Add support for Apple iOS playgrounds

[masters3d]

Right now XCTest is not included in iOS since it is part of the sdk but not the OS in iOS.
If we want to support xctest code in iOS we need to build an iOS version to run as a framework.
https://github.com/apple/swift-corelibs-xctest

This may be impossible to do right now, we could do is fake the XCTest framework by just running the test code on the web.

[masters3d]

This has support for playgrounds
https://github.com/kylef/Spectre

we would need to create boiler plate templates that could create xctest and spectre for playgrounds code
we could use the python gby
https://github.com/apple/swift/blob/2a25a8c14fecaaca68d881fcbcba71a85bcc1e9d/validation-test/stdlib/CollectionCasts.swift.gyb

or a stencil template using sourcery
https://github.com/krzysztofzablocki/Sourcery/blob/master/Templates/AutoMockable.stencil

The adantage of sourcery is that it alreay has some templates for linux declaration of xctest.

[dylanbeadle]

I've had some success using https://github.com/Liquidsoul/XCTestPlayground in an iOS Playground , but not all asserts are supported property, so some tests in exercises fail. I also have a build script that automates the download of all exercises and creates the playgroundbook file used in iOS playgrounds.

I'm exploring if we can use https://github.com/apple/swift-corelibs-xctest/blob/master/Sources/XCTest/Public/XCTAssert.swift for the assert functions to avoid the issues. I'll update this thread if I have success.

[masters3d]

Now you can subscribe to playgrounds from your favorite third-party creators, then browse and download their content directly within Swift Playgrounds.

https://itunes.apple.com/us/app/swift-playgrounds/id908519492?mt=8