升级到 Angular 9 后运行 Jest 测试时出错：TypeError：无法读取未定义的属性“ngModule”

Question

我从 Angular 8.2 升级到 Angular 9。我的项目正在按预期工作，构建也是如此，但是许多测试都因此错误而失败：

TypeError: Cannot read property 'ngModule' of undefined

  at isModuleWithProviders (../packages/core/src/render3/jit/module.ts:530:37)
  at expandModuleWithProviders (../packages/core/src/render3/jit/module.ts:523:7)
      at Array.map (<anonymous>)
  at Function.get (../packages/core/src/render3/jit/module.ts:127:29)
  at getNgModuleDef (../packages/core/src/render3/definition.ts:761:27)
  at isNgModule (../packages/core/src/render3/jit/module.ts:534:12)
  at ../packages/core/src/render3/jit/module.ts:464:10
      at Array.forEach (<anonymous>)
  at transitiveScopesFor (../packages/core/src/render3/jit/module.ts:458:30)
  at setScopeOnDeclaredComponents (../packages/core/src/render3/jit/module.ts:388:28)
  at Object.flushModuleScopingQueueAsMuchAsPossible [as ɵflushModuleScopingQueueAsMuchAsPossible] (../packages/core/src/render3/jit/module.ts:59:11)
  at TestBedRender3.flushModuleScopingQueueAsMuchAsPossible [as checkGlobalCompilationFinished] (../../packages/core/testing/src/r3_test_bed.ts:400:7)
  at TestBedRender3.Object.<anonymous>.TestBedRender3.resetTestingModule (../../packages/core/testing/src/r3_test_bed.ts:231:10)
  at Function.Object.<anonymous>.TestBedRender3.resetTestingModule (../../packages/core/testing/src/r3_test_bed.ts:180:26)
  at ../../packages/core/testing/src/before_each.ts:25:13
  at ZoneDelegate.Object.<anonymous>.ZoneDelegate.invoke (node_modules/zone.js/dist/zone.js:386:30)
  at ProxyZoneSpec.Object.<anonymous>.ProxyZoneSpec.onInvoke (node_modules/zone.js/dist/proxy.js:117:43)
  at ZoneDelegate.Object.<anonymous>.ZoneDelegate.invoke (node_modules/zone.js/dist/zone.js:385:36)
  at Zone.Object.<anonymous>.Zone.run (node_modules/zone.js/dist/zone.js:143:47)

这是一个失败的非常简单的测试的示例：

import { ExampleModule } from './example.module';

describe('ExampleModule', () => {
   let exampleModule: ExampleModule;

  beforeEach(() => {
    exampleModule = new ExampleModule();
  });

  it('should create an instance', () => {
    expect(exampleModule).toBeTruthy();
  });
});

如有任何帮助，我们将不胜感激。谢谢。

Answer 1

就我而言，这是关于我需要在其他模块中导入的组件/模块的导出。所以问题不在于进口，而在于出口。而不是：

export { FirstComponent } from './first.component';
export { FirstModule } from './first.module';

我需要将其导出为：

export * from './first.component';
export * from './first.module';

在 Angular 13 中不再有

TypeError: Cannot read property 'ngModule' of undefined

。

Answer 2

这最终成为桶进口的问题。为了解决这个问题，我必须删除所有桶导入并深度导入所有文件。

旧的例子：

import {
  Example1,
  Example2
} from 'path/to/example-folder';

新示例：

import { Example1 } from 'path/to/example1-file';
import { Example2 } from 'path/to/example2-file';

Answer 3

我也遇到了同样的问题，结果发现根本原因在于循环依赖，根据堆栈跟踪，这不是很直观。解决循环导入解决了这个问题。

Angular 的存储库中有一个原始步骤，其中包含更多详细信息 https://github.com/angular/angular/issues/39573