SwiftCheck ( https://github.com/typelift/SwiftCheck )

Date+Arbitrary.swift

// MARK: Date + SwiftCheck

extension Date: RandomType {
    public static func randomInRange<G : RandomGeneneratorType>(_ range : (Date, Date), gen : G) -> (Date, G) {
        let (min, max) = range
        let (t, gen2) = Double.randomInRange((min.timeIntervalSince1970, max.timeIntervalSince1970), gen: gen)
        return (Date(timeIntervalSince1970: t), gen2)
    }
}

extension Date: Arbitrary {
    public static var arbitrary: SwiftCheck.Gen<Date> {
        return Gen.fromElements(in: Date(timeIntervalSince1970: 0)...Date(timeIntervalSince1970: TimeInterval(Int32.max)))
    }

    /// - See Also: `SwiftCheck.Double.shrink`
    ///   - https://github.com/typelift/SwiftCheck/blob/794a986232e70bebe008e776a7e181d766aee254/Sources/SwiftCheck/Arbitrary.swift#L266-L293
    public static func shrink(_ date:
        let double = date.timeIntervalSince1970
        let tail = Int64(double).shrinkIntegral.map { Date(timeIntervalSince1970: Double($0)) }
        if double.sign == .minus {
            return [Date(timeIntervalSince1970: Swift.abs(double))] + tail
        }
        return tail
    }
}