Throw exception if assigning value of wrong type

1 files changed, 15 insertions, 0 deletions

diff --git a/src/test/java/org/zwobble/couscous/tests/interpreter/InterpreterTests.java b/src/test/java/org/zwobble/couscous/tests/interpreter/InterpreterTests.java
index 46b30d9..6fe799f 100644
--- a/src/test/java/org/zwobble/couscous/tests/interpreter/InterpreterTests.java
+++ b/src/test/java/org/zwobble/couscous/tests/interpreter/InterpreterTests.java
@@ -11,9 +11,11 @@ import org.zwobble.couscous.ast.MethodNode;
 import org.zwobble.couscous.ast.ReturnNode;
 import org.zwobble.couscous.interpreter.Interpreter;
 import org.zwobble.couscous.interpreter.UnboundVariable;
+import org.zwobble.couscous.interpreter.UnexpectedValueType;
 import org.zwobble.couscous.interpreter.VariableNotInScope;
 import org.zwobble.couscous.interpreter.WrongNumberOfArguments;
 import org.zwobble.couscous.values.ConcreteType;
+import org.zwobble.couscous.values.IntegerValue;
 import org.zwobble.couscous.values.InterpreterValue;
 import org.zwobble.couscous.values.StringValue;
 
@@ -82,6 +84,19 @@ public class InterpreterTests {
     }
     
     @Test
+    public void errorIfTryingToAssignValueOfWrongTypeToVariable() {
+        val arg = new FormalArgumentNode(42, StringValue.REF, "x");
+        val method = staticMethod("hello")
+            .argument(arg)
+            .statement(new ExpressionStatementNode(new Assignment(reference(arg), literal(0))));
+
+        val exception = assertThrows(UnexpectedValueType.class,
+            () -> runMethod(method, new StringValue("")));
+        
+        assertEquals(new UnexpectedValueType(StringValue.REF, IntegerValue.REF), exception);
+    }
+    
+    @Test
     public void canDeclareVariable() {
         val localVariableDeclaration = localVariableDeclaration(
             42, StringValue.REF, "x", LiteralNode.literal("[initial value]"));