task(tests): introduce prebuilt mocks and mocking helpers

[bnjbvr]

This introduces new test utilities, starting with MatrixMockServer. This is a pair of a MockServer and a Client (one can retrieve them respectively with .server() and .client()).

It implements a few mock endpoints, expanding and limited the shared code as much as possible, so the mocks are still flexible to use as scoped/unscoped mounts, named, and so on.

It works like this:

• start with telling which endpoint you'd like to mock, e.g. mock_room_send(). This returns a specialized MockSomething data structure, with its own impl. For this example, it's MockRoomSend.
• configure the response on the endpoint-specific mock data structure. For instance, if you want the sending to result in a transient failure, call MockRoomSend::error500(); if you want it to succeed and return the event $42, call MockRoomSend::ok(event_id!("$42")). It's still possible to call respond_with(), as we do with wiremock MockBuilder, for maximum flexibility when the helpers aren't sufficient.
• once the endpoint's response is configured, for any mock builder, you get a MatrixMock; this is a plain wiremock::Mock with the server curried, so one doesn't have to pass it around when calling .mount() or .mount_as_scoped(). As such, it mostly defers its implementations to wiremock::Mock under the hood.

Example

With this, we can go from that code:

#[async_test]
async fn test_make_reply_event_doesnt_require_event_cache() {
    let (client, server) = logged_in_client_with_server().await;

    let event_id = event_id!("$1");
    let resp_event_id = event_id!("$resp");
    let room_id = room_id!("!galette:saucisse.bzh");

    let f = EventFactory::new();

    let raw_original_event = f
        .text_msg("hi")
        .event_id(event_id)
        .sender(client.user_id().unwrap())
        .room(room_id)
        .into_raw_timeline();

    mock_sync_with_new_room(
        |builder| {
            builder.add_joined_room(JoinedRoomBuilder::new(room_id));
        },
        &client,
        &server,
        room_id,
    )
    .await;

    Mock::given(method("GET"))
        .and(path_regex(r"^/_matrix/client/r0/rooms/.*/event/"))
        .and(header("authorization", "Bearer 1234"))
        .respond_with(ResponseTemplate::new(200).set_body_json(raw_original_event.json()))
        .expect(1)
        .named("/event")
        .mount(&server)
        .await;

    let new_content = RoomMessageEventContentWithoutRelation::text_plain("uh i mean bonjour");

    let room = client.get_room(room_id).unwrap();

    // make_edit_event works, even if the event cache hasn't been enabled.
    room.make_edit_event(resp_event_id, EditedContent::RoomMessage(new_content)).await.unwrap();
}

To that code:

#[async_test]
async fn test_make_reply_event_doesnt_require_event_cache() {
    let mock = MatrixMockServer::new().await;
    let user_id = mock.client().user_id().unwrap().to_owned();

    let room_id = room_id!("!galette:saucisse.bzh");
    let room = mock.sync_joined_room(room_id).await;

    let event_id = event_id!("$1");
    let f = EventFactory::new();
    mock.mock_room_event()
        .ok(f.text_msg("hi").event_id(event_id).sender(&user_id).room(room_id).into_timeline())
        .expect(1)
        .named("/event")
        .mount()
        .await;

    let new_content = RoomMessageEventContentWithoutRelation::text_plain("uh i mean bonjour");

    // make_edit_event works, even if the event cache hasn't been enabled.
    room.make_edit_event(event_id, EditedContent::RoomMessage(new_content)).await.unwrap();
}

[codecov]

Codecov Report

Attention: Patch coverage is 94.81481% with 7 lines in your changes missing coverage. Please review.

Project coverage is 84.94%. Comparing base (75683d2) to head (e9016b2).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/matrix-sdk/src/test_utils/mocks.rs	94.69%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4197      +/-   ##
==========================================
+ Coverage   84.88%   84.94%   +0.05%     
==========================================
  Files         272      273       +1     
  Lines       29131    29265     +134     
==========================================
+ Hits        24729    24858     +129     
- Misses       4402     4407       +5     

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[andybalaam]

This is great. Passing on to @richvdh because a) I think he will have helpful feedback and b) I'm not available next week.

[andybalaam]

"mocked server" -> "wiremock server"

[andybalaam]

from_pair -> from_server_and_client or from_parts ?

[andybalaam]

Trying to think of a more informative name for this...

Maybe create_or_change_room ? yuck.

[andybalaam]

I personally have no idea what these methods do, so would be nice to have a comment.

[andybalaam]

I don't understand this. Can you find a different way to write it? I think maybe it's because I don't know much about wiremock.

[richvdh]

some thoughts. Looks like a great improvement.

[richvdh]

I think it would be good to give this a doc-comment explaining its purpose and scope.

Possibly some of the words from your excellent PR description could stand to end up here, as examples.

[richvdh]

come to that, could you add documentation to all of the pub structs being added here?

[richvdh]

is dividing the impl into two bits like this idiomatic? It's confusing for me: I see this and think "hold on, if this is impl MatrixMockServer then what's the other bit?", and repeat a few times to check I'm not missing something.

[richvdh]

Including a client in MatrixMockServer feels a bit awkward to me. WDYT about making the caller responsible for instantiating the client (possibly by having client() instantiate a new Client) and, say, passing a client as an argument into MockSync::ok_and_run ?