TestBed passes even without any declarations in NG9 and NG10

🐞 bug report

Affected Package

The issue seems to be in @angular/core/testing or the new bazel/ivy build rig.

Is this a regression?

Yes, this behavior worked in Angular 8. Angular 8 reports the following error…

Error: Illegal state: Could not load the summary for directive AppComponent.
error properties: Object({ ngSyntaxError: true })

Description

Angular’s TestBed no longer works in any kind of logical way.

You can completely remove calls to TestBed.configureTestingModule and the unit tests still run, compile, and succeed. This is totally unexpected, as you are supposed to be able to pass declarations or mock declarations for every token. It’s now completely unclear what environment is being used when the test runs, whereas before you explicitly provided every dependency.

🔬 Minimal Reproduction

https://github.com/smzelek/minimal-repro-ng10-testbed-bug Simply run the unit tests:

1. npm run test

Notice that all 3 tests pass, the component is successfully rendered in the Karma runner window, variable templating succeeds…, even though there is no TestBed configuration at all.

🌍 Your Environment

Angular Version:

     _                      _                 ____ _     ___ 
    / \   _ __   __ _ _   _| | __ _ _ __     / ___| |   |_ _|
   / △ \ | '_ \ / _` | | | | |/ _` | '__|   | |   | |    | | 
  / ___ \| | | | (_| | |_| | | (_| | |      | |___| |___ | | 
 /_/   \_\_| |_|\__, |\__,_|_|\__,_|_|       \____|_____|___|
                |___/
    

Angular CLI: 10.0.7
Node: 12.18.2
OS: win32 x64

Angular: 10.0.12
... animations, common, compiler, compiler-cli, core, forms
... platform-browser, platform-browser-dynamic, router
Ivy Workspace: Yes

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.1000.7
@angular-devkit/build-angular     0.1000.7
@angular-devkit/build-optimizer   0.1000.7
@angular-devkit/build-webpack     0.1000.7
@angular-devkit/core              10.0.7
@angular-devkit/schematics        10.0.7
@angular/cli                      10.0.7
@ngtools/webpack                  10.0.7
@schematics/angular               10.0.7
@schematics/update                0.1000.7
rxjs                              6.5.5
typescript                        3.9.7
webpack                           4.43.0

[AndrewKushnir]

Hi @ahnpnl,

Components might be pre-compiled (in AOT mode) before tests are executed by TestBed, in which case TestBed uses compiled components and only re-compile them (in JIT mode) when there is an override which can not be applied as a patch (i.e. without triggering a re-compilation), for example if a template is overwritten in a test. In View Engine’s version of TestBed components were always re-compiled for each set of tests.

Looking at the issue that you refer to (thymikee/jest-preset-angular#409), I think it might make sense to open a new ticket and describe questions/issues that you have, so that the team can provide some additional insights.

Thank you.

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