allPass and beNil can't work together

[nandin-borjigin]

• I have read CONTRIBUTING and have done my best to follow them.

What did you do?

let a: Double? = nil
let b: Double? = nil
expect([a, b]).to(allPass(beNil()))

What did you expect to happen?

The expectation should pass

What actually happened instead?

It fails instead

Environment

• Quick: Irrelevant
• Nimble: 1.0 Nimble-iOS
• Xcode Version: Version 8.2.1 (8C1002)
• Swift Version: Xcode Default
• Package manager : None, only using git submodule

Project that demonstrates the issue

Three line of code shown above will reproduce the issue

[sigito]

According to AllPassTest WAI

[nandin-borjigin]

Okay, then why? Expecting [nil, nil, nil] to allPass a beNil() matcher is intuitive, isn't it?

[jeffh]

This is a bug. It was a limitation of an older implementation of Nimble that I think isn't a problem anymore.

[jeffh]

Hm, it's still a problem with the type hierarchy ATM. Perhaps a future release a Nimble will properly handle this situation.

[ikesyo]

This is still happening in 2018. Looks like the problem here is that the type evaluated in beNil() is Double?? and the value is Optional.some(.none) so that value does not satisfy beNil() matcher.

• beNil<T>() -> Predicate<T> is evaluated as beNil<Double?>() -> Predicate<Double?>
• So let actualValue = try actualExpression.evaluate() is Double??
• actualValue == nil will be false because the actualValue is Optional<Double?>.some(.none) which is not nil in that context