Throw appropriate error when param type cannot be inferred

1 files changed, 36 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 d48ea972..ce2a0570 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionExpressionTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFunctionExpressionTests.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.UntypedFunctionExpressionNode;
+import org.shedlang.compiler.typechecker.errors.FunctionSignatureMissingParamTypeError;
 import org.shedlang.compiler.types.Effects;
 import org.shedlang.compiler.types.FunctionType;
 import org.shedlang.compiler.types.NamedParam;
@@ -13,6 +14,7 @@ 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.*;
 import static org.zwobble.precisely.AssertThat.assertThat;
 import static org.zwobble.precisely.Matchers.isOptionalEmpty;
@@ -78,6 +80,23 @@ public class TypeCheckerFunctionExpressionTests {
     }
 
     @Test
+    public void whenHintIsNotAvailableThenPositionalParamTypeCannotBeInferred() {
+        var untyped = UntypedFunctionExpressionNode.builder()
+            .addPositionalParam("x", Optional.empty())
+            .build();
+        var context = TypeCheckerContext.EMPTY;
+
+        assertThrows(
+            FunctionSignatureMissingParamTypeError.class,
+            () -> TypeChecker.typeCheckExpression(
+                untyped,
+                Optional.empty(),
+                context
+            )
+        );
+    }
+
+    @Test
     public void namedParamTypeCanBeInferredFromHint() {
         var untyped = UntypedFunctionExpressionNode.builder()
             .addNamedParam("x", Optional.empty())
@@ -96,4 +115,21 @@ public class TypeCheckerFunctionExpressionTests {
                 .withType(new FunctionType(List.of(), List.of(new NamedParam("x", Types.STRING)), Effects.NONE, Types.UNIT))
         );
     }
+
+    @Test
+    public void whenHintIsNotAvailableThenNamedParamTypeCannotBeInferred() {
+        var untyped = UntypedFunctionExpressionNode.builder()
+            .addNamedParam("x", Optional.empty())
+            .build();
+        var context = TypeCheckerContext.EMPTY;
+
+        assertThrows(
+            FunctionSignatureMissingParamTypeError.class,
+            () -> TypeChecker.typeCheckExpression(
+                untyped,
+                Optional.empty(),
+                context
+            )
+        );
+    }
 }