title: How do I stub/mock out a call to the base class inside my method
body: <p>I have a method I need to test and inside the method there is a call to the same base class method. To write a unit test do I need to mock/stub out this 'base.ResolveDate(comparisonSeries, targetDate)' method? How would I do it? I don't think extracting out an interface here would work!</p>
  
  <pre><code>public override DateTime ResolveDate(ISeries comparisonSeries, DateTime targetDate)
  {
      if (comparisonSeries == null)
      {
          throw new ArgumentNullException("comparisonSeries");
      }
  
      switch (comparisonSeries.Key)
      {
          case SeriesKey.R1:
          case SeriesKey.R2:
          case SeriesKey.R3:
          case SeriesKey.R4:
          case SeriesKey.R5:
              return DateHelper.PreviousOrCurrentQuarterEnd(targetDate);
      }
  
      return base.ResolveDate(comparisonSeries, targetDate);
  }
  </code></pre>