Allow providing stubs overrides for sinon.createStubInstance

[ifrost]

Purpose (TL;DR) - mandatory

Implements #1857. The solution is slightly different from what I suggested #1857 - it allows simple stub overrides or providing returned value as described in docs:

var stub = sinon.createStubInstance(MyConstructor, overrides);

overrides is an optional map overriding created stubs, for example:

var stub = sinon.createStubInstance(MyConstructor, {
    foo: sinon.stub().returnsThis()
});

is the same as:

var stub = sinon.createStubInstance(MyConstructor);
stub.foo.returnsThis();

If provided value is not a stub, it will be used as the returned value:

var stub = sinon.createStubInstance(MyConstructor, {
    foo: 3
});

is the same as:

var stub = sinon.createStubInstance(MyConstructor);
stub.foo.returns(3);

How to verify - mandatory

1. Check out this branch
2. npm install
3. npm test

[coveralls]

Pull Request Test Coverage Report for Build 2602

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.02%) to 95.261%

---

Totals
Change from base Build 2599:	0.02%
Covered Lines:	1973
Relevant Lines:	2027

---

💛 - Coveralls

[mroderick]

Thank you for your pull request.
Things have been a bit busy lately, so I am a bit behind on my open source work.
I will get around to take a closer look at this, when I can give it the attention it deserves.
Thank you for your patience

[fatso83]

[mroderick]

Thank you for your patience ❤️
This has been published as sinon@6.3.0

[fatso83]

Hmm ... isn't the pre-test checks running on the PRs? This failed after merging to master.

[mroderick]

Hmm ... isn't the pre-test checks running on the PRs? This failed after merging to master.

I think we changed the linting since the PR was created:

https://travis-ci.org/sinonjs/sinon/jobs/427844368

[mroderick]

I can fix this lint violation and update the preversion.sh to include linting

[fatso83]

The linting failed because of not using a cached reference to forEach. This makes it susceptible to bugs where people stub out Array.prototype.forEach in their own tests.

Even if we have just recently added the explicit check for this (good!), we did have a point in our pull request template just for this:

• References to standard library functions are cached.

There is a reason we have this checklists, @ifrost, so removing them should only be done if you understand why they are there in the first place and if they are irrelevant.

[mroderick]

@fatso83 #1902

[mroderick]

@fatso83 in fairness, those requirements were added after this PR was opened.

[fatso83]

@mroderick No, they were added one year ago (2017).

[mroderick]

@mroderick No, they were added one year ago (2017).

Oh!

[ifrost]

The linting failed because of not using a cached reference to forEach. This makes it susceptible to bugs where people stub out Array.prototype.forEach in their own tests.

Even if we have just recently added the explicit check for this (good!), we did have a point in our pull request template just for this:

• References to standard library functions are cached.

There is a reason we have this checklists, @ifrost, so removing them should only be done if you understand why they are there in the first place and if they are irrelevant.

Sorry, my bad! Thanks for fixing it!