expect(fn).to.throwError() steals context

[stephenprater]

https://gist.github.com/stephenprater/10659056

I would expect this to work - but j.toJSON is executed in the context of expect, and not in j - the work around is

expect( -> j.toJSON() ).to.throwError()

That's pretty unintuitive and not really hinted at by the docs. Although it's probably not possible to know what binding to execute the function in - maybe the docs should indicate you should pass a closure to prevent this.

[shime]

👍

[janmarek]

This is javascript. You can NEVER pass object.method somewhere and expect it will be called with object as "this" argument.

[shime]

@janmarek check this out

[janmarek]

@shime How is it relevant?

Imagine the expect function receiving a parameter. How would you know inside the function if user passed function () { ... } or object.method or object.getSomething().getSomethingElse().method? Without this information you don't know what object can be set as "this" argument of call or apply.

[stephenprater]

I'm not arguing with the implementation - I get why it's like that - it's that the documentation doesn't really provide an example of this assertion being used the way you're likely to want to use it - and the behavior of javascript in this instance isn't super-obvious. I'm pretty sure I made this error report in frustration after beating my head against it for a while, and thought some body else might benefit from my suffering.