title: Passing single value to params argument in NUnit TestCase
body: <p>I have the following test:</p>
  
  <pre><code>[ExpectedException(typeof(ParametersParseException))]
  [TestCase("param1")]
  [TestCase("param1", "param2")]
  [TestCase("param1", "param2", "param3", "optParam4", "optParam5", "some extra parameter")]
  public void Parse_InvalidParametersNumber_ThrowsException(params string[] args)
  {
      new ParametersParser(args).Parse();
  }
  </code></pre>
  
  <p>The first TestCase (obviously) fails with the following error:</p>
  
  <pre><code>System.ArgumentException : Object of type 'System.String' 
  cannot be converted to type 'System.String[]'.
  </code></pre>
  
  <p>I tried to replace the TestCase definition with this one:</p>
  
  <pre><code>[TestCase(new[] { param1 })]
  </code></pre>
  
  <p>but now I get the following compilation error:</p>
  
  <blockquote>
    <p>error CS0182: An attribute argument must be a constant expression, typeof expression or array creation expression of an attribute parameter type</p>
  </blockquote>
  
  <p>My solution for now is moving the 'one parameter' case to a different test method.</p>
  
  <p>Still, is there a way to get this test to run the same way as the others?</p>