Fix type context for fn (#322)

Author: bterlson

.chronus/changes/fix-type-context-for-fn-2025-9-15-14-5-16.md

@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@alloy-js/typescript"
+---
+
+Fix function return types not being in type context.

packages/typescript/src/components/CallSignature.tsx

@@ -4,6 +4,7 @@ import {
   TypeParameterDescriptor,
 } from "../parameter-descriptor.js";
 import { FunctionDeclaration } from "./FunctionDeclaration.jsx";
+import { TypeRefContext } from "./TypeRefContext.jsx";
 
 export interface CallSignatureProps {
   /**
@@ -57,7 +58,10 @@ export function CallSignature(props: CallSignatureProps) {
     <FunctionDeclaration.Parameters parameters={props.parameters} />
   );
 
-  const sReturnType = props.returnType ? <>: {props.returnType}</> : undefined;
+  const sReturnType =
+    props.returnType ?
+      <TypeRefContext>: {props.returnType}</TypeRefContext>
+    : undefined;
 
   return (
     <>

packages/typescript/test/function-declaration.test.tsx

@@ -2,6 +2,7 @@ import {
   List,
   memberRefkey,
   namekey,
+  Output,
   Props,
   refkey,
   StatementList,
@@ -14,6 +15,8 @@ import {
   FunctionDeclaration,
   InterfaceDeclaration,
   InterfaceMember,
+  SourceFile,
+  TypeDeclaration,
   VarDeclaration,
 } from "../src/index.js";
 import { ParameterDescriptor } from "../src/parameter-descriptor.js";
@@ -386,3 +389,37 @@ describe("symbols", () => {
     `);
   });
 });
+
+it("has parameters and return type in type ref context", () => {
+  const i1 = namekey("iface1");
+  const i2 = namekey("iface2");
+  const template = (
+    <Output>
+      <SourceFile path="test1.ts">
+        <TypeDeclaration name={i1}>any</TypeDeclaration>
+        <hbr />
+        <TypeDeclaration name={i2}>any</TypeDeclaration>
+      </SourceFile>
+
+      <SourceFile path="test2.ts">
+        <FunctionDeclaration
+          name="foo"
+          parameters={[{ name: "a", type: i1 }]}
+          returnType={i2}
+        />
+      </SourceFile>
+    </Output>
+  );
+
+  expect(template).toRenderTo({
+    "test1.ts": `
+      type iface1 = any;
+      type iface2 = any;
+    `,
+    "test2.ts": `
+      import type { iface1, iface2 } from "./test1.js";
+
+      function foo(a: iface1): iface2 {}
+    `,
+  });
+});