core-js/tests/unit-global/es.array.find-index.js

import { STRICT } from '../helpers/constants.js';

QUnit.test('Array#findIndex', assert => {
  const { findIndex } = Array.prototype;
  assert.isFunction(findIndex);
  assert.arity(findIndex, 1);
  assert.name(findIndex, 'findIndex');
  assert.looksNative(findIndex);
  assert.nonEnumerable(Array.prototype, 'findIndex');
  const array = [1];
  const context = {};
  array.findIndex(function (value, key, that) {
    assert.same(arguments.length, 3, 'correct number of callback arguments');
    assert.same(value, 1, 'correct value in callback');
    assert.same(key, 0, 'correct index in callback');
    assert.same(that, array, 'correct link to array in callback');
    assert.same(this, context, 'correct callback context');
  }, context);
  // eslint-disable-next-line unicorn/prefer-array-index-of -- ignore
  assert.same([1, 3, NaN, 42, {}].findIndex(it => it === 42), 3);
  // eslint-disable-next-line unicorn/prefer-array-index-of -- ignore
  assert.same([1, 3, NaN, 42, {}].findIndex(it => it === 43), -1);
  if (STRICT) {
    assert.throws(() => findIndex.call(null, 0), TypeError);
    assert.throws(() => findIndex.call(undefined, 0), TypeError);
  }
  assert.notThrows(() => findIndex.call({
    length: -1,
    0: 1,
  }, () => {
    throw new Error();
  }) === -1, 'uses ToLength');
  assert.true('findIndex' in Array.prototype[Symbol.unscopables], 'In Array#@@unscopables');
});