public void WithArguments()
{
/* Given */
Directive original = "@a(x: 100, y: 100)";
/* When */
var modified = original
.WithArguments(
new List <Argument>(original.Arguments ?? Enumerable.Empty <Argument>())
.Concat(new[]
{
new Argument("x", new IntValue(100))
}).ToList()
);
/* Then */
Assert.Equal(2, original.Arguments?.Count);
Assert.Equal(3, modified.Arguments?.Count);
}