title: How to determine if the values in a DateTime are valid?
body: <p>We have a line of code:</p>
  
  <pre><code>DateTime.Now.AddMinutes(-1);
  </code></pre>
  
  <p>Which ran at 2:00 on the morning of the 29th of March 2015 in the UK. The returned value was 1:59, however because of the transition to summer time 1:59 didn't actually happen and caused exceptions further down the line.</p>
  
  <p>In my opinion this is a bug in .NET however in lieu of getting a fix to the framework how can we validate that this is a valid DateTime before the following lines throw exceptions?</p>
  
  <p>I'm really looking for an extension method along the lines of.</p>
  
  <pre><code>if(!theDate.IsValidInTimezone(TimeZoneInfo.Local))
  {
    // the time is not valid
  }
  </code></pre>