Unit testing a generic private static method on a base class

Tags: C#, Unit Testing

Sep 22 2011 10:35 AM

I created this useful testing method I need to create today, uses recursion to loop down through to the correct base class to execute:

   1: /// <summary>
   2: /// Execute private static method on a base of the passed sub class type
   3: /// </summary>
   4: /// <typeparam name="TSubClass">Type of sub class</typeparam>
   5: /// <param name="baseName">Base name to execute method on</param>
   6: /// <param name="methodName">Method name to execute</param>
   7: /// <param name="parameters">Parameters to use</param>
   8: /// <returns>Return from invocation</returns>
   9: public static object ExecutePrivateStaticMethodOnBase<TSubClass>(string baseName, string methodName, object[] parameters)
  10: {
  11:     // Walk up the type rope
  12:     var baseType = CheckBaseType(typeof(TSubClass), baseName, typeof(TSubClass).Name);
  13:  
  14:     var mi = baseType.GetMethods(BindingFlags.Static | BindingFlags.NonPublic)
  15:         .Where(m => m.Name == methodName).FirstOrDefault();
  16:  
  17:     if (mi == null)
  18:     {
  19:         throw new Exception(string.Format(
  20:             "Cannot find private method '{0}' on a base named '{1}' of class of type '{2}'",
  21:             methodName,
  22:             baseName,
  23:             typeof(TSubClass).Name));
  24:     }
  25:  
  26:     return mi.Invoke(null, parameters);
  27: }

The recursive method is as follows:

   1: /// <summary>
   2: /// Check base type
   3: /// </summary>
   4: /// <param name="subClassType">Sub class type to check</param>
   5: /// <param name="baseName">Base name of type</param>
   6: /// <param name="originalEntry">Original entry type</param>
   7: /// <returns>The actual type if we find it</returns>
   8: private static Type CheckBaseType(Type subClassType, string baseName, string originalEntry)
   9: {
  10:     var baseType = subClassType.BaseType;
  11:     if (baseType != null && baseType.Name == baseName)
  12:     {
  13:         return baseType;
  14:     }
  15:  
  16:     if (baseType != null)
  17:     {
  18:         return CheckBaseType(baseType, baseName, originalEntry);
  19:     }
  20:  
  21:     // Not found
  22:     throw new InvalidOperationException(string.Format("Cannot find {0} as a base type of {1}.", baseName, originalEntry));
  23: }

As you can see this just walks up the class tree to find the class that matches.

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