From 704531beb6a43e4f515e2a4dd30c65c08bba5aea Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Tue, 7 Nov 2023 20:02:01 +0000
Subject: Use explicit resume type

---
 .../compiler/typechecker/TypeCheckerTryTests.java  | 38 ++++++++++++++++++++++
 1 file changed, 38 insertions(+)

(limited to 'src/test/java')

diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerTryTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerTryTests.java
index 4469979e..f62780d4 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerTryTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerTryTests.java
@@ -351,6 +351,44 @@ public class TypeCheckerTryTests {
         assertThat(error.actual(), equalTo(Types.STRING));
     }
 
+    @Test
+    public void whenHandlerMethodTypeHasNarrowerReturnTypeThanEffectMethodThenNarrowerTypeIsUsedToTypeCheckBody() {
+        var handledEffect = Effects.userDefined(NAMESPACE_NAME, "HandledEffect");
+        var untyped = UntypedTryNode.builder()
+            .withHandledEffect(Untyped.typeLevelReference(handledEffect.name()))
+            .addHandlerMethod(
+                UntypedFunctionDefinitionNode.builder()
+                    .addStatement(Untyped.resume(Untyped.intLiteral(0)))
+                    .withReturnType(Untyped.typeLevelReference("String"))
+                    .withName("mark")
+                    .build()
+            )
+            .build();
+        var context = TypeCheckerContext.EMPTY
+            .addUserDefinedEffectInfo(
+                handledEffect,
+                UserDefinedEffectInfo.builder()
+                    .addField("mark", FunctionType.builder().withReturnType(Types.TOP).build())
+                    .build()
+            )
+            .enterFunction(
+                P.map(
+                    Map.entry("String", Variable.defined(Types.metaType(Types.STRING), VariableType.CONSTANT)),
+                    Map.entry(handledEffect.name(), Variable.defined(Types.effectType(handledEffect), VariableType.CONSTANT))
+                ),
+                Effects.NONE,
+                Optional.empty()
+            );
+
+        var error = assertThrows(
+            UnexpectedTypeError.class,
+            () -> typeCheckExpression(untyped, context)
+        );
+
+        assertThat(error.expected(), equalTo(TypeSets.type(Types.STRING)));
+        assertThat(error.actual(), equalTo(Types.INT));
+    }
+
     @Test
     public void whenHandlerMethodTypeHasEffectThenEffectOfExpressionScopeIsIgnored() {
         var handledEffect = Effects.userDefined(NAMESPACE_NAME, "HandledEffect");
-- 
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