使NSTimeZone在单元测试中无故障 [英] Making NSTimeZone Trouble Free in Unit Tests

问题描述

以下是在Objective-C中对日历代码进行单元测试的问题：时区包含有关夏令时的信息，所以您在夏季写一个测试，预计6月10日上午6点02分发生。您的测试通过，以后，当您不是DST，您正在运行测试，并且您失败了，因为当您获得时区时，日光灯关闭。

似乎是一个简单的方法来告诉它给dst打开的时区？

我正在考虑做一个类别，以便我拦截时区调用，但这听起来很凌乱，因为我不知道你正在操作的日期。

当然，我可以写所有的测试来检查时区设置，然后只是转移了我所有的期望，但这听起来像是所有可能的最糟糕的选择。

解决方案

区域特定的时区必须考虑到日光节省时间以准确计算两个日期（和时间）之间的间隔。如果您对此不感兴趣，也许您可​​以使用UTC时区

例如，新西兰标准时间定义为UTC + 12：00，新西兰夏令时被定义为UTC + 13：00。虽然新西兰当地时间在夏令时间有所不同，但UTC + 12：00的时间保持不变（也就是说，使用UTC + 12：00的其他国家也不会因为夏令时而神奇地前进在新西兰开始）

您可以通过提供UTC偏移量作为名称来实现：

  NSTimeZone * utc_plus12 = [NSTimeZone timeZoneWithName：@UTC + 12：00]; 
  

了解您所在地区夏令时的UTC偏移量，并使用它。

So here's the problem with doing unit tests of calendar code in Objective-C: the Timezone contains the information about daylight savings, so you write a test in the summer, expecting sunrise on June 10th to occur at 6:02 am. Your test passes, later, you are running the test when it's not DST and you get a failure, because when you get the timezone, daylightsavings is turned off.

There doesn't seem to be a simple way to just tell it to give you the timezone with dst turned on?

I was thinking about doing a category so that I would intercept the timezone call but that sounds super messy as I don't know what date you are manipulating.

Of course, I could write all my tests to check the timezone setting and then just shift all my expectations but that sounds like the worst of all possible choices.

解决方案

Region-specific timezones must take into account daylight saving time in order to accurately calculate intervals between two dates (and times). If you aren't interested in this, perhaps you could use a UTC “timezone” instead, which don't change at all.

For example, New Zealand Standard Time is defined as UTC+12:00, and New Zealand Daylight Saving Time is defined as UTC+13:00. Although the local time in New Zealand differs during Daylight Saving Time, the times in UTC+12:00 remain the same (that is, every other country that also uses UTC+12:00 don't magically move forward just because Daylight Saving Time has commenced in New Zealand).

You can achieve this simply by providing that UTC offset as the name:

NSTimeZone *utc_plus12 = [NSTimeZone timeZoneWithName:@"UTC+12:00"];

Find out what UTC offset your region's daylight saving time is based on and use that.

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