How to call protected constructor in c#?

Question

How to call protected constructor?

public class Foo{
  public Foo(a lot of arguments){}
  protected Foo(){}
}
var foo=???

This obviously fails test:

public class FooMock:Foo{}
var foo=new FooMock();
Assert(typeof(Foo), foo.GetType());

Answer 1

Call parameterless protected/private constructor:

Foo foo = (Foo)Activator.CreateInstance(typeof(Foo), true);

Call non-public constructor with parameters:

  var foo = (Foo)typeof(Foo)
    .GetConstructor(
      BindingFlags.NonPublic | BindingFlags.CreateInstance | BindingFlags.Instance, 
      null, 
      new[] { typeof(double) }, 
      null
    )
    .Invoke(new object[] { 1.0 });

  class Foo
  {
     private Foo(double x){...}
  }