test(client-presence): Example multi-process E2E test #23305
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scottn12
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Dec 12, 2024
| afterEach(async () => { | ||
| // kill all child processes after each test | ||
| for (const child of children) { | ||
| if (!child.killed) { |
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It would probably make more sense to reset the array after each test. Something like -
let children: ChildProcess[] = [];
afterEach(async () => {
// kill all child processes after each test
for (const child of children) {
child.kill();
}
children = [];
}| if (attendee !== presence.getMyself()) { | ||
| count++; | ||
| attendeesJoined.push(attendee.sessionId); | ||
| if (count === numClients) { |
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nit: You could get rid of count by comparing attendeesJoined.length === numClients instead
| await timeoutPromise( | ||
| (resolve) => { | ||
| let count = 0; | ||
| presence.events.on("attendeeJoined", (attendee) => { |
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Do we need to turn off this listener after we are done with it? I'm not sure if it gets cleaned up automatically
| const waitForDisconnected = children.map(async (child, index) => | ||
| timeoutPromise( | ||
| (resolve) => | ||
| child.on("message", (msg: MessageFromChild) => { |
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Same question as above (re: turning off listeners)
| }; | ||
| }; | ||
|
|
||
| process.on("message", (msg: MessageFromParent) => { |
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Since I commented on the below listeners I just want to note I think we don't need to turn this listener off since the process will get killed
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Not meant to merge
Description
This PR is an example setup of a multi-process end to end test could potentially look like. Each client has their own separate process. There is a client in the parent process who creates the container and child processes that fork from the parent process that get the same container. Through IPC (inter-process communication) calls parent process acts as an orchestrator to its child processes, giving commands about what actions to perform. The child then performs these actions and responds with any information needed to verify correctness. The parent can interact with each child and each child only interacts with the parent.
This was written as an AzureClient E2E test to avoid the complexity of the existing cross-compat in the root e2e test package.
Learnings
This pattern follows something close to the actor model in which the parent process is the only actor that creates other actors. From this experience I realize this concurrent programming model is very different from the traditional single process tests we write now. It would be difficult to integrate this pattern into our current e2e compat test suite. If we build out a new test suite using this actor model for multi-process testing, we'd have to develop new abstractions to make it easy for developers to write tests simply (Actor, Orchestrator, Command/Action, etc.)
Next Steps
We should look into other potential JS frameworks that we could leverage here