Merge pull request #147 from JakeGinnivan/ExpressionFix

Expression fix

Author: JakeGinnivan

TestStack.BDDfy.Tests/Scanner/FluentScanner/ExpressionExtensionsTests.cs

@@ -209,6 +209,16 @@ public void ComplexArgument()
             AssertReturnedArguments(arguments, 1, "Foo");
         }
 
+        [Test]
+        public void ComplexArgumentMethodCall()
+        {
+            container.Target = 1;
+            container.SubContainer = new ContainerType { Target2 = "Foo" };
+
+            var arguments = GetArguments(x => x.MethodWithInputs(container.Target, container.SubContainer.ToString()), new ClassUnderTest());
+            AssertReturnedArguments(arguments, 1, "Foo");
+        }
+
         [Test]
         public void ComplexArgument2()
         {

TestStack.BDDfy/Scanners/StepScanners/Fluent/ExpressionExtensions.cs

@@ -70,8 +70,11 @@ private static IEnumerable<StepArgument> ExtractArguments<T>(Expression expressi
 
         private static IEnumerable<StepArgument> Invoke(MethodCallExpression methodCallExpression, IEnumerable<StepArgument> args)
         {
-            var value = ((ConstantExpression)methodCallExpression.Object).Value;
-            return new[] { new StepArgument(() => methodCallExpression.Method.Invoke(value, args.Select(s => s.Value).ToArray())) };
+            var constantExpression = methodCallExpression.Object as ConstantExpression;
+            if (constantExpression != null)
+                return new[] { new StepArgument(() => methodCallExpression.Method.Invoke(constantExpression.Value, args.Select(s => s.Value).ToArray())) };
+
+            return new[] { new StepArgument(() => methodCallExpression.Method.Invoke(args.First().Value, args.Skip(1).Select(s => s.Value).ToArray())) };
         }
 
         private static IEnumerable<StepArgument> ExtractArguments<T>(MethodCallExpression methodCallExpression, T value)