Cannot create an instance of the variable type 'Item' because it does not have the new() constraint

Question

I am trying to test a method - and getting an error:

Cannot create an instance of the variable type \'Item\' because it does not have the new() constr

Answer 1

The Item in the line:

Item i = new Item(p, 10);

refers to the generic type parameter Item of the CountTestHelper method, not the class Item. Change the generic parameter name e.g.

public void CountTestHelper() where TItem : IHasRect
{
    Rectangle rectangle = new Rectangle(0, 0, 100, 100); 
    SomeClass target = new SomeClass(rectangle);            
    Point p = new Point(10,10);
    Item i = new Item(p, 10);    
    ...
}

alternatively you can fully qualify the name of the Item class you want to create:

public void CountTestHelper() where Item : IHasRect
{
    Rectangle rectangle = new Rectangle(0, 0, 100, 100); 
    SomeClass target = new SomeClass(rectangle);            
    Point p = new Point(10,10);
    SomeNamespace.Item i = new SomeNamespace.Item(p, 10);  
}