Supplementary test helper code for https://jakubturek.com/bottom-up-unit-testing/

DateFromString.swift

extension String {
  var date: Date {
    let formatter = DateFormatter()
    formatter.timeZone = TimeZone(secondsFromGMT: 0)
    formatter.dateFormat = "yyyy-MM-dd HH:mm:ss"

    guard let date = formatter.date(from: self) else {
      fatalError("Cannot build a date from \(self) string")
    }

    return date
  }
}

class DateFromStringSpec: QuickSpec {
  override func spec() {
    describe("String+Date") {
      it("should return correct date for 1990-01-09 12:00:00") {
        expect("1990-01-09 12:00:00".date)
          == Date(timeIntervalSince1970: 631886400)
      }

      it("should return correct date for 2020-11-11 11:11:11") {
        expect("2020-11-11 11:11:11".date)
          == Date(timeIntervalSince1970: 1605093071)
      }
    }
  }
}