public void Test()
{
const string pre = @"<root><child /><child /></root>";
const string post = pre;
const string xpath = "//child";
var task = new Count();
Run(pre, post, xpath, task);
}
public void InvalidXPath()
{
const string pre = @"<root><child/><child/></root>";
const string xpath = "//";
var task = new Count();
Assert.Throws<TaskExecutionException>(() => Run(pre, null, xpath, task));
}