IIRC XCTest only lives inside Xcode.app, so I can only think of a few options, none of them great:

• Don't build the XCTest overlay when using the command-line tools.

• Try to find some Xcode installed on your system, but only use it for XCTest.

• Try to find some Xcode installed on your system and use its SDKs.

• Complain up front that the command line tools package isn't supported for building Swift.

I think the first option is probably best for now, if I'm correct that XCTest.framework doesn't exist inside /Library/Developer/CommandLineTools.

— I think the first option is probably best for now, if I'm correct that XCTest.framework doesn't exist inside /Library/Developer/CommandLineTools.

That is the case, yes.

Trying to see if there's a quick fix for this. Can you let me know what xcrun -show-sdk-path -sdk macosx and xcrun -show-sdk-path -sdk iphonesimulator print on the machine with CommandLineTools xcode-select-ed?

(I can set up my own test machine with command line tools installed but if you happen to be around this is faster!)

Note that some of the regression tests depend on XCTest, so a Swift built from the command line tools won't pass all the tests with this solution. I think that's correct, though; marking those tests XFAIL or UNSUPPORTED would hide the fact that some parts of the stdlib and overlays aren't being tested. (We do this in other places for things like sanitizer support, but there the things that are being tested are the things that are missing.)

sorry for the delay .. I did not have my mac with me yesterday :/

here the outputs:

$> xcrun -show-sdk-path -sdk macosx
/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk

$> xcrun -show-sdk-path -sdk iphonesimulator
xcrun: error: SDK "iphonesimulator" cannot be located
xcrun: error: SDK "iphonesimulator" cannot be located
xcrun: error: unable to lookup item 'Path' in SDK 'iphonesimulator'

I do agree that marking those tests as XFAIl or UNSUPPORTED would not be ideal.

But would it be possible to hint the user that the developer dir they have selected does not include XCTest?

At first it was not obvious to me why the module was not found, I had Xcode installed and believed my setup was fine :/.