Property 'jasmineMatches' is missing in type 'x'

问题

After ng test

Expected output: i get pass/fail on x amount of tests.

Actual ouput:

ERROR in src/app/todo-data.service.spec.ts(19,45): error TS2345: Argument of type 'Todo[]' is not assignable to parameter of type 'Expected<Observable<Todo[]>>'.
  Type 'Todo[]' is not assignable to type 'ObjectContaining<Observable<Todo[]>>'.
    Property 'jasmineMatches' is missing in type 'Todo[]'.

In my todo class i don't have a jasminematches property, but this might not be the root problem.

todo.ts:

export class Todo {
  id: number;
  title: string = '';
  complete: boolean = false;

  constructor(values: Object = {}) {
    Object.assign(this, values);
  }
}

todo-data.service.spec.ts

import {TestBed, async, inject} from '@angular/core/testing';
import {Todo} from './todo';
import {TodoDataService} from './todo-data.service';

...

  describe('#getAllTodos()', () => {

    it('should return an empty array by default', inject([TodoDataService],
      (service: TodoDataService) => {
      expect(service.getAllTodos()).toEqual(<Todo[]>[]);
    }));

...

todo-data.service.ts

import { Injectable } from '@angular/core';
import { Todo } from './todo';
import { ApiService } from './api.service';
import { Observable } from 'rxjs';

...

export class TodoDataService {

  constructor(private api: ApiService) { }

  getAllTodos(): Observable<Todo[]> {
    return this.api.getAllTodos();
  }

...

Please advise how to start deconstructing this error in order to write a correct test.

回答1:

Your getAllTodos function returns an observable and not an array of todos. I think this is why an error occurs. Therefore I think you should write your test differently:

service.getAllTodos().subscribe(todos => {
  expect(todos).toEqual([])
});

Also (if you haven't already) you probably want to provide a a stub (mock) for your api service. You should test this service in it's own file.

In your testfile below describe but before you make your testBed (or in a separate file from which you can import it):

const dummyTodos = [];

const mockApiService = {
  getAllTodos() {
    return Observable.of(dummyTodos);
  }
};

In your TestBed.configureTestingModule add the line:

providers: [{provide: ApiService, useValue: mockApiService}],

You can also decide to change the value of the dummyTodos in your tests to check for different responses.

回答2:

I came to the same conclusion of the previous poster. Your initial test assertion is comparing a pending Http request (represented as an observable stream with a single observable) to the expected response of an empty `Todo[]' array.

In the code snippet below, the .subscribe method activates the observable stream. Placing it inside of a fakeAsync zone simulates the passage of time in the same way that an asynchronous Http request behaves. Since the test assertion is inside the subscribe block, you are now dealing with a completed observable stream and are able to access the contents of the stream, i.e., Todo[].

it('should return an empty array by default', fakseAsync(inject([TodoDataService],
  (service: TodoDataService) => {
      service.getAllTodos().subscribe(success => {
        expect(success).toEqual(<Todo[]>)
      });
  ))
);

One behavior in your test that I don't quite understand is your TodoService appears to delegate Http handling to an ApiService that returns Observable<Todo[]> and your TodoService also returns Observable<Todo[]>. If there's a meaningful layer of abstraction between these two services, then I'd defer to the testing method with a MockApiService outlined in the initial answer.

Alternatively, you could collapse your ApiService and TodoService into a single level and make additional assertions about the expected behavior (the mechanics of testing/simulating the Http backend will depend on whether you are using the Http methods in @angular/http or @angular/common/http).

来源：https://stackoverflow.com/questions/50678582/property-jasminematches-is-missing-in-type-x