public void TestExternalInternal()
{
var a = new Group(new int[]{4, 5, 8, 10});
Assert.True(a.External(0) == 4);
Assert.True(a.External(1) == 8);
Assert.True(a.External(2) == 9);
Assert.True(a.External(3) == -1);
Assert.True(a.External(4) == -1);
Assert.True(a.Internal(0) == -1);
Assert.True(a.Internal(1) == -1);
Assert.True(a.Internal(2) == -1);
Assert.True(a.Internal(3) == -1);
Assert.True(a.Internal(4) == 0);
Assert.True(a.Internal(5) == -1);
Assert.True(a.Internal(6) == -1);
Assert.True(a.Internal(7) == -1);
Assert.True(a.Internal(8) == 1);
Assert.True(a.Internal(9) == 2);
Assert.True(a.Internal(10) == -1);
Assert.True(a.Internal(11) == -1);
}
