Check that variable is declared and defined in same scope

1 files changed, 17 insertions, 0 deletions

diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerContextTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerContextTests.java
index 2be22340..13f2486b 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerContextTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerContextTests.java
@@ -2,6 +2,7 @@ package org.shedlang.compiler.typechecker;
 
 import org.junit.jupiter.api.Test;
 import org.shedlang.compiler.sources.Sources;
+import org.shedlang.compiler.typechecker.errors.CannotDefineVariableDeclaredInOuterScopeError;
 import org.shedlang.compiler.typechecker.errors.UnknownVariableError;
 import org.shedlang.compiler.typechecker.errors.VariableIsAlreadyDefinedError;
 import org.shedlang.compiler.types.Types;
@@ -58,4 +59,20 @@ public class TypeCheckerContextTests {
 
         assertThat(error.variableName(), equalTo("x"));
     }
+
+    @Test
+    public void givenVariableIsBoundInOuterScopeWhenVariableIsDefinedThenErrorIsThrown() {
+        var context = TypeCheckerContext.EMPTY
+            .enterNamespace(P.map(
+                Map.entry("x", TypeCheckerContext.undefined())
+            ))
+            .enterNamespace(P.map());
+
+        var error = assertThrows(
+            CannotDefineVariableDeclaredInOuterScopeError.class,
+            () -> context.define("x", Types.STRING, Sources.NULL)
+        );
+
+        assertThat(error.variableName(), equalTo("x"));
+    }
 }