Support dart2wasm in node.js tests

[simolus3]

Support dart2wasm as a compiler for tests running in Node.js. dart2wasm emits a .mjs file exporting definitions to load generated wasm modules, the only additional thing we have to do is wrap that in a simple entrypoint file compiling the wasm module and invoking the startup wrapper.

There's no support for stack trace maps yet. We also don't support precompiled node wasm tests yet (dart2wasm is also not currently supported by build_web_compilers, so we're blocked on that either way).

In the test runtime, I had to migrate off require as that function is not in the global context for .mjs files. It looks like we can use await import instead though. If we need to support ancient Node versions that lack import support, I can adapt that to still use require when compiled with dart2js for compatibility.

[natebosch]

I'm not worried about supporting old node versions. I think using import should be fine.

My initial reaction was to not want to adopt more complexity for node (which I still hope to separate out to a different package if we find the time for it), but this doesn't look like it will cause extra maintenance burden for us. @jakemac53 do you have any concerns?

[jakemac53]

I am generally comfortable with this, yes.

[simolus3]

Speaking of old node versions, the ubuntu-latest image on GitHub actions ships Node.js version 18 which is too old to support the WebAssembly modules generated by dart2wasm.

I guess we can use actions/setup-node, but I'm not sure if mono_repo allows adding custom actions steps to stages? And that's probably the kind of maintenance burden you were hoping to avoid...

[jakemac53]

I guess we can use actions/setup-node, but I'm not sure if mono_repo allows adding custom actions steps to stages? And that's probably the kind of maintenance burden you were hoping to avoid...

Hmm, yeah I don't think it supports that.

[simolus3]

I have changed the tests to skip dart2wasm if we're running on older node versions. That's not great because it means that this feature is not tested in the CI, but it also means that we won't have to change the CI setup (and at some point ubuntu-latest will ship a recent node version).

[github-actions]

PR Health

Package publish validation ✔️

Package	Version	Status
package:checks	0.3.1-wip	WIP (no publish necessary)
package:test	1.25.9-wip	WIP (no publish necessary)
package:test_api	0.7.4-wip	WIP (no publish necessary)
package:test_core	0.6.6-wip	WIP (no publish necessary)

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.

[natebosch]

I fixed up some of the failing CI jobs. It looks like there are still some legitimate failures.

[Node.js, Dart2Wasm] loading test/hello_world_test.dart (failed)
  Generated wasm module '/tmp/dart_test_WWPNVK/test_KVONWA/hello_world_test.dart.node_test.dart.wasm.wasm', and JS init file '/tmp/dart_test_WWPNVK/test_KVONWA/hello_world_test.dart.node_test.dart.wasm.mjs'.
  node:internal/process/promises:288
              triggerUncaughtException(err, true /* fromPromise */);
              ^
  [CompileError: WebAssembly.compileStreaming(): expected signature definition 0x60, got 0x4e @+13]
  Node.js v[18](https://github.com/dart-lang/test/actions/runs/10523203385/job/29176912922?pr=2259#step:6:21).20.4
  TimeoutException after 0:12:00.000000: Test timed out after 12 minutes.
  package:test_api/src/backend/invoker.dart 338:28  Invoker._handleError.<fn>
  dart:async/zone.dart 1391:47                      _rootRun
  dart:async/zone.dart 1301:[19](https://github.com/dart-lang/test/actions/runs/10523203385/job/29176912922?pr=2259#step:6:22)                      _CustomZone.run
  package:test_api/src/backend/invoker.dart 336:10  Invoker._handleError
  package:test_api/src/backend/invoker.dart 291:9   Invoker.heartbeat.<fn>.<fn>
  dart:async/zone.dart 1399:13                      _rootRun
  dart:async/zone.dart 1301:19                      _CustomZone.run
  package:test_api/src/backend/invoker.dart 290:38  Invoker.heartbeat.<fn>
  dart:async-patch/timer_patch.dart 18:15           Timer._createTimer.<fn>
  dart:isolate-patch/timer_impl.dart 398:19         _Timer._runTimers
  dart:isolate-patch/timer_impl.dart 4[29](https://github.com/dart-lang/test/actions/runs/10523203385/job/29176912922?pr=2259#step:6:32):5          _Timer._handleMessage
  dart:isolate-patch/isolate_patch.dart 184:12      _RawReceivePort._handleMessage

[natebosch]

It also looks like some of the tests are timing out with a really poor UX - the test runner isn't noticing it and the tests are spinning. I'm not sure if thats a new issue, or if it's surfacing an existing issue with some types of timeouts

[simolus3]

It also looks like some of the tests are timing out with a really poor UX - the test runner isn't noticing it and the tests are spinning. I'm not sure if thats a new issue, or if it's surfacing an existing issue with some types of timeouts

This is caused by old Node versions not being able to load the dart2wasm-generated WebAssembly modules. This causes the node process to exit before connecting to the server opened by the test runner. The runner unfortunately waits for a connection, so it didn't detect this condition.
I've changed the implementation to throw an error in that case, which then considers the test failed. I've added a test exercising this behavior to ensure we're not hitting these timeouts on unsupported Node versions, but it also means that we can't run the integration tests in Node on GitHub actions.