Angular 测试角度组件抛出错误失败，类型错误

我已将

CustomError

定义为

export class CustomError extends Error {
    constructor(message?: string) {
        super(message);
        Object.setPrototypeOf(this, CustomError.prototype);
    }
}

我想从角度分量抛出

CustomError

，例如

@Component({
    moduleId: 'module.id',
    templateUrl: 'my.component.html'
})
export class MyComponent {
    someMethod(): void {
        throw new CustomError();
    }
}

现在我想测试是否抛出了

CustomError

，因此我编写了以下测试

describe('MyComponent', () => {

    beforeEach(async(() => {
        TestBed.configureTestingModule({
            declarations: [MyComponent]
        }).compileComponents();
    }));

    beforeEach(async(() => {
        fixture = TestBed.createComponent(MyComponent);
        component = fixture.componentInstance;
    }));

    it('throws CustomError', () => {
        expect(component.someMethod).toThrowError(CustomError);
    });
});

该测试按预期通过。但是，如果我现在将

someProperty

引入

MyComponent

，即

@Component({
    moduleId: 'module.id',
    templateUrl: 'my.component.html'
})
export class MyComponent {
    someProperty: string  = "Why does this break it?";

    someMethod(): void {
        console.log(this.someProperty);  // This breaks it, why?
        throw new CustomError();
    }
}

并尝试在我正在测试的函数中使用该属性（在本例中是写入控制台），我的测试失败，因为抛出了

TypeError

——堆栈跟踪如下：

Expected function to throw AuthError, but it threw TypeError.
        at Object.<anonymous> (webpack:///src/app/auth/login/login.component.spec.ts:46:32 <- config/karma-test-shim.js:68955:33) [ProxyZone]
        at ProxyZoneSpec.onInvoke (webpack:///~/zone.js/dist/proxy.js:79:0 <- config/karma-test-shim.js:65355:39) [ProxyZone]
        at Object.<anonymous> (webpack:///~/zone.js/dist/jasmine-patch.js:104:0 <- config/karma-test-shim.js:65071:34) [ProxyZone]
        at webpack:///~/@angular/core/@angular/core/testing.es5.js:96:0 <- config/karma-test-shim.js:20767:17 [ProxyZone]
        at AsyncTestZoneSpec.onInvoke (webpack:///~/zone.js/dist/async-test.js:49:0 <- config/karma-test-shim.js:64666:39) [ProxyZone]
        at ProxyZoneSpec.onInvoke (webpack:///~/zone.js/dist/proxy.js:76:0 <- config/karma-test-shim.js:65352:39) [ProxyZone]
        at AsyncTestZoneSpec._finishCallback (webpack:///~/@angular/core/@angular/core/testing.es5.js:91:0 <- config/karma-test-shim.js:20762:25) [<root>]
        at webpack:///~/zone.js/dist/async-test.js:38:0 <- config/karma-test-shim.js:64655:31 [<root>]
        at timer (webpack:///~/zone.js/dist/zone.js:1732:0 <- config/karma-test-shim.js:67191:29) [<root>]

期望函数抛出AuthError，但它抛出了TypeError。
反对。(webpack:///src/app/auth/login/login.component.spec.ts:46:32 您丢失了上下文
此

getJasmineRequireObj().toThrowError = function(j$) {
  function toThrowError () {
    return {
      compare: function(actual) {
        var threw = false,
          pass = {pass: true},
          fail = {pass: false},
          thrown;

        if (typeof actual != 'function') {
          throw new Error('Actual is not a Function');
        }

        var errorMatcher = getMatcher.apply(null, arguments);

        try {
          actual(); // call function reference component.someMethod

我会写

expect(component.someMethod.bind(component)).toThrowError(CustomError);

您丢失了上下文
此

getJasmineRequireObj().toThrowError = function(j$) {
  function toThrowError () {
    return {
      compare: function(actual) {
        var threw = false,
          pass = {pass: true},
          fail = {pass: false},
          thrown;

        if (typeof actual != 'function') {
          throw new Error('Actual is not a Function');
        }

        var errorMatcher = getMatcher.apply(null, arguments);

        try {
          actual(); // call function reference component.someMethod

我会写

expect(component.someMethod.bind(component)).toThrowError(CustomError);

不应该是
console.log（this.someProperty）
？@adiga是的，那是一个错误。测试仍然失败。不应该是
console.log（this.someProperty）
？@adiga是的，那是一个错误。测试仍然失败。