ladygrey

npm install ladygrey --save-dev

Due to the asynchronous nature of promises, testing them in standard unit tests (e.g. Mocha test cases) can be difficult. This is especially the case when a promise is tested with mock objects. For example, how should the test case know when to verify the mock's expectations when it doesn't know exactly when the promise will be resolved?

ladygrey defines the PromiseExpectation class, which provides a number of promise testing utilities, built on top of Chai, to make testing promises easier.

Example:

function foo() {
    return new Promise(function(resolve, reject) {
        resolve(5);
    });
}

describe("foo", function() {
    it("should resolve and return 5", function() {
        var promiseToTest = foo();
        return ladygrey.expect(promiseToTest)
                       .shouldResolveWith(5)
                       .run();
    });
});

Features

ladygrey.PromiseExpectation concisely sets expectations on whether promises being tested should resolve or reject, what's passed to the resolve/reject function and verify other expected side-effects after the promise has been executed.

ladygrey.PromiseExpectation currently supports the following features:

• setting expectation on result of promise (resolve or reject)
• setting expectations on what's passed to resolve/reject function
• verifying sinon-style mocks the promise used (ensuring the verification is executed after the promise has finished executing
• verifying ladygrey.MockPromises used by promise under test were settled (called)

ladygrey.MockPromise is an additional utility that constructs a promise-like object which resolves/rejects with the arguments you specify, which is useful when testing code that uses nested promises. This is why ladygrey.PromiseExpectation supports verification of MockPromisess -- it allows promises which call other promises to be tested in isolation.

Tests

Execute ladygrey's unit tests and example tests by running npm test.

Basic Usage Example

See examples/basic_example.js for a basic example on how to use ladygrey to test promises. This example also shows how ladygrey.MockPromise can be used to create isolated tests when nested promises are used.

Detailed Usage Guide

TODO: more detailed usage guide with examples here