Test coverage for checked multi-line assignments

Author: SteveWilkes

ReadableExpressions.UnitTests/WhenTranslatingAssignments.cs

@@ -54,14 +54,42 @@ public void ShouldTranslateASubtractionAssignment()
         }
 
         [TestMethod]
-        public void ShouldTranslateACheckedSubtractionAssignment()
+        public void ShouldTranslateAMultiLineCheckedSubtractionAssignment()
         {
             var intVariable = Expression.Variable(typeof(int), "i");
-            var substractOneAndAssign = Expression.SubtractAssignChecked(intVariable, Expression.Constant(1));
+
+            Expression<Action> consoleRead = () => Console.Read();
+
+            var variableOne = Expression.Variable(typeof(int), "one");
+            var variableTwo = Expression.Variable(typeof(int), "two");
+
+            var variableOneAssignment = Expression.Assign(variableOne, consoleRead.Body);
+            var variableTwoAssignment = Expression.Assign(variableTwo, consoleRead.Body);
+
+            var variableOnePlusTwo = Expression.Add(variableOne, variableTwo);
+
+            var valueBlock = Expression.Block(
+                new[] { variableOne, variableTwo },
+                variableOneAssignment,
+                variableTwoAssignment,
+                variableOnePlusTwo);
+
+            var substractOneAndAssign = Expression.SubtractAssignChecked(intVariable, valueBlock);
 
             var translated = substractOneAndAssign.ToReadableString();
 
-            Assert.AreEqual("checked { i -= 1 }", translated);
+            const string EXPECTED = @"
+checked
+{
+    i -= 
+    {
+        var one = Console.Read();
+        var two = Console.Read();
+        return (one + two);
+    }
+}";
+
+            Assert.AreEqual(EXPECTED.TrimStart(), translated);
         }
 
         [TestMethod]

ReadableExpressions/Extensions/InternalExpressionExtensions.cs

@@ -28,14 +28,21 @@ public static bool IsReturnable(this Expression expression)
                 case ExpressionType.Constant:
                     return !expression.IsComment();
 
+                case ExpressionType.Add:
+                case ExpressionType.AddChecked:
                 case ExpressionType.Call:
                 case ExpressionType.Conditional:
                 case ExpressionType.Convert:
                 case ExpressionType.ConvertChecked:
                 case ExpressionType.Default:
+                case ExpressionType.Divide:
                 case ExpressionType.Invoke:
                 case ExpressionType.MemberAccess:
+                case ExpressionType.Multiply:
+                case ExpressionType.MultiplyChecked:
                 case ExpressionType.Parameter:
+                case ExpressionType.Subtract:
+                case ExpressionType.SubtractChecked:
                     return true;
             }