1 files changed, 17 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 1ee2546a..590beb7f 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.FunctionSignatureMissingParamTypeError;
 import org.shedlang.compiler.typechecker.errors.FunctionSignatureMissingReturnTypeError;
 import org.shedlang.compiler.types.Effects;
 import org.shedlang.compiler.types.FunctionType;
@@ -11,6 +12,7 @@ import org.shedlang.compiler.util.P;
 
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.*;
@@ -55,4 +57,19 @@ public class TypeCheckerFunctionDefinitionTests {
             () -> typeCheckNamespaceStatement(untyped, context)
         );
     }
+
+    @Test
+    public void whenSignatureIsMissingParamTypeThenErrorIsThrown() {
+        var untyped = UntypedFunctionDefinitionNode.builder()
+            .addPositionalParam("x", Optional.empty())
+            .withReturnType(Untyped.typeLevelReference("Unit"))
+            .build();
+        var context = TypeCheckerContext.EMPTY
+            .enterGlobal(P.map(Map.entry("Unit", Types.metaType(Types.UNIT))));
+
+        assertThrows(
+            FunctionSignatureMissingParamTypeError.class,
+            () -> typeCheckNamespaceStatement(untyped, context)
+        );
+    }
 }