Allow function expression to have implicit unit return type

1 files changed, 16 insertions, 0 deletions

diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionExpressionTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionExpressionTests.java
index 85f6b3b7..1d858123 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionExpressionTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionExpressionTests.java
@@ -38,4 +38,20 @@ public class TypeCheckerFunctionExpressionTests {
                 .withType(new FunctionType(List.of(), List.of(), Effects.NONE, Types.UNIT))
         );
     }
+
+    @Test
+    public void whenFunctionHasNoExplicitReturnsThenReturnTypeIsUnit() {
+        var untyped = UntypedFunctionExpressionNode.builder()
+            .withoutReturnType()
+            .build();
+        var context = TypeCheckerContext.EMPTY;
+
+        var typed = typeCheckExpression(untyped, context);
+
+        assertThat(
+            typed.value(),
+            isTypedFunctionExpressionNode()
+                .withType(new FunctionType(List.of(), List.of(), Effects.NONE, Types.UNIT))
+        );
+    }
 }