What's best way to mock objects in swift within XCTest?

Question

What's best way to mock objects in swift within XCTest? Is it just define classes inside functions with required functionality? Or any better options exist?

Answer 1

I recommend using Cuckoo, which is similar to Mockito.

Example Classes:

class ExampleObject {

    var number: Int = 0

    func evaluate(number: Int) -> Bool {
        return self.number == number
    }

}

class ExampleChecker {

    func check(object: ExampleObject) -> Bool {
        return object.evaluate(5)
    }

}

Example Test:

@testable import App
import Cuckoo
import XCTest

class ExampleCheckerTests: XCTestCase {

    func testCheck() {
        // 1. Arrange
        let object = MockExampleObject().spy(on: ExampleObject())
        stub(object) { object in
            when(object.evaluate(any())).thenDoNothing()
        }
        let checker = ExampleChecker()

        // 2. Action
        checker.check(object)

        // 3. Assert
        _ = verify(object).number.get
        verify(object).evaluate(any())
        verifyNoMoreInteractions(object)
    }

}

Note that the MockExampleObject class is auto-generated using custom Run script (in Build Phases), which Cuckoo docs mentions (in their install section).