refactor: rewrite ResponseBody to extract from a ResponseMap with no-…

…content support

src/api-spec.ts

@@ -1,8 +1,6 @@
 import type {
   OperationRequestBodyContent,
   PathsWithMethod,
-  ResponseContent,
-  ResponseObjectMap,
 } from "openapi-typescript-helpers";
 import type {
   ConvertToStringified,
@@ -68,8 +66,11 @@ export type RequestBody<
   ? OperationRequestBodyContent<ApiSpec[Path][Method]>
   : never;
 
-/** Extract the response body of a given path and method from an api spec. */
-export type ResponseBody<
+/**
+ * Extract a response map of a given path and method from an api spec.
+ * A response map has the shape of (status -> media-type -> body).
+ */
+export type ResponseMap<
   ApiSpec extends AnyApiSpec,
   Path extends keyof ApiSpec,
   Method extends HttpMethod,
@@ -78,21 +79,33 @@ export type ResponseBody<
       // eslint-disable-next-line @typescript-eslint/no-explicit-any
       responses: any;
     }
-    ? ConvertNoContent<
-        MapToValues<
-          ResolvedObjectUnion<
-            ResponseContent<
-              MapToValues<ResponseObjectMap<ApiSpec[Path][Method]>>
-            >
-          >
-        >
-      >
+    ? {
+        [Status in keyof ApiSpec[Path][Method]["responses"]]: ConvertContent<
+          ApiSpec[Path][Method]["responses"][Status]
+        >["content"];
+      }
     : never
   : never;
 
+/** Extract the response body of a given path and method from an api spec. */
+export type ResponseBody<
+  ApiSpec extends AnyApiSpec,
+  Path extends keyof ApiSpec,
+  Method extends HttpMethod,
+> = MapToValues<
+  ResolvedObjectUnion<MapToValues<ResponseMap<ApiSpec, Path, Method>>>
+>;
+
 /**
  * OpenAPI-TS generates "no content" with `content?: never`.
  * However, `new Response().body` is `null` and strictly typing no-content in
- * MSW requires `null`. Therefore, this helper maps no-content to `null`.
+ * MSW requires `null`. Therefore, this helper ensures that "no-content"
+ * can be mapped to null when typing the response body.
  */
-type ConvertNoContent<Content> = [Content] extends [never] ? null : Content;
+type ConvertContent<Content> =
+  Required<Content> extends { content: never }
+    ? { content: { "no-content": null } }
+    : // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      Content extends { content: any }
+      ? Content
+      : never;

test/fixtures/no-content.api.yml

@@ -18,3 +18,31 @@ paths:
       responses:
         204:
           description: No Content
+  /no-content-resource:
+    get:
+      summary: Get Resource With No Content
+      operationId: getResourceNoContent
+      responses:
+        200:
+          description: Success
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Resource"
+        204:
+          description: NoContent
+components:
+  schemas:
+    Resource:
+      type: object
+      required:
+        - id
+        - name
+        - value
+      properties:
+        id:
+          type: string
+        name:
+          type: string
+        value:
+          type: integer

test/no-content.test-d.ts

@@ -22,4 +22,15 @@ describe("Given an OpenAPI schema endpoint with no-content", () => {
     response.not.toEqualTypeOf<Response>();
     response.toEqualTypeOf<StrictResponse<null>>();
   });
+
+  test("When a endpoint with NoContent response is mocked, Then the no-content option is included in the response union", async () => {
+    type Endpoint = typeof http.get<"/no-content-resource">;
+    const resolver = expectTypeOf<Endpoint>().parameter(1);
+    const response = resolver.returns.extract<Response>();
+
+    response.not.toEqualTypeOf<Response>();
+    response.toEqualTypeOf<
+      StrictResponse<{ id: string; name: string; value: number } | null>
+    >();
+  });
 });