What if you want to put some common unit test code in a framework? By default, you can not. However if you create protocols for XCTestCase and company, you can.

UnitTestSharedINFramework.swift

// Framework code
public protocol _XCTestCaseProtocol: NSObjectProtocol {
	func _expectation(description: String) -> _XCTestExpectationProtocol
}
public protocol _XCTestExpectationProtocol {
	func fulfill()
}

extension _XCTestCaseProtocol {
	public func _expectation(description: String) -> _XCTestExpectationProtocol {
		return perform(NSSelectorFromString("expectationWithDescription:")
			, with: description).takeUnretainedValue() as! _XCTestExpectationProtocol
	}
}

// --------------------------------------------------------
// Unit Test Bundle
extension XCTestCase: _XCTestCaseProtocol {}
extension XCTestExpectation: _XCTestExpectationProtocol {}