CreateSelfMock should cache dependencies it creates

Moq.AutoMock.Tests/DescribeCreatingSelfMocks.cs

@@ -1,27 +1,44 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
-using Moq.AutoMock.Tests.Util;
-
-namespace Moq.AutoMock.Tests
-{
-    [TestClass]
-    public class DescribeCreatingSelfMocks
-    {
-        [TestMethod]
-        public void Self_mocks_are_useful_for_testing_most_of_class()
-        {
-            var mocker = new AutoMocker();
-            var selfMock = mocker.CreateSelfMock<InsecureAboutSelf>();
-            selfMock.TellJoke();
-            Assert.IsFalse(selfMock.SelfDepricated);
-        }
-
-        [TestMethod]
-        public void It_can_self_mock_objects_with_constructor_arguments()
-        {
-            var mocker = new AutoMocker();
-            var selfMock = mocker.CreateSelfMock<WithService>();
-            Assert.IsNotNull(selfMock.Service);
-            Assert.IsNotNull(Mock.Get(selfMock.Service));
-        }
-    }
-}
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Moq.AutoMock.Tests.Util;
+
+namespace Moq.AutoMock.Tests
+{
+    [TestClass]
+    public class DescribeCreatingSelfMocks
+    {
+        [TestMethod]
+        public void Self_mocks_are_useful_for_testing_most_of_class()
+        {
+            var mocker = new AutoMocker();
+            var selfMock = mocker.CreateSelfMock<InsecureAboutSelf>();
+            selfMock.TellJoke();
+            Assert.IsFalse(selfMock.SelfDepricated);
+        }
+
+        [TestMethod]
+        public void It_can_self_mock_objects_with_constructor_arguments()
+        {
+            var mocker = new AutoMocker();
+            var selfMock = mocker.CreateSelfMock<WithService>();
+            Assert.IsNotNull(selfMock.Service);
+            Assert.IsNotNull(Mock.Get(selfMock.Service));
+        }
+
+        [TestMethod]
+        [Description("Issue 130")]
+        public void It_reuses_dependencies_when_creating_self_mock()
+        {
+            var mocker = new AutoMocker();
+            var service = mocker.CreateSelfMock<AbstractService>();
+            Assert.IsTrue(ReferenceEquals(service.Dependency, mocker.GetMock<IDependency>().Object));
+        }
+
+        public abstract class AbstractService
+        {
+            public IDependency Dependency { get; }
+            public AbstractService(IDependency dependency) => Dependency = dependency;
+        }
+
+        public interface IDependency { }
+    }
+}

Moq.AutoMock/AutoMocker.cs

@@ -246,12 +246,14 @@ public T CreateSelfMock<T>() where T : class?
         public T CreateSelfMock<T>(bool enablePrivate) where T : class?
         {
             var context = new ObjectGraphContext(enablePrivate);
-            if (!TryGetConstructorInvocation(typeof(T), context, out _, out IInstance[]? arguments))
+            if (!TryGetConstructorInvocation(typeof(T), context, out ConstructorInfo? ctor, out IInstance[]? arguments))
             {
                 throw new ArgumentException(
                     $"Did not find a best constructor for `{typeof(T)}`. If your type has a non-public constructor, set the 'enablePrivate' parameter to true for this {nameof(AutoMocker)} method.");
             }
 
+            CacheInstances(arguments.Zip(ctor.GetParameters(), (i, p) => (p.ParameterType, i)));
+
             var mock = new Mock<T>(MockBehavior, arguments.Select(x => x.Value).ToArray())
             {
                 DefaultValue = DefaultValue,