testing-api-with-calls-enum

import XCTest

protocol ApiForMocking {
    func testFunc1()
    func testFunc2()
    func testFunc3()
}

class ApiMock: ApiForMocking {

    enum Methods: String {
        case testFunc1
        case testFunc2
        case testFunc3
    }
    var calls: [Methods] = []

    func testFunc1() {
        calls.append(.testFunc1)
    }

    func testFunc2() {
        calls.append(.testFunc2)
    }

    func testFunc3() {
        calls.append(.testFunc3)
    }

}

class ServiceUnderTest {

    let api: ApiForMocking

    init(api: ApiForMocking) {
        self.api = api
    }

    func someMethod() {
        api.testFunc1()
        api.testFunc3()
    }
}

class ExampleTests: XCTestCase {

    func testSomeMethod() {
        // Given
        let mockApi = ApiMock()
        let service = ServiceUnderTest(api: mockApi)

        // When
        service.someMethod()

        // Then
        XCTAssert(mockApi.calls == [.testFunc1, .testFunc3])
        
        // The above check automatically verifies following:
        // - Both testFunc1 and testFunc3 are called and called once
        // - Order of calls
        // - No other calls were done
    }
}