Add test for res.redirect in API route

Test that res.redirect works in API routes.
Documentation: https://nextjs.org/docs/api-routes/response-helpers

Author: afzalsayed96

cypress/fixtures/pages/api/redirect.js

@@ -0,0 +1,6 @@
+export default async function preview(req, res) {
+  const { query } = req;
+  const { to } = query;
+
+  res.redirect(`/shows/${to}`);
+}

cypress/integration/default_spec.js

@@ -526,6 +526,14 @@ describe("API endpoint", () => {
       );
     });
   });
+
+  it("redirects with res.redirect", () => {
+    cy.visit("/api/redirect?to=999");
+
+    cy.url().should("include", "/shows/999");
+    cy.get("h1").should("contain", "Show #999");
+    cy.get("p").should("contain", "Flash Gordon");
+  });
 });
 
 describe("Preview Mode", () => {