create setCookie function to add a Set-Cookie header on a response

src/setCookie.spec.ts

@@ -0,0 +1,35 @@
+import 'isomorphic-fetch'
+import { describe, expect, it } from 'vitest'
+import { status } from './status'
+import {setCookie} from "./setCookie";
+
+describe('setCookie("name", "value"): Response', () => {
+  it('creates a response with the set-cookie header', async () => {
+    const response = status(200)
+    setCookie(response, "name", "value")
+    expect(response.headers.get("set-cookie")).toBe("name=value")
+  })
+  it('creates a response with the set-cookie header using options', async () => {
+    const response = status(200)
+    setCookie(response, "name", "value", {
+      httpOnly: true,
+      secure: true,
+    })
+    expect(response.headers.get("set-cookie")).toBe("name=value; HttpOnly; Secure")
+  })
+  it('creates a response with the set-cookie header using all options', async () => {
+    const response = status(200)
+    const now = new Date();
+    setCookie(response, "name", "value", {
+      httpOnly: true,
+      secure: true,
+      expires: now,
+      maxAge: 1000,
+      path: "/",
+      domain: "itty.dev",
+      partitioned: true,
+      sameSite: "Strict"
+    })
+    expect(response.headers.get("set-cookie")).toBe(`name=value; Domain=itty.dev; Path=/; HttpOnly; Secure; Expires=${now.toUTCString()}; Max-Age=1000; Partitioned; SameSite=Strict`)
+  })
+})

src/setCookie.ts

@@ -0,0 +1,24 @@
+type CookieOptions = {
+  domain?: string;
+  path?: string;
+  expires?: Date;
+  httpOnly?: boolean;
+  maxAge?: number;
+  partitioned?: boolean;
+  secure?: boolean;
+  sameSite?: "Strict" | "Lax" | "None";
+}
+
+export const setCookie = (response: Response, name: string, value: string, options?: CookieOptions): Response => {
+  response.headers.append("Set-Cookie", `${name}=${value}\
+${options?.domain ? `; Domain=${options.domain}`: ""}\
+${options?.path ? `; Path=${options?.path}`: ""}\
+${options?.httpOnly ? `; HttpOnly`: ""}\
+${options?.secure ? `; Secure`: ""}\
+${options?.expires? `; Expires=${options.expires.toUTCString()}`: ""}\
+${options?.maxAge? `; Max-Age=${options.maxAge}`: ""}\
+${options?.partitioned? `; Partitioned`: ""}\
+${options?.sameSite? `; SameSite=${options.sameSite}`: ""}\
+  `)
+  return response;
+}