Support inferring return type from single return statement

1 files changed, 19 insertions, 0 deletions

diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionBodyTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionBodyTests.java
index 5bc73325..5e80c9a0 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionBodyTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionBodyTests.java
@@ -268,6 +268,25 @@ public class TypeCheckerFunctionBodyTests {
     }
 
     @Test
+    public void givenNoExplicitReturnTypeWhenThereIsOneExplicitReturnThenReturnTypeIsTypeOfReturnExpression() {
+        var untyped = Untyped.block(List.of(
+            Untyped.functionReturn(Untyped.stringLiteral(""))
+        ));
+        var signature = TypedFunctionSignatureNode.builder()
+            .withoutReturnType()
+            .build();
+        var context = TypeCheckerContext.EMPTY;
+
+        var typed = typeCheckFunctionBody(untyped, signature, context);
+
+        assertThat(
+            typed.value(),
+            isTypedFunctionBodyNode()
+                .withType(Types.STRING)
+        );
+    }
+
+    @Test
     public void freeVariablesIncludeVariablesReferencedInFunctionButDefinedOutsideOfFunction() {
         var untyped = Untyped.block(List.of(
             Untyped.expressionStatement(Untyped.reference("y"))