type-fns/dist/checks/isAPromise.test.js

A set of types, type checks, and type guards for simpler, safer, and easier to read code.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
const isAPromise_1 = require("./isAPromise");
describe('isAPromise', () => {
    it('should return true for promises', () => {
        const descision = (0, isAPromise_1.isAPromise)(Promise.resolve('hello'));
        expect(descision).toEqual(true);
    });
    it('should return false for not promises', () => {
        const descision = (0, isAPromise_1.isAPromise)('hello');
        expect(descision).toEqual(false);
    });
    it('should be usable to narrow the typescript type', () => {
        // imagine we didn't know whether soonerOrLater is a promise or a string
        const soonerOrLater = Promise.resolve('hello');
        // we can use this check to narrow down the typescript type and do operations specific to each type
        if ((0, isAPromise_1.isAPromise)(soonerOrLater)) {
            void soonerOrLater.then(() => 'done');
        }
        else {
            void soonerOrLater.toLowerCase();
        }
    });
});
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