Merge pull request #12 from thefrontside/cl/redirect-response

✨ respond with redirects

Author: cowboyd

lib/middleware/http-responses.ts

@@ -22,6 +22,21 @@ export function* respondNotFound(): Operation<never> {
   throw new Error("This code is unreachable, but TypeScript don't know.");
 }
 
+export interface RedirectOptions {
+  permanent?: boolean;
+}
+
+export function* respondRedirect(
+  url: string | URL,
+  options: RedirectOptions = {},
+): Operation<never> {
+  let status = options.permanent ? 308 : 307;
+  let respond = yield* ResponseContext;
+  respond(Response.redirect(url, status));
+  yield* suspend();
+  throw new Error("This code is unreachable, but TypeScript don't know.");
+}
+
 export function httpResponsesMiddleware(): HTTPMiddleware {
   return function* httpResponses(request, next): Operation<Response> {
     try {

test/middleware/http-responses.test.ts

@@ -1,5 +1,10 @@
 import { describe, expect, it } from "../suite.ts";
-import { concat, httpResponsesMiddleware, respondNotFound } from "../../mod.ts";
+import {
+  concat,
+  httpResponsesMiddleware,
+  respondNotFound,
+  respondRedirect,
+} from "../../mod.ts";
 
 describe("http responses middleware", () => {
   it("can short circuit a middleware stack with a 404", function* () {
@@ -18,4 +23,46 @@ describe("http responses middleware", () => {
 
     expect(response.status).toEqual(404);
   });
+
+  it("can short circuit a middleware stack with a temporary redirect", function* () {
+    let handler = concat(
+      httpResponsesMiddleware(),
+      function* () {
+        return yield* respondRedirect("https://localhost/other.html");
+      },
+    );
+
+    let request = new Request("http://localhost/test.html");
+
+    let response = yield* handler(request, function* () {
+      throw new Error(`should not reach here.`);
+    });
+
+    expect(response.status).toEqual(307);
+    expect(response.headers.get("location")).toEqual(
+      "https://localhost/other.html",
+    );
+  });
+
+  it("can short circuit a middleware stack with a permanent redirect", function* () {
+    let handler = concat(
+      httpResponsesMiddleware(),
+      function* () {
+        return yield* respondRedirect("https://localhost/other.html", {
+          permanent: true,
+        });
+      },
+    );
+
+    let request = new Request("http://localhost/test.html");
+
+    let response = yield* handler(request, function* () {
+      throw new Error(`should not reach here.`);
+    });
+
+    expect(response.status).toEqual(308);
+    expect(response.headers.get("location")).toEqual(
+      "https://localhost/other.html",
+    );
+  });
 });