Question

I want to search through all classes in a namespace for those containing a certain method. If a class contains a method then I want to create an instance of the class and run the method.

Obviously I have to start with reflection but I’m stuck on where to go.

Edit:

Interfaces are not the way I want to do this.

What I’m looking for is embedding testing functions into the code but a single calling interface. If there’s a self-test function, call it. If there isn’t, ignore it.

Answer 1

Create an interface that declares the method and then have various classes implement that interface.

You can then use reflection to find all types within an assembly that implement that interface.

From there you’ll need to create an instance of each type and then call the method. The implementation details will vary depending on what you are trying to do.

Update based on comments:

I still think an interface (or attribute) is the way to go. This is how it would work with an interface.

interface ISelfTester
{
    void SelfTest();
}

class SomeClass : ISelfTester
{
    /* ... */

    public void SelfTest() 
    {
        // test code
    }

    /* ... */
}

You could then invoke each type’s SelfTest method like so (borrowing from Dathan and Darren Kopp):

var type = typeof(ISelfTester);
var types = AppDomain.CurrentDomain.GetAssemblies()
    .Select(x => x.GetTypes())
    .SelectMany(x => x)
    .Where(x => x.Namespace == "My.Name.Space" && type.IsAssignableFrom(x));

foreach (Type t in types)
{
    ISelfTester obj = Activator.CreateInstance(t) as ISelfTester;
    obj.SelfTest();
}