How can I test through a mocked promise with Mocha? - node.js

Question

My node.js code is:
function getPatientNotificationNumbers(patientId) {
patientId = patientId && patientId.toString();
var sql = "SELECT * FROM [notification_phone_number] ";
sql += "WHERE patient_id = " + escapeSql(patientId);
return sqlServer.query(sql).then(function(results) {
var phoneNumbers = _.map(results[0], function (result) {
var obj = {
id: result.id,
phoneNumber: result.phone_number,
isPrimary: result.is_primary,
isVerified: result.is_verified,
patientId: result.patient_id
}
return obj;
});
return phoneNumbers;
});
}
Pretty simple and straight forward. What I want to test is that the return of this function, properly resolved, is an array of phoneNumbers that match that format.
sqlServer is require'd above and I have a ton of things require'd in this file. To stub them out, I am using mockery, which seems to be pretty great.
Here is my test, so far:
before(function() {
deferred = Q.defer();
mockery.enable();
moduleConfig.init();
mockery.registerSubstitute('moment', moment);
mockery.registerAllowable('../../util');
mockStubs.sqlServer = {
query: sinon.stub().returns(deferred.promise)
}
mockery.registerMock('../../db/sqlserver', mockStubs.sqlServer);
methods = require('../../../rpc/patient/methods');
});
beforeEach(function() {
deferred = Q.defer();
})
it('should get the patient notification numbers', function(done) {
// sinon.spy(sqlServer, 'query').and.returnValue(deferred.promise);
deferred.resolve('here we go');
methods.getPatientNotificationNumbers(1).then(function(result) {
console.log(result);
done();
});
});
However, it never gets past sqlServer.query in my code. So the results are pointless. I also tried something like:
response = methods.getPatientNotificationNumbers(1)
but when I console.log(response), it's basically {state: 'pending'}, which I guess is an unresolved promise.
So I'm all over the place and I'm open to using whatever libraries make things easy. I am not married to mockery, sinon or whatever else. Any suggestions would help.
Thanks!

Answer 1

So another approach is to use a combination of rewire and deride.
var should = require('should-promised');
var rewire = require('rewire');
var Somefile = rewire('./path/to/file');
var deride = require('deride');
var sut, mockSql;
before(function() {
mockSql = deride.stub(['query']);
Somefile.__set__('sqlServer', mockSql);
sut = new Somefile();
});
describe('getting patient notification numbers', function() {
beforeEach(function() {
mockSql.setup.query.toResolveWith(fakeSqlResponse);
});
it('resolves the promise', function() {
sut.getPatientNotificationNumbers(id).should.be.fulfilledWith(expectedPhoneNumbers);
});
it('queries Sql', function(done) {
sut.getPatientNotificationNumbers(id).then(function() {
mockSql.expect.query.called.once();
done();
});
});
});
This will mean that you do not need to change your production code and you can easily start testing the un-happy paths using something like this:
it('handles Sql errors', function(done) {
mockSql.setup.query.toRejectWith(new Error('Booom'));
sut.getPatientNotificationNumbers(id)
.then(function(){
done('should not have resolved');
})
.catch(function(e) {
e.should.be.an.Error;
e.message.should.eql('Booom');
done();
});
});
Or even more succinctly:
it('handles Sql errors', function(done) {
mockSql.setup.query.toRejectWith(new Error('Booom'));
sut.getPatientNotificationNumbers(id).should.be.rejectedWith(/Booom/);
});

Answer 2

I would zoom out a little bit and think of the test strategy. Assume that the goal is to test your model layer (methods) on top of the sql server. It can be done without stubbing out sql server. Your test suite layer can have set of util methods to create, initialize and drop the db which can be called from before, beforeEach etc.
Pros of doing this:
Testing real product code path is better (than stubbed code path).
Stubbing is better if you suspect the underlying layer bugs to generate noise. sqlserver layer is likely stable.
model layer seem to be simple enough that does not require testing in isolation.
Stubbing would make sense if you are trying to test sqlserver failure handling in your model layer. Then the stub layer can fake such errors - to exercise error paths in model code.
This is based on limited view of your problem. If there is more to it. Pl do share and we can take it from there.

Answer 3

It seems to me your intent is to test the function your passing the the .then() method, not the sqlserver library nor the actual promise it returns. We can assume those have already been tested.
If this is the case, you can simply factor out that function (the one that extracts the phone numbers from the SQL result) and test it independently.
Your code would become something along the lines of:
var getNumbers = require('./getNumbers');
function getPatientNotificationNumbers(patientId) {
patientId = patientId && patientId.toString();
var sql = "SELECT * FROM [notification_phone_number] ";
sql += "WHERE patient_id = " + escapeSql(patientId);
return sqlServer.query(sql).then(getNumbers);
}
... and your ./getNumbers.js file would look something like:
function getNumbers(results) {
var phoneNumbers = _.map(results[0], function (result) {
var obj = {
id: result.id,
phoneNumber: result.phone_number,
isPrimary: result.is_primary,
isVerified: result.is_verified,
patientId: result.patient_id
}
return obj;
});
return phoneNumbers;
}
module.exports = getNumbers;
Now you can test it independently:
var getNumbers = require('../path/to/getNumbers');
...
it('should get the patient notification numbers', function(done) {
var sampleResults = [ ... ]; // sample results from sqlServer
var phoneNumbers = getNumbers(sampleResults);
assert(...); // make what ever assertions you want
});