How do I unit test private controller methods in ASP.NET MVC?

Question

What is the best practice to unit-test private methods inside a controller in ASP.NET MVC? The Currently, if I want to unit-test a private method inside a controller I have to set it to public but when I do, that method is exposed to the web.

Is the best way to move the method to a helper class?

Answer 1

You should be moving the method into a helper class that you extracted an interface to. That way it's easier to perform dependency injection and switch the underlaying implementation or mock it if needed.
Testing private methods is a code smell (or a test smell).
Use InternalsVisibleTo trick only when you must (ie you are using an untestable class and must raise an event that is hidden from you by a protected function call).

Answer 2

You should use the private object, like this:

var privateObject = new PrivateObject(this.controller);
var result = (ActionResult)privateObject.Invoke("RegisterToEvent", shippingAddressID, creditCardID);  

Answer 3

you could set the method to internal instead of private, and then set the InternalsVisibleTo attribute to the name of your test assembly.

In assembly info:

[assembly: InternalsVisibleTo("MyTestAssembly")]

Answer 4

我已经使用了PrivateObject （）方法，但我喜欢NonActionAttribute的Charlino的建议（见注释上面原来的问题），太。

Answer 5

You could create an action filter for test methods like this....

public class TestActionFilter : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
         filterContext.HttpContext.Response.Redirect("loginurl");
         //or throw exception or some other action
    }
}

Or you could make the method only publicly accessible to another assembly.

[assembly: InternalsVisibleTo("TestAssembly")]

Answer 6

You can work around that problem by limiting tests to visible methods. Any private method will be used at least by one visible method (otherwise: it can safely be deleted).

So I suggest to develop tests that call the visible methods with practical values so that the private algorithms are tested. If code is not reachable through visible methods - delete it.