testing_fatal_errors_2.swift

testing_fatal_errors_2.swift

import Foundation

public struct AnyEquatable: Equatable {
    // MARK: - Properties
    
    public let erasedValue: Any
    private let isEqual: (AnyEquatable) -> Bool
    private let failureHandler: (_ message: @autoclosure () -> String, StaticString, UInt) -> Never

    // MARK: - Initialization
    
    public init<S>(
        id: String = UUID().uuidString,
        erasing value: S
    ) where S: Equatable {
        self.init(
            erasing: value,
            failureHandler: Swift.fatalError(_:file:line:)
        )
    }
    
    init<S>(
        erasing value: S,
        failureHandler: @escaping (_ message: @autoclosure () -> String, StaticString, UInt) -> Never
    ) where S: Equatable {
        erasedValue = value
        isEqual = { otherAnyEquatable in
            guard let other = otherAnyEquatable.erasedValue as? S else { return false }
            return other == value
        }
        self.failureHandler = failureHandler
    }
    
    // MARK: - Public API

    public func unwrapped<S>() -> S? {
        erasedValue as? S
    }
    
    public func unsafelyUnwrapped<S>() -> S {
        guard let unwrapped: S = unwrapped() else {
            let expectedType = String(describing: erasedValue)
            let typePassed = String(describing: S.self)
            failureHandler("Trying to cast \(expectedType) to \(typePassed)!", #file, #line)
        }
        return unwrapped
    }
    
    public static func == (lhs: AnyEquatable, rhs: AnyEquatable) -> Bool {
        lhs.isEqual(rhs)
    }
}