The internal keyword makes a class (including nested classes), property, method or field available to every consumer in the same assembly:
internal class Foo
{
internal string SomeProperty {get; set;}
}
internal class Bar
{
var myInstance = new Foo();
internal string SomeField = foo.SomeProperty;
internal class Baz
{
private string blah;
public int N { get; set; }
}
}
This can be broken to allow a testing assembly to access the code via adding code to AssemblyInfo.cs file:
using System.Runtime.CompilerServices;
[assembly:InternalsVisibleTo("MyTests")]