sinon.assert.calledOnceWithExactly() does not accept a single spy call

[pastelmind]

Describe the bug
According to the v9.0.2 documentation, sinon.assert.calledOnceWithExactly() can accept a single, dedicated spy call, instead of a spy. However, it throws an error instead:

const sinon = require("sinon");

let add = sinon.fake((a, b) => a + b);
add(5, 100);

// Passes
sinon.assert.calledOnceWithExactly(add, 5, 100);
// Passes
sinon.assert.calledWithExactly(add.getCall(0), 5, 100);
// Should pass, but throws in v9.0.2
sinon.assert.calledOnceWithExactly(add.getCall(0), 5, 100);

The exception message:

C:\Users\<username>\Documents\GitHub\test-proj\node_modules\sinon\lib\sinon\assert.js:110
        throw error;
        ^

Error [AssertError]: expected fake(5, 100) => 105 at Object.<anonymous> (C:\Users\<username>\Documents\GitHub\test-proj\index.js:4:1) to be called once and with exact arguments
    at Object.fail (C:\Users\<username>\Documents\GitHub\test-proj\node_modules\sinon\lib\sinon\assert.js:107:21)
    at failAssertion (C:\Users\<username>\Documents\GitHub\test-proj\node_modules\sinon\lib\sinon\assert.js:66:16)
    at Object.assert.<computed> [as calledOnceWithExactly] (C:\Users\<username>\Documents\GitHub\test-proj\node_modules\sinon\lib\sinon\assert.js:92:13)
    at Object.<anonymous> (C:\Users\<username>\Documents\GitHub\test-proj\index.js:7:14)
    at Module._compile (internal/modules/cjs/loader.js:1138:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1158:10)
    at Module.load (internal/modules/cjs/loader.js:986:32)
    at Function.Module._load (internal/modules/cjs/loader.js:879:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
    at internal/main/run_main_module.js:17:47

To Reproduce
Steps to reproduce the behavior:

1. Create a fake method with sinon.fake()
2. Call the fake method a number of times
3. Call sinon.assert.calledOnceWithExactly(), passing a dedicated spy call using getCall(), and specify the correct arguments.
4. Assertion error is raised

Expected behavior
sinon.assert.calledOnceWithExactly() should pass it normally.

Context (please complete the following information):

• Library version: v9.0.2
• Environment: Node.js 12.18.2 / Windows 10 (x86-64)
• Example URL: (none)
• Other libraries you are using: Mocha

[mroderick]

I have verified the existence locally. Don't yet know if it is a recent addition, or if it was always failing.

I'll try to find some time for a git bisect session soon, unless someone beats me to it

[mroderick]

I've managed to construct a smaller test case to produce the error

const sinon = require("sinon");

let spy = sinon.spy();
spy(5, 100);

// passes
spy.calledOnceWithExactly(spy.getCall(0), 5, 100)

// throws
sinon.assert.calledOnceWithExactly(spy.getCall(0), 5, 100);

This teaches me two things:

1. the problem originates in spy, fakeis using spy, which is why the error also manifests there
2. there's an error in the area where the assertions are constructed, namely

   sinon/lib/sinon/assert.js

   Lines 69 to 97 in f34a13e

   	function mirrorPropAsAssertion(name, method, message) {
   	var msg = message;
   	var meth = method;
   	if (arguments.length === 2) {
   	msg = method;
   	meth = name;
   	}
   	assert[name] = function(fake) {
   	verifyIsStub(fake);
   	var args = arraySlice(arguments, 1);
   	var failed = false;
   	verifyIsValidAssertion(name, args);
   	if (typeof meth === "function") {
   	failed = !meth(fake);
   	} else {
   	failed = typeof fake[meth] === "function" ? !fake[meth].apply(fake, args) : !fake[meth];
   	}
   	if (failed) {
   	failAssertion(this, (fake.printf || fake.proxy.printf).apply(fake, concat([msg], args)));
   	} else {
   	assert.pass(name);
   	}
   	};
   	}

For the second, on line 88 failed is set to false because !fake[meth] evaluates to false, because fake[meth] is undefined. That means that the matcher doesn't have a calledOnceWithExactly property on it, which kind of makes sense.

I guess the next step to investigate, is how calledWithExactly is different from calledOnceWithExactly, since that passes just fine.

But, it's past midnight here, so that'll have to wait.

[mantoni]

// passes
spy.calledOnceWithExactly(spy.getCall(0), 5, 100)

There are two things wrong with this:

1. The function never throws, it returns true or false, so it always "passes".
2. The function is called on the spy and is not supposed to receive a spy or a call as the first argument, unlike sinon.assert.* calls.

My observation is that

• spy.getCall(0).calledWithExactly(5, 100) returns true
• spy.getCall(0).calledOnceWithExactly(5, 100) is not a function, as you figured out from debugging as well :)

---

the problem originates in spy, fake is using spy

This isn't the case anymore. In our last hackathon I've separated the implementations and the common interface is now proxy.

[mantoni]

Anyway, I think this is a copy-paste bug in the documentation. It makes not much sense to check that a single call was called once. If the call wasn't made at all, the result of sinon.getCall(0) is null. It's basically a variation of sinon.assert.calledOnce wich does not claim to support a call argument in the documentation.

I'd suggest to fix it in the documentation and throw a meaningful exception if sinon.assert.calledOnce[WithExactly] receives a call as the first argument.

[dpmott]

Interesting.

I was going to write a big post about how I disagreed that it doesn't make much sense, but then I discovered that called() and calledOnce() do not accept a SpyCall type, and will not compile when given such in typescript per the type definitions in
@types/sinon.

The type of the first argument for calledOnceWithExactly() (for both the sinon and sandbox interfaces) should probably be updated to accept only SinonSpy<TArgs> instead of SinonSpy<TArgs> | SinonSpyCall<TArgs>.

I'll see if I can put together a PR to address this issue.

[dpmott]

I've looked into this, and I can't get my head wrapped around what in the sinon code base would convey typing hints to the good folk maintaining @types/sinon. I can update the documentation, but I'm unclear what other changes could/should be made in the sinon code base. What am I missing?

Also, should I just open a related issue in the @types/sinon project to request a typing change there?

[fatso83]

@dpmott While we are pondering of adding TypeScript definitions generated through JSDoc annotations ourselves, like we have done in @sinonjs/fake-timers, we are not there yet, so I would open an issue in the DefinitelyTyped project.