using System;
class MyClass {
    public string InstanceMethod(string s) {
    return ("Instance String " + s);
    }
}
class MyClass2 {
    public string InstanceMethod2(string s) {
    return ("Instance String2 " + s);
    }
}
public delegate string DelegatedMethod(string s);

class TestClass {
    public static void WriteDelegate (string label, Delegate d) {
    Console.WriteLine("Invocation list targets for {0}:",label);
    foreach(Delegate x in d.GetInvocationList())
        Console.WriteLine("{0}",x.Target);
    }

    public static void Main() {
    MyClass myInstance = new MyClass();
    DelegatedMethod delInstance = new DelegatedMethod(myInstance.InstanceMethod);
    MyClass2 myInstance2 = new MyClass2();
    DelegatedMethod delInstance2 = new DelegatedMethod(myInstance2.InstanceMethod2);
    DelegatedMethod [] sourceArray = {delInstance, delInstance2, delInstance2, delInstance};
    DelegatedMethod [] remove1 = {delInstance};
    DelegatedMethod [] remove2 = {delInstance2, delInstance2};
    DelegatedMethod [] remove3 = {delInstance2, delInstance};
    DelegatedMethod [] remove4 = {delInstance, delInstance2};
    DelegatedMethod [] remove5 = {delInstance, delInstance};
    Delegate source = Delegate.Combine(sourceArray);
    // Display invocation list of source
    TestClass.WriteDelegate("source", source);
    //Test 1: value occurs in source twice.
    Delegate value1 = Delegate.Combine(remove1);
    Delegate result1 = Delegate.Remove(source, value1);
    TestClass.WriteDelegate("value1", value1);
    if (result1==null) {
        Console.WriteLine("removal test 1 result is null");
    } else {
        TestClass.WriteDelegate("result1", result1);
    }
    //Test 2: value matches the middle two elements of source.
    Delegate value2 = Delegate.Combine(remove2);
    Delegate result2 = Delegate.Remove(source, value2);
    TestClass.WriteDelegate("value2", value2);
    if (result2==null) {
        Console.WriteLine("removal test 2 result2 is null");
    } else {
        TestClass.WriteDelegate("result2", result2);
    }
    //Test 3: value matches the last two elements of source.
    Delegate value3 = Delegate.Combine(remove3);
    Delegate result3 = Delegate.Remove(source, value3);
    TestClass.WriteDelegate("value3", value3);
    if (result3==null) {
        Console.WriteLine("removal test 3 result3 is null");
    } else {
        TestClass.WriteDelegate("result3", result3);
    }
    //Test 4: value matches the first two elements of source.
    Delegate value4 = Delegate.Combine(remove4);
    Delegate result4 = Delegate.Remove(source, value4);
    TestClass.WriteDelegate("value4", value4);
    if (result4==null) {
        Console.WriteLine("removal test 4 result4 is null");
    } else {
        TestClass.WriteDelegate("result4", result4);
    }
    //Test 5: value does not occur in source.
    Delegate value5 = Delegate.Combine(remove5);
    Delegate result5 = Delegate.Remove(source, value5);
    TestClass.WriteDelegate("value5", value5);
    if (result5==null) {
        Console.WriteLine("removal test 5 result5 is null");
    } else {
        TestClass.WriteDelegate("result5", result5);
    }
    //Test 6: value exactly matches source.
    Delegate result6 = Delegate.Remove(source, source);
    TestClass.WriteDelegate("value=source", source);
    if (result6==null) {
        Console.WriteLine("removal test 6 result6 is null");
    } else {

        TestClass.WriteDelegate("result6", result6);
    }
}
}