testing_fatal_error_3.swift

testing_fatal_error_3.swift

import XCTest

final class AnyEquatableTests: XCTestCase {
    func test_unsafelyUnwrapped_whenWrongTypeIsPassed_itShouldThrowFatalError() {
        // Given
        let mockState: String = "StateMock"
        
        let failureHandlerExpectation = expectation(description: "Expecting failureHandler.")
        var assertionMessage: String?
        let failureHandler: (@autoclosure () -> String, StaticString, UInt) -> Never = { message, _, _ in
            assertionMessage = message()
            failureHandlerExpectation.fulfill()
            self.unreachable()
        }
        
        let sut = AnyEquatable(
            erasing: mockState,
            failureHandler: failureHandler
        )
        
        let expectedType = String(describing: sut.erasedValue)
        let typePassed = String(describing: Int.self)
        let expectedMessage = "Trying to cast \(expectedType) to \(typePassed)!"
        
        // When
        let testCase: () -> Void = {
            _ = sut.unsafelyUnwrapped() as Int
        }
        DispatchQueue.global(qos: .userInitiated).async(execute: testCase)
        
        // Then
        waitForExpectations(timeout: 2.0) { _ in
            XCTAssertEqual(assertionMessage, expectedMessage)
        }
    }
    
    // MARK: - Helpers
    
    private func unreachable() -> Never {
        repeat {
            RunLoop.current.run()
        } while true
    }
}


AnyEquatableTests.defaultTestSuite.run()