Update MSC4311 tests to conform to the spec and better coverage by turt2live · Pull Request #796 · matrix-org/complement

turt2live · 2025-08-15T01:32:41Z

Update MSC4311 tests to conform to the spec. MSC4311 states that the client API should still use the stripped state event format. For the federation API, it should use full PDU's. MSC4311 also requires the m.room.create event be included in the list of stripped state.

"Stripped state" is a generic term that refers to simplified slice of state shared in invite_room_state/knock_room_state (invite_state/knock_state with /sync) before someone is joined to a room and can see the full room state.

This PR was originally authored by @turt2live taking a stab at fixing single the flawed test (self-reported: ~~"I have no idea what I'm doing" disclaimer goes here~~) but has since been taken over by @MadLittleMods. And has naturally evolved some new better test coverage as I've worked on a full solution.

Synapse PR: ~~element-hq/synapse#18822~~ element-hq/synapse#19723

The previous tests passed because of a flawed implementation in Synapse which is being removed in element-hq/synapse#19723 as well.

Dev notes

Running the tests with Synapse:

COMPLEMENT_DIR=../complement ./scripts-dev/complement.sh -run TestMSC4311StrippedStateClientAPI

COMPLEMENT_DIR=../complement ./scripts-dev/complement.sh -run TestMSC4311FullEventsOnStrippedStateFederation

COMPLEMENT_DIR=../complement ./scripts-dev/complement.sh -run TestMSC4311RejectInvalidStrippedStateFederation

go test ./match -v -count=1 -run TestJSONArraySome

kegsay · 2025-08-15T07:18:34Z

-				must.MatchGJSON(t, ev,
-					match.JSONKeyPresent("origin_server_ts"),
-				)
+	srv.Mux().HandleFunc("/_matrix/federation/v2/invite/{roomID}/{eventID}", srv.ValidFederationRequest(t, func(fr *fclient.FederationRequest, pathParams map[string]string) util.JSONResponse {


You should be able to alternatively use:

srv := federation.NewServer(t, deployment, federation.HandleInviteRequests(func(p gomatrixserverlib.PDU) { // checks here }), federation.HandleKeyRequests(), federation.HandleMakeSendJoinRequests(), federation.HandleTransactionRequests(nil, nil), )

I went down this route but the problem is that federation.HandleInviteRequests(...) doesn't allow you to inspect the invite_room_state yet. It would have to be updated to pass in the full invite request to the callback.

And gomatrixserverlib needs to be updated to handle the new world where invite_room_state can be stripped state or full PDUs.

We could have an infallible InviteV2Request.StrippedInviteRoomState() that would give a view of stripped state regardless of whether we were passed stripped or full PDU's (we can derive stripped state from the full PDU's). And then a fallible InviteV2Request.FullInviteRoomState() that would return an error if the homeserver didn't pass us full PDUs.

We would also need to update IRoomVersion to add new fields like CreateEventRequiredInInviteRoomState and ~~FullPDUInviteRoomState~~ (full PDU's can happen in any room version) so we can conditionally apply this behavior. Or maybe the flags could be combined as MSC4311InviteRoomState

If any of the events are not a PDU, not for the room ID specified, or fail signature checks, or the m.room.create event is missing, the receiving server MAY respond to invites with a 400 M_MISSING_PARAM standard Matrix error (new to the endpoint). For invites to room version 12+ rooms, servers SHOULD rather than MAY respond to such requests with 400 M_MISSING_PARAM.

-- matrix-org/matrix-spec-proposals#4311

But it doesn't seem possible to see. For example, Synapse strips it out when trying to view events, https://github.com/element-hq/synapse/blob/6100f6e4f7fb0c72f1ae2802683ebc811c0e3a77/synapse/events/utils.py#L590-L596

MadLittleMods · 2026-05-26T22:42:20Z

+// > error (new to the endpoint). For invites to room version 12+ rooms, servers
+// > SHOULD rather than MAY respond to such requests with `400 M_MISSING_PARAM`.
+func TestMSC4311RejectInvalidStrippedStateFederation(t *testing.T) {
+	runtime.SkipIf(t, runtime.Synapse)  // FIXME: Run these tests after 2027-06-01


Also cross-linked this in the Synapse codebase (see element-hq/synapse#19723)

Copilot

Pull request overview

This PR updates MSC4311 coverage for room version 12 by replacing an incorrect stripped-state test with client-server, federation, and rejection coverage, plus helper support for knock flows.

Changes:

Adds MSC4311 tests for client /sync stripped state and federation invite/knock stripped state.
Adds JSONArraySome matcher for asserting that at least one JSON array element matches.
Adds client and federation knock helpers used by the new tests.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
`tests/v12_test.go`	Replaces the old MSC4311 test with expanded client, federation, and invalid-state rejection tests.
`match/json.go`	Adds `JSONArraySome` matcher for “any element matches” assertions.
`federation/server.go`	Adds federation knock helper and strict `knock_room_state` validation option.
`client/client.go`	Adds client knock helper and fixes invite helper comments.

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See #796 (comment)

anoadragon453

Only nits below. Otherwise this LGTM!

anoadragon453 · 2026-05-28T15:52:06Z

+					match.JSONArraySome("invite_room_state", func(event gjson.Result) error {
+						// MSC4311 also mandates that `m.room.create` event is required
+						return should.MatchGJSON(event, match.JSONKeyEqual("type", "m.room.create"))
+					}),
+					match.JSONArrayEach("invite_room_state", func(event gjson.Result) error {
+						// Each event should have extra fields `origin_server_ts` that indicate we're
+						// seeing a full PDU and not just a "stripped state event"
+						return should.MatchGJSON(event, match.JSONKeyPresent("origin_server_ts"))


Seems like it'd make sense to extract this to a helper function at this point, given I've seen it about 4 times now.

I'd rather not (not totally convinced yet). They're all dealing with different field names which of course could be a function arg but the abstraction is just going to make things less clear what we care about.

See #796 (comment)

…and support MSC4311" See #796 (comment)

…over federation and always include `m.room.create` event (#19723) ### Background This PR was originally just trying to remove the flawed [MSC4311](matrix-org/matrix-spec-proposals#4311) partial implementation as client side API's like `/sync` should still use stripped events. But it turns out we were just re-using the client logic for the federation side and things might break if we didn't include the full `m.room.create` event so this PR now introduces MSC4311 support to use full PDU's in the `invite_room_state`/`knock_room_state` in the federation API's. The flawed implementation was originally introduced in 0eb7252 (no PR I assume because part of Hydra security fix) which was part of [Synapse v1.136.0](https://github.com/element-hq/synapse/blob/7530874a1250d6ad975b39582a784c594d29a505/CHANGES.md#synapse-11360-2025-08-12). Spawning from reviewing #19722 and noticing that we have [`TestMSC4311FullCreateEventOnStrippedState`](https://github.com/matrix-org/complement/blob/1e2e12eebc1edb27bbf12108ec849a8254b6ddcd/tests/v12_test.go#L1341-L1376) in Complement which already passes even though that test looks [flawed](matrix-org/complement#791 (comment)): > I think this test is mixing up what [MSC4311](matrix-org/matrix-spec-proposals#4311) proposes. Perhaps these were changes to the MSC that came after? > > For the client API's like `/sync`, it only proposes that `m.room.create` is a required *stripped* state event. > > For the federation API's, alongside requiring `m.room.create`, it also mandates using the full event PDU format for all events in the `invite_room_state`/`knock_room_state` on `m.room.member` events (in `unsigned`) ### What does this PR do? 1. Always use stripped state for client API's 1. Remove flawed [MSC4311](matrix-org/matrix-spec-proposals#4311) partial implementation (as explained above) 1. Sanitize stripped state when we receive events over federation 1. Use full PDU's when sending `invite_room_state`/`knock_room_state` over federation 1. Validate PDU's and warn when receiving `invite_room_state`/`knock_room_state` over federation 1. In the future, we will strictly validate and reject Complement tests: matrix-org/complement#796 --- Part of #19414

MadLittleMods · 2026-09-22T17:19:44Z

Thanks for the review @anoadragon453 🐏

Kudos to @turt2live for starting this a year ago 🐃

Try to modify MSC4311 test to meet new proposal

e5a5a87

This was referenced Aug 15, 2025

Use PDUs for stripped state over federation element-hq/synapse#18822

Closed

MSC4311: Ensuring the create event is available on invites matrix-org/matrix-spec-proposals#4311

Merged

kegsay reviewed Aug 15, 2025

View reviewed changes

Merge branch 'main' into travis/msc4311-v2

d98aae0

This was referenced Apr 23, 2026

Room version 12 tests #791

Merged

MSC4311: Use full PDU's in stripped state (like invite_room_state) over federation and always include m.room.create event element-hq/synapse#19723

Merged

MadLittleMods added 2 commits April 30, 2026 17:57

Merge branch 'main' into travis/msc4311-v2

1faef0d

More robust test

35dcccf

MadLittleMods reviewed May 1, 2026

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Comment thread tests/v12_test.go Outdated

MadLittleMods reviewed May 1, 2026

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Comment thread tests/v12_test.go Outdated

MadLittleMods added 2 commits May 1, 2026 19:04

Add TODO about testing knock_room_state

96b8d49

Fix raw bytes being encoded as event instead of actual JSON

795a951

MadLittleMods reviewed May 2, 2026

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Comment thread tests/v12_test.go Outdated

MadLittleMods mentioned this pull request May 4, 2026

4311 stripped state create event #871

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MadLittleMods reviewed May 4, 2026

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Comment thread tests/v12_test.go

MadLittleMods added 14 commits May 4, 2026 14:18

Use more specific type

47474a0

WIP: Add TestMSC4311CreateEventInStrippedStateClientApi

25ced8b

Use more robust MustSyncUntil

3256657

WIP: Add test for invite_room_state in client API

cabb542

But it doesn't seem possible to see. For example, Synapse strips it out when trying to view events, https://github.com/element-hq/synapse/blob/6100f6e4f7fb0c72f1ae2802683ebc811c0e3a77/synapse/events/utils.py#L590-L596

Remove invite_room_state client test

7171d67

Remove stray parallel

18d6da2

Better casing

5d61d01

Merge branch 'main' into travis/msc4311-v2

9f29477

Add client knock_state test

633c1a2

Add knock_room_state test (MustKnockRoom not implemented)

55df04e

Implement srv.MustKnockRoom

92cdd79

We're doing the TODO now

2523631

Split up tests

b4ab892

Add TestMSC4311RejectInvalidStrippedStateFederation

07c60fc

MadLittleMods reviewed May 26, 2026

View reviewed changes

Add note about this applying to other room versions

4b044a1

MadLittleMods changed the title ~~Try to modify MSC4311 test to meet new proposal~~ Update MSC4311 tests to conform to the spec May 27, 2026

MadLittleMods changed the title ~~Update MSC4311 tests to conform to the spec~~ Update MSC4311 tests to conform to the spec and better coverage May 27, 2026

MadLittleMods marked this pull request as ready for review May 27, 2026 21:04

MadLittleMods requested review from a team as code owners May 27, 2026 21:04

anoadragon453 requested a review from Copilot May 28, 2026 15:13

Copilot started reviewing on behalf of anoadragon453 May 28, 2026 15:14 View session

Copilot AI reviewed May 28, 2026

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Comment thread match/json.go Outdated

Comment thread match/json.go

Comment thread client/client.go

MadLittleMods added 2 commits May 28, 2026 11:03

satisfied typo

9b3b3da

Fix JSONArraySome logic

f3134ad

See #796 (comment)

anoadragon453 approved these changes May 28, 2026

View reviewed changes

Merge branch 'main' into travis/msc4311-v2

9f339a8

MadLittleMods mentioned this pull request Jul 9, 2026

Fix grammar typo in serverNames arg docstring #890

Merged

1 task

MadLittleMods added 4 commits July 9, 2026 14:57

Fix serverNames arg docstring typo

9500eb0

Fix markdown syntax typo in comment

d9972aa

See #796 (comment)

Fix room plural typo

15d86d1

See #796 (comment)

Clarify why run later "to allow some time for the ecosystem to adapt …

8e23350

…and support MSC4311" See #796 (comment)

MadLittleMods mentioned this pull request Jul 9, 2026

Apply strict MSC4311 stripped state validation after 2027-06-01 element-hq/synapse#19943

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MadLittleMods added 5 commits July 9, 2026 15:21

Cross-link element-hq/synapse#19943

f011b88

Fix other new typos

69c079c

Revert non-new typo

7d525ee

Merge branch 'main' into travis/msc4311-v2

6892bfa

Merge branch 'main' into travis/msc4311-v2

b11afb6

Merge branch 'main' into travis/msc4311-v2

fdd00d2

MadLittleMods merged commit c5c17f6 into main Sep 22, 2026
8 of 10 checks passed

MadLittleMods deleted the travis/msc4311-v2 branch September 22, 2026 17:13

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