Fix update of top lexical context

1 files changed, 24 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 7a2d7d71..a9198b86 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerContextTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerContextTests.java
@@ -76,6 +76,30 @@ public class TypeCheckerContextTests {
     }
 
     @Test
+    public void definingVariableOnlyAffectsTopMostLexicalContext() {
+        var context = TypeCheckerContext.EMPTY
+            .enterNamespace(P.map(
+                Map.entry("x", TypeCheckerContext.undefined()),
+                Map.entry("y", TypeCheckerContext.undefined())
+            ));
+
+        context = context.enterBlock(P.map(
+            Map.entry("x", TypeCheckerContext.undefined())
+        ));
+        context = context.define("x", Types.STRING, Sources.NULL);
+        assertThat(
+            context.runtimeLookup("x", Sources.NULL).value(),
+            isOptionalOf(equalTo(TypeCheckerContext.defined(Types.STRING)))
+        );
+
+        context = context.exit();
+        assertThat(
+            context.runtimeLookup("x", Sources.NULL).value(),
+            isOptionalOf(equalTo(TypeCheckerContext.undefined()))
+        );
+    }
+
+    @Test
     public void runtimeLookupUpdatesFreeVariablesUntilLexicalContextInWhichVariableIsDefined() {
         var context = TypeCheckerContext.EMPTY
             .enterBlock(P.map())