#jest/prefer-to-contain

#Configuration

import { defineConfig, jestPlugin } from '@rslint/core';

export default defineConfig([
  jestPlugin.configs.recommended,
  {
    rules: {
      'jest/prefer-to-contain': 'error',
    },
  },
]);

#Rule Details

In order to have a better failure message, toContain() should be used upon asserting expectations on an array containing an object.

This rule triggers a warning if toBe(), toEqual() or toStrictEqual() is used to assert object inclusion in an array.

Examples of incorrect code for this rule:

expect(a.includes(b)).toBe(true);
expect(a.includes(b)).not.toBe(true);
expect(a.includes(b)).toBe(false);
expect(a.includes(b)).toEqual(true);
expect(a.includes(b)).toStrictEqual(true);

Examples of correct code for this rule:

expect(a).toContain(b);
expect(a).not.toContain(b);

#Original Documentation

• jest/prefer-to-contain