Are the Angular tests passing even before the asynchronous call has finished?

Question

Are the Angular tests passing even before the asynchronous call has finished?

When running the following Angular (4) test for a service, it appears to pass before the Observable returns and hits the expect statement.

   it('should enter the assertion', inject(
        [ MockBackend, CellService ],
        ( backend: MockBackend, s: CellService ) => {
            const urls = [];

            backend.connections.subscribe((connection: MockConnection) => {
                const req = connection.request;
                urls.push(req.url);
                if (req.method === RequestMethod.Get && req.url === '/api/getTest') {
                    connection.mockRespond(new Response(new ResponseOptions('enter mocked content')));
                }
            });
            s.getCell('powders').subscribe(val => expect(true).toBeFalsy())
        })
    );

I attempted to use async/await, but it didn't have any effect. What approach should I take here?

Update:

This section of code also passes ...

it('should enter the assertion', async(inject(
    [ MockBackend, CellService ],
    ( backend: MockBackend, s: CellService ) => {
        const urls = [];

        backend.connections.subscribe((connection: MockConnection) => {
            const req = connection.request;
            urls.push(req.url);
            if (req.method === RequestMethod.Get && req.url === '/api/getTest') {
                connection.mockRespond(new Response(new ResponseOptions('enter mocked content')));
            }
        });
        s.getCell('powders').subscribe(val => expect(true).toBeFalsy())
    })
));

angular typescript jasmine

Answer 1

Answer №1

Encase the test within Angular's async

import { async } from '@angular/core/testing';

                         ---==== vvvv ===----
it('should execute the assertion', async(inject(
    [ MockBackend, CellService ],
    ( backend: MockBackend, s: CellService ) => {
        ...
    })
));

This action will envelop the test in a test zone, enabling Angular to effectively wait for all asynchronous tasks to finish before concluding the test.

Additional resources:

Angular 2 Testing - Async function call - when to use
Test a component with an async service
What is the difference between fakeAsync and async in angular2 testing

UPDATE

Experiment with fakeAsycn/tick

import { fakeAsync } from '@angular/core/testing';

it('should enter the assertion', fakeAsync(inject(
    [ MockBackend, CellService ],
    ( backend: MockBackend, s: CellService ) => {
        ...

        let value;
        s.getCell('powders').subscribe(val => {
          value = val;
        })
        tick();
        expect(val).toBeTruthy();
    })
));

While using async should work, opting for fakeAsync can simplify debugging as everything operates synchronously.

If the issue persists, it may be necessary to review the logic elsewhere. One area of concern could be:

req.method === RequestMethod.Get && req.url === '/api/getTest'

Are both conditions met? Failure to pass these checks will result in no response.

Answer 2

Encase the test within Angular's async

import { async } from '@angular/core/testing';

                         ---==== vvvv ===----
it('should execute the assertion', async(inject(
    [ MockBackend, CellService ],
    ( backend: MockBackend, s: CellService ) => {
        ...
    })
));

This action will envelop the test in a test zone, enabling Angular to effectively wait for all asynchronous tasks to finish before concluding the test.

Additional resources:

Angular 2 Testing - Async function call - when to use
Test a component with an async service
What is the difference between fakeAsync and async in angular2 testing

UPDATE

Experiment with fakeAsycn/tick

import { fakeAsync } from '@angular/core/testing';

it('should enter the assertion', fakeAsync(inject(
    [ MockBackend, CellService ],
    ( backend: MockBackend, s: CellService ) => {
        ...

        let value;
        s.getCell('powders').subscribe(val => {
          value = val;
        })
        tick();
        expect(val).toBeTruthy();
    })
));

While using async should work, opting for fakeAsync can simplify debugging as everything operates synchronously.

If the issue persists, it may be necessary to review the logic elsewhere. One area of concern could be:

req.method === RequestMethod.Get && req.url === '/api/getTest'

Are both conditions met? Failure to pass these checks will result in no response.

Answer 3

Answer №2

In this scenario, I personally opt for utilizing the Jasmine done() callback.

To begin with, eliminate injectors in the spec and utilize TestBed.get(serviceToken) within the beforeEach segment.

Next, include done as an argument in the spec function

it('should implement asynchronous functionality', done => {
  s.method().subscribe(result => {
    expect(result).toBe(...);
    done();
  }
})

Answer 4

In this scenario, I personally opt for utilizing the Jasmine done() callback.

To begin with, eliminate injectors in the spec and utilize TestBed.get(serviceToken) within the beforeEach segment.

Next, include done as an argument in the spec function

it('should implement asynchronous functionality', done => {
  s.method().subscribe(result => {
    expect(result).toBe(...);
    done();
  }
})

Answer 5

Answer №3

If you need to handle asynchronous calls in your tests, consider using waitForAsync, designed specifically for this purpose and compatible with both observables and promises.

This function wraps a test function within an asynchronous test zone, allowing the test to automatically complete once all asynchronous operations within that zone have finished. It can be particularly useful when wrapping an inject call. (Link to documentation)

it('...', waitForAsync(inject([AClass], (object) => {
  object.doSomething.subscribe(() => {
    expect(...);
  })
})));

Answer 6

If you need to handle asynchronous calls in your tests, consider using waitForAsync, designed specifically for this purpose and compatible with both observables and promises.

This function wraps a test function within an asynchronous test zone, allowing the test to automatically complete once all asynchronous operations within that zone have finished. It can be particularly useful when wrapping an inject call. (Link to documentation)

it('...', waitForAsync(inject([AClass], (object) => {
  object.doSomething.subscribe(() => {
    expect(...);
  })
})));

Are the Angular tests passing even before the asynchronous call has finished?

Answer №1

UPDATE

Answer №2

Answer №3

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