blue-tape

const test = require('blue-tape'); // Simulate an async operation that resolves function delay(ms) { return new Promise(resolve => setTimeout(resolve, ms, 'success')); } // Simulate an async operation that rejects function failDelay(ms = 1) { return new Promise((resolve, reject) => { setTimeout(() => reject(new Error('Failed on purpose!')), ms); }); } // Custom error type for specific rejection testing class DerpError extends Error { constructor(message) { super(message); this.name = 'DerpError'; } } function failWithDerpError(ms = 1) { return new Promise((resolve, reject) => { setTimeout(() => reject(new DerpError('Oh snap!')), ms); }); } test("simple delay - promise resolves, test ends", async function(t) { const result = await delay(1); t.equal(result, 'success', 'delay should resolve with success'); // No t.plan() or t.end() needed when returning a promise }); test("should fail - promise chain throws error, test fails", async function(t) { try { await delay(1).then(function() { throw new Error("This promise chain should cause a test failure!"); }); t.fail('Should have thrown an error'); } catch (e) { t.ok(e instanceof Error, 'Error should be caught'); t.equal(e.message, 'This promise chain should cause a test failure!', 'Correct error message'); } }); test("promise fails but test succeeds using t.shouldFail", async function(t) { // t.shouldFail returns a promise that resolves if the input promise rejects await t.shouldFail(failDelay(), /Failed on purpose!/); t.pass('Promise rejected as expected'); }); test("promise fails with specific error type using t.shouldFail", async function(t) { await t.shouldFail(failWithDerpError(), DerpError); t.pass('Promise rejected with DerpError as expected'); });