From 38f3a0a74a6f6b8dd4a3341d76a4e3db7872e084 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sun, 5 Nov 2023 12:45:05 +0000
Subject: Prevent capturing of var

---
 .../typechecker/TypeCheckerFunctionBodyTests.java  | 23 ++++++++++++++++++++++
 1 file changed, 23 insertions(+)

(limited to 'src/test/java')

diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionBodyTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionBodyTests.java
index 37c5d6dd..c6abd22a 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionBodyTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionBodyTests.java
@@ -3,11 +3,13 @@ package org.shedlang.compiler.typechecker;
 import org.junit.jupiter.api.Test;
 import org.shedlang.compiler.ast.untyped.Untyped;
 import org.shedlang.compiler.ast.untyped.UntypedCallNode;
+import org.shedlang.compiler.typechecker.errors.CannotCaptureVarError;
 import org.shedlang.compiler.typechecker.errors.DuplicateVariableNameError;
 import org.shedlang.compiler.typechecker.errors.UnexpectedTypeError;
 import org.shedlang.compiler.typechecker.typesets.TypeSets;
 import org.shedlang.compiler.types.Effects;
 import org.shedlang.compiler.types.FunctionType;
+import org.shedlang.compiler.types.NamespaceName;
 import org.shedlang.compiler.types.Types;
 import org.shedlang.compiler.util.P;
 
@@ -449,6 +451,27 @@ public class TypeCheckerFunctionBodyTests {
         );
     }
 
+    @Test
+    public void varsCannotBeCaptured() {
+        var untyped = Untyped.block(List.of(
+            Untyped.expressionStatement(Untyped.reference("x"))
+        ));
+        var signature = PartialFunctionSignature.builder()
+            .withReturnType(Types.UNIT)
+            .build();
+        var context = TypeCheckerContext.EMPTY
+            .enterNamespace(NamespaceName.of("Example"), P.map(
+                Map.entry("x", Variable.defined(Types.STRING, VariableType.VAR))
+            ));
+
+        var error = assertThrows(
+            CannotCaptureVarError.class,
+            () -> typeCheckFunctionBody(untyped, signature, context)
+        );
+
+        assertThat(error.name(), equalTo("x"));
+    }
+
     @Test
     public void boundVariablesAreSet() {
         var untyped = Untyped.block(List.of(
-- 
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