isArray.test.ts

import { isArray } from './isArray';
import { typesDataProvider } from '../test/types_data_provider';

describe('isArray', () => {
  test('isArray: should work as type guard', () => {
    const data = typesDataProvider('array');
    if (isArray(data)) {
      expect(Array.isArray(data)).toEqual(true);
      assertType<Array<number>>(data);
    }

    const data1: unknown = typesDataProvider('array');
    if (isArray(data1)) {
      assertType<ReadonlyArray<unknown>>(data1);
    }
  });
  test('isArray: should work as type guard in filter', () => {
    const data = [
      typesDataProvider('error'),
      typesDataProvider('array'),
      typesDataProvider('function'),
      typesDataProvider('null'),
      typesDataProvider('array'),
      typesDataProvider('date'),
    ].filter(isArray);
    expect(data.every(c => Array.isArray(c))).toEqual(true);
    assertType<Array<Array<number>>>(data);
  });
});