Node / Mocha / Chai / Sinon-异步等待单元测试错误

Question

I 'm experimenting with async await / sinon, but getting a weird error, here is what I have:

billing.js

exports.getUnbilledChargesSummary = async(function (callback) {
    try {
        var retailerList = await(exports.getBillableRetailerList());
        var chargesList = await(exports.getAllUnbilledChargesSums());
        var result = exports.assignUnbilledChargesSumForEachRetailer(retailerList, chargesList);
        return callback(null, result);
    }
    catch (ex) {
        console.error('Exception in getUnbillecChargesSummary');
        console.error(ex)
        return callback(ex);
    }
});

billing.test.js

describe('billing', () => {
    const retailers = [{ id: 111, common_name: 'Retailer 1' }, { id: 222, common_name: 'Retailer 2' }, { id: 333, common_name: 'Retailer 3' }];
    const charges = [{ retailer_id: 111, sum: 100 }, { retailer_id: 222, sum: 200 }];

    it('should get summary of all unbilled charges for each retailer', (done) => {
        var getBillableRetailerListStub = sinon.stub(billing, 'getBillableRetailerList').returns(Promise.resolve(retailers));
        var getAllUnbilledChargesSumsStub = sinon.stub(billing, 'getAllUnbilledChargesSums').returns(Promise.resolve(charges));

        billing.getUnbilledChargesSummary((err, result) => {
            console.log('result', result);
            expect(result).to.deep.include({ id: 111, common_name: 'Retailer 1', sum: 100 });
            expect(result).to.deep.include({ id: 222, common_name: 'Retailer 2', sum: 200 });
            expect(result).to.deep.include({ id: 333, common_name: 'Retailer 3', sum: 10 });
            done();
        });
    });
});

It seems that the catch in my function is catching the error for expect, here is the output:

    billing
result [ { id: 111, common_name: 'Retailer 1', sum: 100 },
  { id: 222, common_name: 'Retailer 2', sum: 200 },
  { id: 333, common_name: 'Retailer 3', sum: 0 } ]
Exception in getUnbillecChargesSummary
{ AssertionError: expected [ Array(3) ] to deep include { id: 333, common_name: 'Retailer 3', sum: 10 }
    at billing.getUnbilledChargesSummary (/Users/User/work/billing_api/services/billing.test.js:19:36)
    at Object.<anonymous> (/Users/User/work/billing_api/services/billing.js:58:16)
    at tryBlock (/Users/User/work/billing_api/node_modules/asyncawait/src/async/fiberManager.js:39:33)
    at runInFiber (/Users/User/work/billing_api/node_modules/asyncawait/src/async/fiberManager.js:26:9)
  message: 'expected [ Array(3) ] to deep include { id: 333, common_name: \'Retailer 3\', sum: 10 }',
  showDiff: false,
  actual:
   [ { id: 111, common_name: 'Retailer 1', sum: 100 },
     { id: 222, common_name: 'Retailer 2', sum: 200 },
     { id: 333, common_name: 'Retailer 3', sum: 0 } ],
  expected: undefined }
result undefined
Unhandled rejection AssertionError: Target cannot be null or undefined.
    at billing.getUnbilledChargesSummary (/Users/User/work/billing_api/services/billing.test.js:17:36)
    at Object.<anonymous> (/Users/User/work/billing_api/services/billing.js:63:16)
    at tryBlock (/Users/User/work/billing_api/node_modules/asyncawait/src/async/fiberManager.js:39:33)
    at runInFiber (/Users/User/work/billing_api/node_modules/asyncawait/src/async/fiberManager.js:26:9)

    1) should get summary of all unblled charges for each retailer
    - should get list of all billable retailers
    - should get sum for each unbilled retailer in retailer bill charges


  0 passing (2s)
  5 pending
  1 failing

  1) billing should get summary of all unbilled charges for each retailer:
     Error: Timeout of 2000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves.

If I don't check the failure expect (last item, retailer3 with sum of 10), the code works without problems, if I remove the catch in my function (which I can't really do in live code anyways), mocha doesn't seem to call done() still.

Answer 1

You shouldn't mix callbacks and async/await , exports.getUnbilledChargesSummary returns a promise, even with passed callback.

To get result of async function in calling function, you can use async/await or promise chain:

exports.getUnbilledChargesSummary = async () => {
    try {
        var retailerList = await(exports.getBillableRetailerList());
        var chargesList = await(exports.getAllUnbilledChargesSums());
        return exports.assignUnbilledChargesSumForEachRetailer(retailerList, chargesList);
    } catch (err) {
        console.error('Exception in getUnbillecChargesSummary');
        console.error(err);
        throw err;
    }
};

For testing async functions in Mocha, you can need to call callback done or return a promise. So as getBillableRetailerList and getAllUnbilledChargesSums are async functions too, you should use resolves , not returns callback in sinon.stub.

describe('billing', () => {
    const retailers = [{ id: 111, common_name: 'Retailer 1' }, { id: 222, common_name: 'Retailer 2' }, { id: 333, common_name: 'Retailer 3' }];
    const charges = [{ retailer_id: 111, sum: 100 }, { retailer_id: 222, sum: 200 }];

    it('should get summary of all unbilled charges for each retailer', async () => {
        let getBillableRetailerListStub = sinon.stub(billing, 'getBillableRetailerList').resolves(retailers);
        let getAllUnbilledChargesSumsStub = sinon.stub(billing, 'getAllUnbilledChargesSums').resolves(charges);

        let result = await billing.getUnbilledChargesSummary();
        expect(result).to.deep.include({ id: 111, common_name: 'Retailer 1', sum: 100 });
        expect(result).to.deep.include({ id: 222, common_name: 'Retailer 2', sum: 200 });
        expect(result).to.deep.include({ id: 333, common_name: 'Retailer 3', sum: 10 });
    });
});