Question

I would like to know what is the best way to write custom extensions methods for Microsoft Visual Studio Unit Testing Assert class.

Answer 1

If you are referring to this Assert class, then you cannot add extension methods. Extension methods can only be applied to object instances. Since this class is static, it can never be instantiated.

You could add your own custom Assert type class like so though:

public static class MyAssert {
    public static void AreEqual(object expected, object actual) {
        // TODO: throw if not equal
    }
}