public void VerifyInvocationSequence()
 {
     if (!ExpectedInvocations.SequenceEqual(ActualInvocations))
     {
         Assert.Fail(
             "Expected validator invocations{0}\t{1}{0}but was{0}\t{2}{0}.",
             Environment.NewLine,
             String.Join(Environment.NewLine + "\t", ExpectedInvocations),
             String.Join(Environment.NewLine + "\t", ActualInvocations)
             );
     }
 }
 protected void ExpectInvocation(ValidatorInvocation invocation)
 {
     ExpectedInvocations.Add(invocation);
 }