Only resolve properties on substitutes that can be resolved (#51)

Author: twsouthwick

AutofacContrib.NSubstitute.Tests/AutoSubstituteOptionsFixture.cs

@@ -1,5 +1,6 @@
 using Autofac;
 using Autofac.Core;
+using Autofac.Core.Registration;
 using NUnit.Framework;
 using System;
 
@@ -74,6 +75,23 @@ public void InjectPropertiesClass()
             Assert.IsNotNull(obj.Service);
         }
 
+        [Test]
+        public void InjectPropertiesNotResolvable()
+        {
+            using var mock = AutoSubstitute.Configure()
+                .InjectProperties()
+                .SubstituteFor<WithStringProperty>()
+                .Build()
+                .Container;
+
+            // Verify that strings are not resolvable, otherwise this test won't be valid.
+            Assert.Throws<ComponentNotRegisteredException>(() => mock.Resolve<string>());
+
+            var obj = mock.Resolve<WithStringProperty>();
+
+            Assert.IsNotNull(obj.Test);
+        }
+
         [Test]
         public void InjectPropertiesInterfaceRecursive()
         {
@@ -146,6 +164,11 @@ public class WithProperties
             public ITestInterface1 Service { get; set; }
         }
 
+        public class WithStringProperty
+        {
+            public virtual string Test { get; }
+        }
+
         public class Class1
         {
         }

AutofacContrib.NSubstitute/MockHandlers/AutoPropertyInjectorMockHandler.cs

@@ -37,7 +37,14 @@ public RouteAction Handle(ICall call)
                     return RouteAction.Continue();
                 }
 
-                return RouteAction.Return(_context.Resolve(call.GetReturnType()));
+                var service = _context.ResolveOptional(call.GetReturnType());
+
+                if (service is null)
+                {
+                    return RouteAction.Continue();
+                }
+
+                return RouteAction.Return(service);
             }
         }
     }