@theia/core/src/common/promise-util.spec.ts

Theia is a cloud & desktop IDE framework implemented in TypeScript.

// *****************************************************************************
// Copyright (C) 2021 Red Hat and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// http://www.eclipse.org/legal/epl-2.0.
//
// This Source Code may also be made available under the following Secondary
// Licenses when the conditions for such availability set forth in the Eclipse
// Public License v. 2.0 are satisfied: GNU General Public License, version 2
// with the GNU Classpath Exception which is available at
// https://www.gnu.org/software/classpath/license.html.
//
// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0
// *****************************************************************************
import * as assert from 'assert/strict';
import { firstTrue, waitForEvent } from './promise-util';
import { Emitter } from './event';
import { CancellationError } from './cancellation';

describe('promise-util', () => {

    describe('waitForEvent', () => {
        it('should time out', async () => {
            const emitter = new Emitter<string>();
            await assert.rejects(waitForEvent(emitter.event, 1000), reason => reason instanceof CancellationError);
        });

        it('should get event', async () => {
            const emitter = new Emitter<string>();
            setTimeout(() => {
                emitter.fire('abcd');
            }, 500);
            assert.strictEqual(await waitForEvent(emitter.event, 1000), 'abcd');
        });
    });

    describe('firstTrue', () => {
        it('should resolve to false when the promises arg is empty', async () => {
            const actual = await firstTrue();
            assert.strictEqual(actual, false);
        });

        it('should resolve to true when the first promise resolves to true', async () => {
            const signals: string[] = [];
            const createPromise = (signal: string, timeout: number, result: boolean) =>
                new Promise<boolean>(resolve => setTimeout(() => {
                    signals.push(signal);
                    resolve(result);
                }, timeout));
            const actual = await firstTrue(
                createPromise('a', 10, false),
                createPromise('b', 20, false),
                createPromise('c', 30, true),
                createPromise('d', 40, false),
                createPromise('e', 50, true)
            );
            assert.strictEqual(actual, true);
            assert.deepStrictEqual(signals, ['a', 'b', 'c']);
        });

        it('should reject when one of the promises rejects', async () => {
            await assert.rejects(firstTrue(
                new Promise<boolean>(resolve => setTimeout(() => resolve(false), 10)),
                new Promise<boolean>(resolve => setTimeout(() => resolve(false), 20)),
                new Promise<boolean>((_, reject) => setTimeout(() => reject(new Error('my test error')), 30)),
                new Promise<boolean>(resolve => setTimeout(() => resolve(true), 40)),
            ), /Error: my test error/);
        });
    });

});