Protect the Expr field of OldExpr if it is immutable. Add unit test

to check this is being enforced.

1 files changed, 7 insertions, 0 deletions

diff --git a/Source/UnitTests/CoreTests/ExprImmutability.cs b/Source/UnitTests/CoreTests/ExprImmutability.cs
index 68b71083..e13feca7 100644
--- a/Source/UnitTests/CoreTests/ExprImmutability.cs
+++ b/Source/UnitTests/CoreTests/ExprImmutability.cs
@@ -89,6 +89,13 @@ namespace CoreTests
             // Trying to assign the same Type should succeed
             e.Type = BasicType.Bool;
         }
+
+        [Test(), ExpectedException(typeof(InvalidOperationException))]
+        public void ProtectedOldExpr()
+        {
+            var e = new OldExpr(Token.NoToken, Expr.True, /*immutable=*/ true);
+            e.Expr = Expr.False;
+        }
     }
 }