kefir-test-utils

import * as Kefir from 'kefir'; import { withTime, watch } from 'kefir-test-utils'; describe('Kefir-test-utils example', () => { it('should test a simple observable with virtual time', () => { withTime((tick) => { // Create a Kefir stream that emits 1, 2, 3 sequentially with 100ms intervals const stream = Kefir.sequentially(100, [1, 2, 3]); // Use `watch` to collect events from the stream const watcher = watch(stream); // Assert initial state expect(watcher.next).toEqual([]); // Advance virtual time tick(50); // 50ms passed expect(watcher.next).toEqual([]); // No emissions yet tick(50); // Total 100ms passed expect(watcher.next).toEqual([1]); // First emission received tick(100); // Total 200ms passed expect(watcher.next).toEqual([1, 2]); // Second emission received tick(100); // Total 300ms passed expect(watcher.next).toEqual([1, 2, 3]); // All emissions received expect(watcher.complete).toEqual(true); // Stream completed }); }); it('should handle errors in a stream gracefully', () => { withTime((tick) => { // Create a stream that emits 1, then an error, which is caught and mapped to a message const errorStream = Kefir.sequentially(50, [1]) .concat(Kefir.later(50, new Error('Simulated Error'))) .flatMapErrors(e => Kefir.constant(e.message)); // Catch error and emit message const watcher = watch(errorStream); tick(50); expect(watcher.next).toEqual([1]); tick(50); // The error was caught and its message was emitted as a 'next' event expect(watcher.next).toEqual([1, 'Simulated Error']); expect(watcher.error).toEqual([]); // No actual error was propagated by `flatMapErrors` expect(watcher.complete).toEqual(true); }); }); });