Little bug in spy.printf "%*" formatter

[eauc]

First of all, many thanks for all your hard work on sinon ;)

• Sinon version : v2.0.0
• Environment : all ? found in node v4
• Example URL : n/a
• Other libraries you are using: sinon-chai, chai

What did you expect to happen?
In the spy.printf(format, args...) function,
when using the "%*" formatter, and passing a list of strings as arguments,
I'd expect all the string to be unquoted.

What actually happens
the first string is unquoted,
all the others ones are quoted.

How to reproduce
npm install sinon@2.0.0
$ node

const sinon = require("sinon")
const spy = sinon.spy()
spy.printf("%*", "a","b","c")
a, "b", "c"

The Bug

In lib/sinon/util/core/format.js:

var formatter = formatio.configure({
    quoteStrings: false,
    limitChildrenCount: 250
});

module.exports = function format() {
    return formatter.ascii.apply(formatter, arguments);
};

you're calling formatio.ascii with all the arguments of your sinonFormat function.

In lib/sinon/spy-formatters.js

module.exports = {
    ....
    "*": function (spyInstance, args) {
        return args.map(sinonFormat).join(", ");
    }
};

You're calling sinonFormat directly with map.

• sinonFormat is called with (value, index, collection)
• formatio.ascii is thus called with (value, index, collection)
• formatio.ascii expect (value, processedFlad, indentValue)

the index masquerade as the processedFlag, resulting in the first string being correctly unquoted (index 0 == false) and all the others being quoted (index>0 == true)

Context

I tried to make the sinon-chai module work with sinon@2.0.0.
I ran the tests for sinon-chai, and the only error is in the format of the expectation messages.
I traked it down to this little bug in sinon.

[fatso83]

Thanks for your detailed investigation. That helps a lot! Do you have any chance of fixing this with a small PR?