Why is my sinon stub acting like it's calling the real function?

Question

I\'m trying to follow this example: https://www.alexjamesbrown.com/blog/development/stubbing-middleware-testing-express-supertest/ but the sinon stub doesn\'t seem to be executi

Answer 1

instead executes the actual authorization

This is exactly what is happening.

Note this code in server:

app.all('/api/*', authorization.authorize);

This resolves authorize function reference in this particular state of program and express will use this particular function (original one!) for rest of program.

This:

ensureAuthenticatedSpy = sinon.stub(authorization, 'authorize');

is called later and given that sinon has no power to change references to original authorize captured previously ... is no-op.

IOW, dependency injection in basic Javascript apps is not as simple as one might want.

To workaround, you can change original route in app.js:

app.all('/api/*', (req, res, next) => authorization.authorize(req, res, next));

Now, your closure would resolve authorization.authorize every-time it's called, enabling mocking/spying function you're interested in. However this is solution is far from elegant.