Testing a component inside a test host, according to: https://angular.io/guide/testing-components-scenarios#component-inside-a-test-host
Reproduction repo for Issue #39838
ngc throws error (but only when Ivy is enabled):
$ npx ngc
src/app/foobar/foobar.component.spec.ts:12:14 - error NG8001: 'app-foobar' is not a known element:
1. If 'app-foobar' is an Angular component, then verify that it is part of this module.
2. If 'app-foobar' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message.
12 template: `<app-foobar [abc]="'xyz'"></app-foobar>`
~~~~~~~~~~~~~~~~~~~~~~~~~~
src/app/foobar/foobar.component.spec.ts:12:26 - error NG8002: Can't bind to 'abc' since it isn't a known property of 'app-foobar'.
1. If 'app-foobar' is an Angular component and it has 'abc' input, then verify that it is part of this module.
2. If 'app-foobar' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message.
3. To allow any property add 'NO_ERRORS_SCHEMA' to the '@NgModule.schemas' of this component.
12 template: `<app-foobar [abc]="'xyz'"></app-foobar>`
But everything else works just fine (test, build, serve).
Disable Ivy in tsconfig.json, re-run ngc and it will pass successfully.
This project was generated with Angular CLI version 11.0.2.
This problem is also valid for previous Angular 10.
Run npm ci
Before running npx ngc, run npx ngcc
Run ng test to execute the unit tests.
This should pass successfully with or without Ivy. However, ngc fails with Ivy.