From 73915b6f89e4551575b349d5fda6bacf2b578288 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Tue, 7 Nov 2023 18:57:50 +0000
Subject: Handle handler method signature properly

---
 .../compiler/typechecker/TypeCheckerTryTests.java  | 82 ++++++++++++++++++++++
 1 file changed, 82 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 2a335d20..4469979e 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerTryTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerTryTests.java
@@ -313,6 +313,88 @@ public class TypeCheckerTryTests {
         );
     }
 
+    @Test
+    public void whenHandlerMethodTypeHasWrongReturnTypeThenErrorIsThrown() {
+        var handledEffect = Effects.userDefined(NAMESPACE_NAME, "HandledEffect");
+        var untyped = UntypedTryNode.builder()
+            .withHandledEffect(Untyped.typeLevelReference(handledEffect.name()))
+            .addHandlerMethod(
+                UntypedFunctionDefinitionNode.builder()
+                    .addStatement(Untyped.resume())
+                    .withReturnType(Untyped.typeLevelReference("String"))
+                    .withName("mark")
+                    .build()
+            )
+            .build();
+        var context = TypeCheckerContext.EMPTY
+            .addUserDefinedEffectInfo(
+                handledEffect,
+                UserDefinedEffectInfo.builder()
+                    .addField("mark", FunctionType.builder().withReturnType(Types.UNIT).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.UNIT)));
+        assertThat(error.actual(), equalTo(Types.STRING));
+    }
+
+    @Test
+    public void whenHandlerMethodTypeHasEffectThenEffectOfExpressionScopeIsIgnored() {
+        var handledEffect = Effects.userDefined(NAMESPACE_NAME, "HandledEffect");
+        var untyped = UntypedTryNode.builder()
+            .withHandledEffect(Untyped.typeLevelReference(handledEffect.name()))
+            .addHandlerMethod(
+                UntypedFunctionDefinitionNode.builder()
+                    .withName("effectField")
+                    .withEffect(Untyped.typeLevelReference("Pure"))
+                    .addStatement(Untyped.resume(
+                        UntypedCallNode.builder()
+                            .withReceiver(Untyped.reference("f"))
+                            .withHasEffects(true)
+                            .build()
+                    ))
+                    .build()
+            )
+            .build();
+        var context = TypeCheckerContext.EMPTY
+            .enterFunction(
+                P.map(
+                    Map.entry(handledEffect.name(), Variable.defined(Types.effectType(handledEffect), VariableType.CONSTANT)),
+                    Map.entry("Pure", Variable.defined(Types.effectType(Effects.NONE), VariableType.CONSTANT)),
+                    Map.entry("f", Variable.defined(FunctionType.builder().withEffect(Effects.IO).build(), VariableType.VAL))
+                ),
+                Effects.IO,
+                Optional.empty()
+            )
+            .addUserDefinedEffectInfo(
+                handledEffect,
+                UserDefinedEffectInfo.builder()
+                    .addField("effectField", FunctionType.builder().withReturnType(Types.UNIT).build())
+                    .build()
+            );
+
+        var error = assertThrows(
+            UnexpectedEffectError.class,
+            () -> typeCheckExpression(untyped, context)
+        );
+
+        assertThat(error.allowed(), equalTo(Effects.NONE));
+        assertThat(error.actual(), equalTo(Effects.IO));
+    }
+
     @Test
     public void whenEffectIsNotAllowedInExpressionScopeAndIsNotHandledEffectThenEffectIsNotAllowedInHandlerScope() {
         var handledEffect = Effects.userDefined(NAMESPACE_NAME, "HandledEffect");
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