Merge duplicate FluentMockVisitor classes (#698)

Author: stakx

src/Moq/FluentMockVisitor.cs

@@ -0,0 +1,194 @@
+// Copyright (c) 2007, Clarius Consulting, Manas Technology Solutions, InSTEDD.
+// All rights reserved. Licensed under the BSD 3-Clause License; see License.txt.
+
+using System;
+using System.Diagnostics;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Reflection;
+using System.Runtime.CompilerServices;
+
+using Moq.Properties;
+
+namespace Moq
+{
+	/// <summary>
+	///   This visitor translates multi-dot expressions such as `r.A.B.C` to an executable expression
+	///   `FluentMock(FluentMock(FluentMock(root, m => m.A), a => a.B), b => b.C)` that, when executed,
+	///   will cause all "inner mocks" towards the rightmost sub-expression to be automatically mocked.
+	///   The original expression can be added to the final, rightmost inner mock as a setup.
+	/// </summary>
+	internal sealed class FluentMockVisitor : ExpressionVisitor
+	{
+		internal static readonly MethodInfo FluentMockMethod =
+			typeof(FluentMockVisitor).GetMethod(nameof(FluentMock), BindingFlags.NonPublic | BindingFlags.Static);
+
+		private bool isAtRightmost;
+		private readonly Func<ParameterExpression, Expression> resolveRoot;
+		private readonly bool setupRightmost;
+
+		public FluentMockVisitor(Func<ParameterExpression, Expression> resolveRoot, bool setupRightmost)
+		{
+			Debug.Assert(resolveRoot != null);
+
+			this.isAtRightmost = true;
+			this.resolveRoot = resolveRoot;
+			this.setupRightmost = setupRightmost;
+		}
+
+		protected override Expression VisitMember(MemberExpression node)
+		{
+			Debug.Assert(node != null);
+
+			// Translate differently member accesses over transparent
+			// compiler-generated types as they are typically the
+			// anonymous types generated to build up the query expressions.
+			if (node.Expression.NodeType == ExpressionType.Parameter &&
+				node.Expression.Type.GetTypeInfo().IsDefined(typeof(CompilerGeneratedAttribute), false))
+			{
+				var memberType = node.Member is FieldInfo ?
+					((FieldInfo)node.Member).FieldType :
+					((PropertyInfo)node.Member).PropertyType;
+
+				// Generate a Mock.Get over the entire member access rather.
+				// <anonymous_type>.foo => Mock.Get(<anonymous_type>.foo)
+				return Expression.Call(null,
+					Mock.GetMethod.MakeGenericMethod(memberType), node);
+			}
+
+			// If member is not mock-able, actually, including being a sealed class, etc.?
+			if (node.Member is FieldInfo)
+				throw new NotSupportedException();
+
+			var lambdaParam = Expression.Parameter(node.Expression.Type, "mock");
+			Expression lambdaBody = Expression.MakeMemberAccess(lambdaParam, node.Member);
+			var targetMethod = GetTargetMethod(node.Expression.Type, ((PropertyInfo)node.Member).PropertyType);
+			if (isAtRightmost)
+			{
+				isAtRightmost = false;
+			}
+
+			return TranslateFluent(node.Expression.Type, ((PropertyInfo)node.Member).PropertyType, targetMethod, Visit(node.Expression), lambdaParam, lambdaBody);
+		}
+
+		protected override Expression VisitMethodCall(MethodCallExpression node)
+		{
+			Debug.Assert(node != null);
+
+			var lambdaParam = Expression.Parameter(node.Object.Type, "mock");
+			var lambdaBody = Expression.Call(lambdaParam, node.Method, node.Arguments);
+			var targetMethod = GetTargetMethod(node.Object.Type, node.Method.ReturnType);
+			if (isAtRightmost)
+			{
+				isAtRightmost = false;
+			}
+
+			return TranslateFluent(node.Object.Type, node.Method.ReturnType, targetMethod, this.Visit(node.Object), lambdaParam, lambdaBody);
+		}
+
+		protected override Expression VisitParameter(ParameterExpression node)
+		{
+			Debug.Assert(node != null);
+
+			return this.resolveRoot(node);
+		}
+
+		private MethodInfo GetTargetMethod(Type objectType, Type returnType)
+		{
+			// dte.Solution =>
+			if (this.setupRightmost && this.isAtRightmost)
+			{
+				//.Setup(mock => mock.Solution)
+				return typeof(Mock<>)
+				       .MakeGenericType(objectType)
+				       .GetMethods("Setup")
+				       .First(m => m.IsGenericMethod)
+				       .MakeGenericMethod(returnType);
+			}
+			else
+			{
+				//.FluentMock(mock => mock.Solution)
+				Guard.Mockable(returnType);
+				return FluentMockMethod.MakeGenericMethod(objectType, returnType);
+			}
+		}
+
+		// Args like: string IFoo (mock => mock.Value)
+		private Expression TranslateFluent(Type objectType,
+		                                   Type returnType,
+		                                   MethodInfo targetMethod,
+		                                   Expression instance,
+		                                   ParameterExpression lambdaParam,
+		                                   Expression lambdaBody)
+		{
+			var funcType = typeof(Func<,>).MakeGenericType(objectType, returnType);
+
+			if (targetMethod.IsStatic)
+			{
+				// This is the fluent extension method one, so pass the instance as one more arg.
+				return Expression.Call(targetMethod, instance, Expression.Lambda(funcType, lambdaBody, lambdaParam));
+			}
+			else
+			{
+				return Expression.Call(instance, targetMethod, Expression.Lambda(funcType, lambdaBody, lambdaParam));
+			}
+		}
+
+		/// <summary>
+		/// Retrieves a fluent mock from the given setup expression.
+		/// </summary>
+		private static Mock<TResult> FluentMock<T, TResult>(Mock<T> mock, Expression<Func<T, TResult>> setup)
+			where T : class
+			where TResult : class
+		{
+			Guard.NotNull(mock, nameof(mock));
+			Guard.NotNull(setup, nameof(setup));
+			Guard.Mockable(typeof(TResult));
+
+			MethodInfo info;
+			if (setup.Body.NodeType == ExpressionType.MemberAccess)
+			{
+				var memberExpr = ((MemberExpression)setup.Body);
+				memberExpr.ThrowIfNotMockeable();
+
+				info = ((PropertyInfo)memberExpr.Member).GetGetMethod();
+			}
+			else if (setup.Body.NodeType == ExpressionType.Call)
+			{
+				info = ((MethodCallExpression)setup.Body).Method;
+			}
+			else
+			{
+				throw new NotSupportedException(string.Format(Resources.UnsupportedExpression, setup.ToStringFixed()));
+			}
+
+			Guard.Mockable(info.ReturnType);
+
+			Mock fluentMock;
+			MockWithWrappedMockObject innerMock;
+			if (mock.InnerMocks.TryGetValue(info, out innerMock))
+			{
+				fluentMock = innerMock.Mock;
+			}
+			else
+			{
+				fluentMock = ((IMocked)mock.GetDefaultValue(info, useAlternateProvider: DefaultValueProvider.Mock)).Mock;
+				Mock.SetupAllProperties(fluentMock);
+
+				innerMock = new MockWithWrappedMockObject(fluentMock, fluentMock.Object);
+				//                                                    ^^^^^^^^^^^^^^^^^
+				// NOTE: Above, we are assuming that a default value was returned that is neither a `Task<T>` nor a `ValueTask<T>`,
+				// i.e. nothing we'd need to first "unwrap" to get at the actual mocked object. This assumption would seem permissible
+				// since the present method gets called only for multi-dot expressions ("recursive mocking"), which do not allow
+				// `await` expressions. Therefore we don't need to deal with `Task<T>` nor `ValueTask<T>`, and we proceed as if the
+				// returned default value were already "unwrapped".
+			}
+
+			var result = (TResult)innerMock.WrappedMockObject;
+
+			mock.Setup(setup).Returns(result);
+
+			return (Mock<TResult>)fluentMock;
+		}
+	}
+}

src/Moq/Linq/FluentMockVisitor.cs

@@ -207,7 +207,7 @@ private static Expression ConvertToSetupProperty(Expression targetObject, Expres
 				return ConvertToSetup(targetObject, left, right);
 
 			// This will get up to and including the Mock.Get(foo).Setup(mock => mock.Name) call.
-			var propertySetup = FluentMockVisitor.Accept(left);
+			var propertySetup = VisitFluent(left);
 			// We need to go back one level, to the target expression of the Setup call, 
 			// which would be the Mock.Get(foo), where we will actually invoke SetupProperty instead.
 			if (propertySetup.NodeType != ExpressionType.Call)
@@ -246,8 +246,15 @@ private static Expression ConvertToSetup(Expression targetObject, Expression lef
 			}
 
 			return Expression.NotEqual(
-				Expression.Call(FluentMockVisitor.Accept(left), returnsMethod, right),
+				Expression.Call(VisitFluent(left), returnsMethod, right),
 				Expression.Constant(null));
 		}
+
+		private static Expression VisitFluent(Expression expression)
+		{
+			return new FluentMockVisitor(resolveRoot: p => Expression.Call(null, Mock.GetMethod.MakeGenericMethod(p.Type), p),
+			                             setupRightmost: true)
+			       .Visit(expression);
+		}
 	}
 }