This NSDate extension provides a builder method intended to be used to simplify creating dates in unit tests.

NSDate+EasyTuning.swift

import Foundation

/// This `NSDate` extension provides a builder method intended to be used to 
/// simplify creating dates in unit tests.
extension NSDate {

  static func date(
    year year: Int = 1970,
    month: Int = 01,
    day: Int = 01,
    hour: Int = 00,
    minute: Int = 00,
    second: Int = 00,
    millisecond: Int = 000
    ) -> NSDate {
      let components = NSDateComponents()
      components.calendar = NSCalendar(identifier: NSCalendarIdentifierGregorian)
      components.timeZone = NSTimeZone(forSecondsFromGMT: 0)
      components.year = year
      components.month = month
      components.day = day
      components.hour = hour
      components.minute = minute
      components.second = second
      components.nanosecond = millisecond * 1000000

      guard let date = components.date else {
        preconditionFailure("Could not init NSDate from NSDateComponents")
      }

      return date
  }
}