Add new behavior for setup scope runs

When the pipeline is run in a `SetupScope`, we should not run the entire pipeline, but rather just the behaviors we know are safe for execution during setup, specifically `MockContextBehavior` (to set up the `MockContext.CurrentInvocation` and `MockContext.CurrentSetup`) and `DefaultValueBehavior` to return a default value for further fluent API invocations to work on.

This simplifies the behaviors since they don't need to check and bail during active setup scopes, and makes them more self-contained.

src/Moq/Moq.Sdk/SetupScopeBehavior.cs

@@ -0,0 +1,29 @@
+using System.Linq;
+using Stunts;
+
+namespace Moq.Sdk
+{
+    /// <summary>
+    /// A behavior that skips all behaviors that do not apply during a setup scope.
+    /// </summary>
+    public class SetupScopeBehavior : IStuntBehavior
+    {
+        /// <summary>
+        /// Applies only if <see cref="SetupScope.IsActive"/> is <see langword="true"/>.
+        /// </summary>
+        public bool AppliesTo(IMethodInvocation invocation) => SetupScope.IsActive;
+
+        /// <summary>
+        /// Skips all non-setup behaviors from execution.
+        /// </summary>
+        public IMethodReturn Execute(IMethodInvocation invocation, GetNextBehavior next)
+        {
+            foreach (var behavior in invocation.Target.AsMock().Behaviors.Where(x => !(x is DefaultValueBehavior) && !(x is MockContextBehavior)))
+            {
+                invocation.SkipBehaviors.Add(behavior.GetType());
+            }
+
+            return next().Invoke(invocation, next);
+        }
+    }
+}

src/Moq/Moq.Sdk/StrictMockBehavior.cs

@@ -10,8 +10,6 @@ namespace Moq.Sdk
     /// </summary>
     public class StrictMockBehavior : IStuntBehavior
     {
-        IStuntBehavior fallback = new DefaultValueBehavior();
-
         /// <summary>
         /// Always returns <see langword="true" />
         /// </summary>
@@ -20,16 +18,6 @@ public class StrictMockBehavior : IStuntBehavior
         /// <summary>
         /// Throws <see cref="StrictMockException"/>.
         /// </summary>
-        public IMethodReturn Execute(IMethodInvocation invocation, GetNextBehavior next)
-        {
-            if (invocation == null) throw new ArgumentNullException(nameof(invocation));
-
-            if (!SetupScope.IsActive)
-                throw new StrictMockException();
-
-            // Otherwise, fallback to returning default values so that 
-            // the fluent setup API can do its work.
-            return fallback.Execute(invocation, next);
-        }
+        public IMethodReturn Execute(IMethodInvocation invocation, GetNextBehavior next) => throw new StrictMockException();
     }
-}
+}

src/Moq/Moq.Tests/MoqTests.cs

@@ -5,7 +5,6 @@
 using static Moq.Syntax;
 using Stunts;
 using Sample;
-using System.Linq;
 using Xunit.Abstractions;
 
 namespace Moq.Tests
@@ -16,6 +15,16 @@ public class MoqTests
 
         public MoqTests(ITestOutputHelper output) => this.output = output;
 
+        [Fact]
+        public void SetupDoesNotRecordCalls()
+        {
+            var calculator = Mock.Of<ICalculator>();
+
+            calculator.Setup(() => calculator.TurnOn());
+
+            Assert.Empty(calculator.AsMock().Invocations);
+        }
+
         [Fact]
         public void CanRaiseEvents()
         {

src/Moq/Moq/MockInitializer.cs

@@ -26,6 +26,7 @@ public static void Initialize(this IMocked mocked, MockBehavior behavior)
         {
             mocked.Mock.Behaviors.Clear();
 
+            mocked.Mock.Behaviors.Add(new SetupScopeBehavior());
             mocked.Mock.Behaviors.Add(new MockContextBehavior());
             mocked.Mock.Behaviors.Add(new MockRecordingBehavior());
             mocked.Mock.Behaviors.Add(new EventBehavior());