Add ability to compare tuples

[abbeycode]

I have test code like this:

let listOfTuples = //...
expect(listOfTuples).to(equal([
    (name: "Name", description: "Description")
]))

I get a compiler error:

Cannot invoke 'equal' with an argument list of type '([(name: String, description: String)])'

I tried removing the labels in the tuple, and I get the same error (but without the labels in the type the error prints). Is there a way to accomplish this type of matching with Nimble?

[wizzardchao]

It seems it's a swift compiler's bug to support array of tuple. I can also not append an element to an array of tuple.

[jeffh]

Unfortunately, swift currently doesn't have a clean way of representing arbitrary tuples for Nimble to perform equality against. There only way is to implement it for each tuple of a given size (unlabeled).

For now, you'll have to compare each element in the tuple manually.

[abbeycode]

It looks like this is coming in Swift 2.2: https://github.com/apple/swift-evolution/blob/master/proposals/0015-tuple-comparison-operators.md

[briancroom]

That feature from that proposal is now available in the latest Xcode, however it doesn't do much to help with @abbeycode's original feature request.

Specifically, the standard library now provides additional overloads of == and the comparison operators that accept tuples as their lhs and rhs arguments, however the tuples themselves aren't made Equatable or Comparable. This means that the new functionality is not automatically made available to Nimble's matchers, and it also means that comparing arrays of tuples hasn't gotten any less painful.

let tuple = (1, 2)
tuple == tuple // This works now!
expect(tuple).to(equal(tuple)) // Error: Cannot invoke 'equal' with an argument list of type '(Int, Int)'

let tuples = [(1, 2)]
tuples == tuples // Error: Binary operator '==' cannot be applied to two '[(Int, Int)]' operands

[jonnolen]

in this case: expect(tuple == tuple2).to(beTrue()) is what I ended up falling back to. still won't handle arrays but solves the expected type issue.

[ikesyo]

Let's follow the followings:

• Tuples conform to Equatable, Comparable, and Hashable swiftlang/swift-evolution#1109
• https://forums.swift.org/t/tuples-conform-to-equatable-comparable-and-hashable/34156

[wearhere]

Looks like the proposal was accepted and is now being implemented 🎉 swiftlang/swift#28833

[revolter]

It was merged but then it was reverted :(

[ikesyo]

Implemented equal overloads for tuples of up to 6 elements in #880.

For arrays of tuples, you can use elementsEqual instead:

expect([(1, "2"), (3, "4")]).to(elementsEqual([(1, "2"), (3, "4")], by: ==))