Unit Testing with ControllerActionInvoker to invoke action with parameters - asp.net-mvc

Question

I use ControllerActionInvoker to invoke controller actions form unit tests
var controllerInvoker = new ControllerActionInvoker();
var result = controllerInvoker.InvokeAction(
testController.ControllerContext, "Default" );
How do I use it to call an action that has parameters?
[AcceptVerbs( HttpVerbs.Post )]
[ActionException( SomeAttribute )]
public SomeResult AddMethod( long[] Ids )
{
//some code
}

Answer 1

From the documentation it looks like you want to use the InvokeActionMethod method which allows you to pass parameters in an IDictionary as the third argument.
The ControllerContext actually carries with it additional data that the controller will use for binding (filters, model binders, route data). Your argument will need to be passed through the ControllerContext.
I found an example about unit testing controllers.

Answer 2

You shouldn't use the ControllerActionInvoker from within your unit tests. What are you actually trying to accomplish?
If you're trying to test the behavior of your actions, just call them directly (they are just regular methods). If you're trying to test the behavior of your filters, create a mock context for the filter and call its OnXxx() method.

Answer 3

I use the ControllerActionInvoker because I want to write specification tests around my controllers rather than low level unit tests. What I have found is that my implementation of the ControllerActionInvoker has had to evolve based on what I am testing but so for the following has worked for me.
class ControllerSpecActionInvoker<TResult> : ControllerActionInvoker where
TResult : ActionResult
{
private readonly Expression body;
public ControllerSpecActionInvoker(Expression body)
{
this.body = body;
}
public TResult Result { get; private set; }
protected override void InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult)
=> Result = actionResult as TResult;
protected override IDictionary<string, object> GetParameterValues(ControllerContext controllerContext, ActionDescriptor actionDescriptor)
{
if (body is MethodCallExpression methodCall)
{
return methodCall.Method.GetParameters()
.Zip(methodCall.Arguments.Select(GetArgumentAsConstant), (param, arg) => new { param.Name, Value = ChangeType(arg.Value, param.ParameterType) })
.ToDictionary(item => item.Name, item => item.Value);
}
return base.GetParameterValues(controllerContext, actionDescriptor);
}
private ConstantExpression GetArgumentAsConstant(Expression exp)
{
switch (exp)
{
case ConstantExpression constExp:
return constExp;
case UnaryExpression uranExp:
return GetArgumentAsConstant(uranExp.Operand);
}
throw new NotSupportedException($"Cannot handle expression of type '{exp.GetType()}'");
}
private static object ChangeType(object value, Type conversion)
{
var t = conversion;
if (!t.IsGenericType || t.GetGenericTypeDefinition() != typeof(Nullable<>)) return Convert.ChangeType(value, t);
if (value == null) return null;
t = Nullable.GetUnderlyingType(t);
return Convert.ChangeType(value, t);
}
}
For my purposes this is used in specification fixture base class and auto mock dependencies but the essence of how you use it is like this:
var actionInvoker = new ControllerSpecActionInvoker<ActionResult>(Expression<Func<ActionResult|JsonResult|Etc>>);
actionInvoker.InvokeAction(<controller context>, <name of the action>);
Result = actionInvoker.Result;
So it might look something like this which is not test. Most of the cruft can be hidden away in a base class:
class MyController : Controller
{
JsonResult MyAction(int i) { return Json(new {}); }
}
class MyControllerFixture
{
[Test]
public void ReturnsData()
{
var controller = new MyController();
var controllerContext = new ControllerContext
{
RouteData = new RouteData(),
HttpContext = httpContextBase,
};
controllerContext.Controller = controller;
controller.ControllerContext = controllerContext;
Action<JsonResult> act = controller.MyAction(1);
var actionInvoker = new ControllerSpecActionInvoker<JsonResult>(act.Body);
actionInvoiker.Result.Should().NotBeNull();
}
}