TestBed.overrideModule affects other tests

[kalsowerus]

🐞 bug report

Affected Package

The issue is caused by package @angular/core/testing

Is this a regression?

Yes, the previous version in which this bug was not present was: 8.2.13

Description

All test cases after a call to TestBed.overrideModule seem to be affected by its modifications.

In the provided Example project I have two tests: one.spec.ts and two.spec.ts. Both create an instance of their own component which both contain a TestComponent. In one.spec.ts I replace TestComponent with a Mock using overrideModule. If one.spec.ts is executed first by the test runner, two.spec.ts also uses the Mock component.

Additionally this example also does not work if two.spec.ts is executed first. In that case the overrideModule-call seems to be ignored.

I cannot say for sure wether this is a problem with Angular or Karma. If you think I should open an issue on Karma, please let me know.

🔬 Minimal Reproduction

https://github.com/kalsowerus/repro-app

The TestComponent I mentioned earlier prints 'test' in its ngOnInit(), while the mock component inside one.spec.ts prints 'mock'. To see the problem just npm install and then ng test. The exact command I used to execute the tests is ng test --browsers ChromeForWSL --watch=false. ChromeForWSL being a custom Launcher based on Chrome which disables the "VizDisplayCompositor"-feature since that does not seem to work in a WSL (Windows subsystem for Linux) environment.

The expected result would be seeing both 'test' and 'mock' in the console once in any order. But depending on the execution order either of them are printed twice while the other one is not printed at all.

🔥 Exception or Error

No exception or error

🌍 Your Environment

Angular Version:

Angular CLI: 9.1.1
Node: 12.14.0
OS: linux x64

Angular: 9.1.1
... animations, cli, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router
Ivy Workspace: Yes

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.901.1
@angular-devkit/build-angular     0.901.1
@angular-devkit/build-optimizer   0.901.1
@angular-devkit/build-webpack     0.901.1
@angular-devkit/core              9.1.1
@angular-devkit/schematics        9.1.1
@ngtools/webpack                  9.1.1
@schematics/angular               9.1.1
@schematics/update                0.901.1
rxjs                              6.5.5
typescript                        3.8.3
webpack                           4.42.0

Anything else relevant?

[AndrewKushnir]

Hi @kalsowerus,

Thanks for reporting the issue and providing a repro (this is super helpful!).

I was able to reproduce the problem, will perform further investigation and will keep this thread updated.

Thank you.

[AndrewKushnir]

Hi @kalsowerus,

I've created a PR with proposed fix. I tested the fix using the repro that you provided and it seems to be working correctly now. If you get a chance, it'd be great if you could help test this fix with your real app to see if the original problem is also resolved.

To test your app with the changes from PR #36649, you can follow an instruction in this document on how to use PR artifacts. An archive with updated @angular/core package that contains changes from the PR is available here (please make sure you update other @angular packages to 9.1.2 to avoid version conflicts). Note: the mentioned archive with updated @angular/core package is for testing purposes only and not suitable for production usage (that archive will be removed once PR is closed).

Thank you.

[kalsowerus]

Hi @AndrewKushnir,

Thank you very much for your response. I ran my tests a few times with your PR artifact and could not reproduce the original error. It seems to be working fine now.

Can I expect to see this fix in 9.1.3?

Thank you.

[AndrewKushnir]

Hi @kalsowerus, thanks for your help with testing the change 👍I expect the change to be included into 9.1.3 or 9.1.4 release. Thank you.

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