1 files changed, 16 insertions, 0 deletions
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionDefinitionTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionDefinitionTests.java
index b44b0f96..352e46b6 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionDefinitionTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionDefinitionTests.java
@@ -3,6 +3,7 @@ package org.shedlang.compiler.typechecker;
 import org.junit.jupiter.api.Test;
 import org.shedlang.compiler.ast.untyped.Untyped;
 import org.shedlang.compiler.ast.untyped.UntypedFunctionDefinitionNode;
+import org.shedlang.compiler.typechecker.errors.FunctionSignatureMissingReturnTypeError;
 import org.shedlang.compiler.types.Effects;
 import org.shedlang.compiler.types.FunctionType;
 import org.shedlang.compiler.types.Types;
@@ -11,6 +12,7 @@ import org.shedlang.compiler.util.P;
 import java.util.List;
 import java.util.Map;
 
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.*;
 import static org.shedlang.compiler.typechecker.TypeCheckerTesting.typeCheckNamespaceStatement;
 import static org.zwobble.precisely.AssertThat.assertThat;
@@ -40,4 +42,18 @@ public class TypeCheckerFunctionDefinitionTests {
                 .withType(new FunctionType(List.of(), List.of(), Effects.NONE, Types.UNIT))
         );
     }
+
+    @Test
+    public void whenSignatureIsMissingReturnTypeThenErrorIsThrown() {
+        var untyped = UntypedFunctionDefinitionNode.builder()
+            .withoutReturnType()
+            .build();
+        var context = TypeCheckerContext.EMPTY
+            .enterGlobal(P.map(Map.entry("Unit", Types.metaType(Types.UNIT))));
+
+        assertThrows(
+            FunctionSignatureMissingReturnTypeError.class,
+            () -> typeCheckNamespaceStatement(untyped, context)
+        );
+    }
 }