[BUG] API Assertion 'toContainEqual' fails given one/all correct json key-value pair

[carlnoval]

Context:

• Playwright Version: Version 1.30.0
• Operating System: MacOS Ventura Version 13.2 with M1(2020)
• Node.js version: v16.13.1
• Browser: Chromium 110.0.5481.38, FireFox 108.0.2, WebKit 16.4

Code Snippet

test('unable to fetch an invalid movie', async ({ request, _tmdbV3API, _tmdbV3APIKey }) => {
  // const requestURL = 'https://api.themoviedb.org/3/movie/315162?api_key='
  const invalidID = '9999999999'
  const requestURL = `${_tmdbV3API}movie/${invalidID}?api_key=${_tmdbV3APIKey}` ;
  const movie = await request.get(requestURL);
  expect(movie.status()).toBe(404);
  expect(await movie.json()).toContainEqual(expect.objectContaining({
    status_code: 34,
    status_message: "The resource you requested could not be found.",
    success: false
  }));
});

Error

Error: expect(received).toContainEqual(expected) // deep equality

Expected value:  ObjectContaining {"status_code": 34, "status_message": "The resource you requested could not be found.", "success": false}
Received object: {"status_code": 34, "status_message": "The resource you requested could not be found.", "success": false}

  26 |     const movie = await request.get(requestURL);
  27 |     expect(movie.status()).toBe(404);
> 28 |     expect(await movie.json()).toContainEqual(expect.objectContaining({
     |                                ^
  29 |       status_code: 34,
  30 |       status_message: "The resource you requested could not be found.",
  31 |       success: false

Describe the bug

• Expected Result: API assertion should pass given one/all correct json key-value pairs inside expect.objectContaining.
• Actual Result: API assertion fails given one/all correct json key-value pairs used inside expect.objectContaining.
• More info:
  • The final assertion uses techniques from the official doc where .toContainEqual(expect.objectContaining is used.
  • One discord user suggested to use .toEqual instead of toContainEqual. Using .toEqual makes the API assertion pass given one/all correct json key-value pair.
• Descriptions: .toEqual vs toContainEqual
  • .toEqual - Used when you want to check that two objects have the same value. This matcher recursively checks the equality of all fields, rather than checking for object identity.
  • toContainEqual - Used when you want to check that an item is in a list. For testing the items in the list, this matcher recursively checks the equality of all fields, rather than checking for object identity.

Query

1. Should the doc be updated to use .toEqual instead of toContainEqual?

[aslushnikov]

@carlnoval can you please provide me with the actual value of the movie.json() so that I can try running this locally?

[carlnoval]

const movieJson = await movie.json();
console.log(movieJson);

@aslushnikov Above code generates below json.

{
  success: false,
  status_code: 34,
  status_message: 'The resource you requested could not be found.'
}

[aslushnikov]

@carlnoval your movieJson is not an array; the method toContainEqual expects it to be an array:

Use .toContainEqual when you want to check that an item with a specific structure and values is contained in an array.

So, for example, the following works fine for me:

import { test, expect } from '@playwright/test';

test('should work', async ({ }) => {
  const array = [{
    success: false,
    status_code: 34,
    status_message: 'The resource you requested could not be found.'
  }];
  expect(array).toContainEqual(expect.objectContaining({
    status_code: 34,
    status_message: "The resource you requested could not be found.",
    success: false
  }));
});

Should the doc be updated to use .toEqual instead of toContainEqual?

In the doc, we actually pull issues - which is an array, so it toContainEqual is a proper use there.

Hope this helps!

[carlnoval]

@aslushnikov Got it! Was thinking that await issues.json() from the doc resolves to a json.

Thanks!