media_type="text/plain")
@@ -320,21 +322,23 @@ def test_set_cookie(test_client_factory, time_machine):
 
 
 @pytest.mark.parametrize(
-    "expires_factory",
+    "expires",
     [
-        lambda: datetime.now(timezone.utc) + timedelta(seconds=10),
-        lambda: format_datetime(
-            datetime.now(timezone.utc) + timedelta(seconds=10), usegmt=True
+        pytest.param(
+            dt.datetime(2100, 1, 22, 12, 0, 10, tzinfo=dt.timezone.utc), id="datetime"
         ),
-        lambda: 10,
+        pytest.param("Fri, 22 Jan 2100 12:00:10 GMT", id="str"),
+        pytest.param(10, id="int"),
     ],
 )
-def test_expires_on_set_cookie(test_client_factory, expires_factory, time_machine):
-    time_machine.move_to(datetime(2100, 1, 22, 12, 0, 0))
+def test_expires_on_set_cookie(test_client_factory, monkeypatch, expires):
+    # Mock time used as a reference for `Expires` by stdlib `SimpleCookie`.
+    mocked_now = dt.datetime(2100, 1, 22, 12, 0, 0, tzinfo=dt.timezone.utc)
+    monkeypatch.setattr(time, "time", lambda: mocked_now.timestamp())
 
     async def app(scope, receive, send):
         response = Response("Hello, world!", media_type="text/plain")
-        response.set_cookie("mycookie", "myvalue", expires=expires_factory())
+        response.set_cookie("mycookie", "myvalue", expires=expires)
         await response(scope, receive, send)
 
     client = test_client_factory(app)

I've applied this. Thanks!