bug(HarnessLoader): Unit tests fail when the harness loader is created in beforeEach

[TrevorKarjanis]

Reproduction

The unit tests fail when the harness loader is created in an async beforeEach and the TS target is ES2018.
StackBlitz Demo

There are three solutions to this problem.

1. Move the call to TestbedHarnessEnvironment.loader to the it function (demo).
2. Use waitForAsync in the beforeEach instead of an async function (demo).
3. Change the target to ES2016 (demo).

Steps to reproduce:

1. Create a unit test describe block that includes the harness loader.
2. Assign the harness loader in the beforeEach function.
3. Get a harness with await loader.getHander in an async it function.

Expected Behavior

I'd expect the test to pass, because it is setup as described in component harness documentation and ES2018 is the generated default target.

Actual Behavior

TestbedHarnessEnvironment.loader returns undefined in the beforeEach, and the test fails with the following.

Error: Expected to be running in 'ProxyZone', but it was not found.
    at Function.ProxyZoneSpec.assertPresent (https://harness-issue-hsdvet.stackblitz.io/turbo_modules/zone.js@0.11.3/dist/proxy.js:39:23)
    at Function.TaskStateZoneInterceptor.setup (https://harness-issue-hsdvet.stackblitz.io/turbo_modules/@angular/cdk@11.0.4/bundles/cdk-testing-testbed.umd.js:354:42)
    at new TestbedHarnessEnvironment (https://harness-issue-hsdvet.stackblitz.io/turbo_modules/@angular/cdk@11.0.4/bundles/cdk-testing-testbed.umd.js:1167:57)
    at Function.TestbedHarnessEnvironment.loader (https://harness-issue-hsdvet.stackblitz.io/turbo_modules/@angular/cdk@11.0.4/bundles/cdk-testing-testbed.umd.js:1177:20)
    at UserContext.eval (https://harness-issue-hsdvet.stackblitz.io/~/src/app/button-harness-example.spec.ts:21:54)
TypeError: Cannot read property 'getHarness' of undefined
    at UserContext.eval (https://harness-issue-hsdvet.stackblitz.io/~/src/app/button-harness-example.spec.ts:24:37)
    at ZoneDelegate.invoke (https://harness-issue-hsdvet.stackblitz.io/turbo_modules/zone.js@0.11.3/dist/zone.js:395:30)
    at ProxyZoneSpec.onInvoke (https://harness-issue-hsdvet.stackblitz.io/turbo_modules/zone.js@0.11.3/dist/proxy.js:125:43)
    at ZoneDelegate.invoke (https://harness-issue-hsdvet.stackblitz.io/turbo_modules/zone.js@0.11.3/dist/zone.js:394:56)
    at Zone.run (https://harness-issue-hsdvet.stackblitz.io/turbo_modules/zone.js@0.11.3/dist/zone.js:155:47)
    at runInTestZone (https://harness-issue-hsdvet.stackblitz.io/turbo_modules/zone.js@0.11.3/dist/jasmine-patch.js:203:38)
    at UserContext.eval (https://harness-issue-hsdvet.stackblitz.io/turbo_modules/zone.js@0.11.3/dist/jasmine-patch.js:218:24)
    at <Jasmine>

Environment

• Angular: 11.0.9
• CDK/Material: 11.0.4
• Browser(s): Chrome 87.0.4280.141
• Operating System (e.g. Windows, macOS, Ubuntu): macOS 11.1

[jelbourn]

Angular does not actually work with any ES2017 or later output. This is because zone.js cannot patch the native async and await syntax. You can follow the canonical issue for this here: angular/angular#31730. Resolving this is on Angular's roadmap.

[TrevorKarjanis]

@jelbourn This might not be the place, but I'd like to selfishly leave a quick piece of feedback. Supporting async/await in testing is awesome! However, I would have expected support for ES next with an option for async/await from your roadmap rather than a blanket drop in support for the whole standard. I don't even use async/await in my application code, because it doesn't support the component lifecycle. That is critical given the types of applications I build, and I find the advantages of CD and RxJS outweigh async/await. I hope the framework continues to progress beyond the standards in those respects after Zone becomes optional. I've been targeting ES2018 for some time, lol.

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