public void Sort_WhenCalled_CallsWithPassedArgument()
{
// Arrange
IMyInterface mock = Substitute.For <IMyInterface>();
Func <IEnumerable <int>, IOrderedEnumerable <int> > func = null;
mock.WhenForAnyArgs(x => x.Sort(Arg.Any <Func <IEnumerable <int>, IOrderedEnumerable <int> > >())).Do(
x =>
{
func = x.Arg <Func <IEnumerable <int>, IOrderedEnumerable <int> > >();
});
// Act
mock.Sort(x => x.OrderBy(y => y));
// Assert
var result = func(new[] { 6, 4 });
Assert.That(result.FirstOrDefault(), Is.Not.EqualTo(6));
Assert.That(result.FirstOrDefault(), Is.EqualTo(4));
}