ReturnsAndDoes.cs

using System.Collections.Generic;
using NUnit.Framework;

namespace NSubstitute.Acceptance.Specs
{
    public class ReturnsAndDoes
    {
        public interface IFoo { IBar GetBar(int i); } 
        public interface IBar { }

        private IFoo sub;

        [SetUp]
        public void SetUp()
        {
            sub = Substitute.For<IFoo>();
        }

        [Test]
        public void Set_callback_via_extension_method()
        {
            var bar = Substitute.For<IBar>();
            var wasCalled = false;
            sub.GetBar(2).Returns(bar).AndDoes(x => wasCalled = true);
            sub.GetBar(1);

            Assert.That(wasCalled, Is.False);
            var result = sub.GetBar(2);
            Assert.That(result, Is.EqualTo(bar));
            Assert.That(wasCalled, Is.True);
        }

        [Test]
        public void Add_multiple_callbacks_and_ignore_args()
        {
            var bar = Substitute.For<IBar>();
            var wasCalled = false;
            var argsUsed = new List<int>();
            sub.GetBar(2)
               .ReturnsForAnyArgs(bar)
               .AndDoes(x => wasCalled = true)
               .AndDoes(x => argsUsed.Add(x.Arg<int>()));

            var result1 = sub.GetBar(42);
            var result2 = sub.GetBar(9999);
            Assert.That(wasCalled, Is.True);
            Assert.That(argsUsed, Is.EquivalentTo(new[] {42, 9999}));
            Assert.AreSame(result1, bar);
            Assert.AreSame(result2, bar);
        }

        [Test]
        public void Interaction_with_other_callback_methods()
        {
            var calledViaWhenDo = false;
            var calledViaArgDo = false;
            var calledViaAndDoes = false;

            sub.GetBar(2).Returns(Substitute.For<IBar>()).AndDoes(x => calledViaAndDoes = true);
            sub.When(x => x.GetBar(2)).Do(x => calledViaWhenDo = true);
            sub.GetBar(Arg.Do<int>(x => calledViaArgDo = true));

            Assert.False(calledViaAndDoes && calledViaArgDo && calledViaWhenDo);

            sub.GetBar(2);

            Assert.That(calledViaAndDoes);
            Assert.That(calledViaArgDo);
            Assert.That(calledViaWhenDo);
        }
    }
}