Xcode: command line error error: no such module 'XCTest'

Question

I'm trying implement unit test in some of my Swift Scripts but I'm getting this error:

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/usr/lib/swift/XCTest.swiftmodule/x86_64.swiftinterface:6:19: error: no such module 'XCTest'
@_exported import XCTest
                  ^
one.swift:3:8: error: failed to load module 'XCTest'
import XCTest
       ^

This is my script:

#!/usr/bin/swift
import Foundation
import XCTest

print("my script")

Any of you knows why I'm getting this error and if there is a work around this error?

I'll really appreciate your help.