Can I get a method attribute from a generic delegate?

Question

I'm sure there's an answer already on the forum somewhere, but I haven't been able to find it so far. As per this example I am using anonymous methods in conjunction with a delegate in order to have different methods with the different parameters but the same return type all work as function parameters:

public delegate TestCaseResult Action();
...

[TestDescription("Test whether the target computer has teaming configured")]
public TestCaseResult TargetHasOneTeam()
{
  // do some logic here and return
  // TestCaseResult
}

[TestDescription("Test whether the target computer has the named team configured")]
public TestCaseResult TargetHasNamedTeam(string teamName)
{
  // do some logic here and return
  // TestCaseResult
}
...

public static void TestThat(TestCaseBase.Action action)
{
  TestCaseResult result = action.Invoke();

  // I want to get the value of the TestDescription attribute here
}
...

// usage
TestThat(() => TargetHasOneTeam());

TestThat(() => TargetHasNamedTeam("Adapter5"));

As you can see from the example, I'd really like to be able to get the TestDescriptionAttribute attribute from within the TestThat() function. I've already poked through the Action parameter which contains my method but haven't been able to "find" my TargetHasOneTeam() method.

Answer 1

If you change TestThat(() => TargetHasOneTeam()) (you wrapping your delegate into another action) to TestThat(TargetHasOneTeam) and change TestThat like this:

public static void TestThat(TestCaseBase.Action action)
{
  TestCaseResult result = action.Invoke();
  var attrs = action.GetInvocationList()[0].Method.GetCustomAttributes(true);

  // I want to get the value of the TestDescription attribute here
}

will give you what you need.

With expressions:

public static void TestThat(Expression<Func<TestResult>> action)
{
    var attrs = ((MethodCallExpression)action.Body).Method.GetCustomAttributes(true);

    var result = action.Compile()();
}