Swift 3 Unit Testing - Linker fails when using import #testable - swift

Question

I'm currently trying to write unit tests (NOT UI Tests) for my (macOS) Xcode project. I have created a new Unit Test target which creates a blank unit test file for me.
This complies and links fine, but there are no tests.
As soon as I add the line #testable import Pilot, where Pilot is the name of my App Target, and I try to compile and run, it fails with this message:
Linker command failed with exit code 1 (use -v to see invocation)
I've tried everything I can find, but nothing seems to be working. The other posts I have read on here deal with this problem in UI Tests, but that is because you cannot use #testable in UI Tests. You are supposed to be able to use it in Unit Tests, but I can't figure out why this is not working.
Does anyone have any insight?
If it helps, my project is located at: https://github.com/RohanNagar/pilot-osx
Here is the full PilotTests.swift file:
import XCTest
#testable import Pilot
class PilotTests: XCTestCase {
override func setUp() {
super.setUp()
// Put setup code here. This method is called before the invocation of each test method in the class.
}
override func tearDown() {
// Put teardown code here. This method is called after the invocation of each test method in the class.
super.tearDown()
}
func testExample() {
// This is an example of a functional test case.
// Use XCTAssert and related functions to verify your tests produce the correct results.
}
func testPerformanceExample() {
// This is an example of a performance test case.
self.measure {
// Put the code you want to measure the time of here.
}
}
}

Answer 1

If your CocoaPods frameworks not included in the Test targets. It will throw this error.
I made sure running a pod install, but still it failed.
So 'pod deintegrate Yourproject.xcodeproj' and reinstall (pod install), clears the issue.

Answer 2

The import fails because the project fails to link together. I downloaded it and I get the following error trying to run it:
Showing Recent Issues
ld: framework not found Realm for architecture x86_64
Try to clean your build folder, or download the project to a new folder, and fix this issue... after that you'll be able to compile and #testable import Pilot.

Answer 3

Set Host Application to your Project Target.
Also, check the Allow testing Host Application APIs is turned on.

Answer 4

Select your test target
Select Build Phases
In the Framework Search Paths, add this
"${PODS_CONFIGURATION_BUILD_DIR}/" with recursive option