utils.js

import expect from 'expect';

export function consoleMockWrapper(cb) {
    const log = expect.spyOn(console, 'log');
    const error = expect.spyOn(console, 'error');

    const completed = (err) => {
        log.calls = [];
        log.restore();

        error.calls = [];
        error.restore();

        if (err) {
            throw err;
        }
    };

    return Promise.resolve(cb(log, error))
        .then(() => completed())
        .catch(completed);
}

export function makeGetterSpy(obj, getter) {
    let callCount = 0;

    // store reference to old getter for restore
    const oldGetter = obj.__lookupGetter__(getter);

    if (!oldGetter) {
        throw new Error('Attempted to add getter spy to unsupported attribute');
    }

    // define spy getter
    Object.defineProperty(obj, getter, {
        get() {
            callCount++;
            return oldGetter.call(obj);
        },
        configurable: true,
    });

    return {
        called() {
            return callCount > 0;
        },
        callCount() {
            return callCount;
        },
        restore() {
            Object.defineProperty(obj, getter, {
                get: oldGetter,
                configurable: true,
            });
        },
    };
}