toInclude doesn't work with Map object

Description

it('toInclude should work for Maps', () => {
  const obj = { a: 'a', b: 'b', c: 'c' };
  const map = new Map();
  Object.keys(obj).forEach(k => {
    map.set(k, obj[k]);
  });
  expect(map).toInclude({ b: 'b' });
});

Contributor guide

Tech stack

javascript

Domain

testing

Issue type

bug

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

2

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

under 1 hour

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

stale

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

clear

Prerequisites

Basic JavaScriptUnderstanding of Map objects

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

70

Research direction

Investigate the implementation of `toInclude` in the expect library (likely in the main source file). Currently, it only handles plain objects; you need to add support for Map objects by checking if the actual value is a Map and then iterating over its entries to match the expected properties. Review existing tests for `toInclude` to understand the testing patterns and ensure the fix doesn't break existing functionality.