1 files changed, 9 insertions, 0 deletions
diff --git a/src/test/java/org/zwobble/couscous/tests/interpreter/EvaluatorTests.java b/src/test/java/org/zwobble/couscous/tests/interpreter/EvaluatorTests.java
index 5ebb948..d4cb2f1 100644
--- a/src/test/java/org/zwobble/couscous/tests/interpreter/EvaluatorTests.java
+++ b/src/test/java/org/zwobble/couscous/tests/interpreter/EvaluatorTests.java
@@ -6,6 +6,7 @@ import org.zwobble.couscous.ast.TernaryConditionalNode;
 import org.zwobble.couscous.interpreter.ConditionMustBeBoolean;
 import org.zwobble.couscous.interpreter.Environment;
 import org.zwobble.couscous.interpreter.NoSuchMethod;
+import org.zwobble.couscous.interpreter.UnexpectedValueType;
 import org.zwobble.couscous.interpreter.WrongNumberOfArguments;
 import org.zwobble.couscous.values.IntegerValue;
 import org.zwobble.couscous.values.StringValue;
@@ -82,6 +83,14 @@ public class EvaluatorTests {
         assertEquals(new WrongNumberOfArguments(2, 1), exception);
     }
     
+    @Test
+    public void errorIfArgumentIsWrongType() {
+        val exception = assertThrows(UnexpectedValueType.class,
+            () -> eval(emptyEnvironment(),
+                methodCall(literal("hello"), "substring", literal(0), literal(""))));
+        assertEquals(new UnexpectedValueType(IntegerValue.TYPE, StringValue.TYPE), exception);
+    }
+    
     private static Environment emptyEnvironment() {
         return new Environment(ImmutableMap.of());
     }