From 431af33dec8c0e22868696c659021636af9c4b82 Mon Sep 17 00:00:00 2001
From: Dario Piotrowicz <dario@cloudflare.com>
Date: Mon, 5 Feb 2024 18:55:19 +0000
Subject: [PATCH] add a `cf` field to the `getBindingsProxy` result

---
 .changeset/strong-otters-hope.md              | 16 ++++++++
 .../tests/get-bindings-proxy.cf.test.ts       | 38 +++++++++++++++++++
 .../src/api/integrations/bindings/index.ts    |  6 +++
 3 files changed, 60 insertions(+)
 create mode 100644 .changeset/strong-otters-hope.md
 create mode 100644 fixtures/get-bindings-proxy/tests/get-bindings-proxy.cf.test.ts

diff --git a/.changeset/strong-otters-hope.md b/.changeset/strong-otters-hope.md
new file mode 100644
index 000000000000..2040912bf94a
--- /dev/null
+++ b/.changeset/strong-otters-hope.md
@@ -0,0 +1,16 @@
+---
+"wrangler": minor
+---
+
+feature: add a `cf` field to the `getBindingsProxy` result
+
+Add a new `cf` filed to the `getBindingsProxy` result that people can use to mock the production
+`cf` (`IncomingRequestCfProperties`) object.
+
+Example:
+
+```ts
+const { cf } = await getBindingsProxy();
+
+console.log(`country = ${cf.country} ; colo = ${cf.colo}`); // logs 'country = GB ; colo = LHR'
+```
diff --git a/fixtures/get-bindings-proxy/tests/get-bindings-proxy.cf.test.ts b/fixtures/get-bindings-proxy/tests/get-bindings-proxy.cf.test.ts
new file mode 100644
index 000000000000..d52d379559d5
--- /dev/null
+++ b/fixtures/get-bindings-proxy/tests/get-bindings-proxy.cf.test.ts
@@ -0,0 +1,38 @@
+import { describe, expect, it } from "vitest";
+import { getBindingsProxy } from "./shared";
+
+describe("getBindingsProxy - cf", () => {
+	it("should provide mock data", async () => {
+		const { cf, dispose } = await getBindingsProxy();
+		try {
+			expect(cf).toMatchObject({
+				colo: "DFW",
+				city: "Austin",
+				regionCode: "TX",
+			});
+		} finally {
+			await dispose();
+		}
+	});
+
+	it("should match the production runtime cf object", async () => {
+		const { cf, dispose } = await getBindingsProxy();
+		try {
+			expect(cf.constructor.name).toBe("Object");
+
+			expect(() => {
+				cf.city = "test city";
+			}).toThrowError(
+				"Cannot assign to read only property 'city' of object '#<Object>'"
+			);
+			expect(cf.city).not.toBe("test city");
+
+			expect(() => {
+				cf.newField = "test new field";
+			}).toThrowError("Cannot add property newField, object is not extensible");
+			expect("newField" in cf).toBe(false);
+		} finally {
+			await dispose();
+		}
+	});
+});
diff --git a/packages/wrangler/src/api/integrations/bindings/index.ts b/packages/wrangler/src/api/integrations/bindings/index.ts
index 487dae15f810..20a9ce137bfb 100644
--- a/packages/wrangler/src/api/integrations/bindings/index.ts
+++ b/packages/wrangler/src/api/integrations/bindings/index.ts
@@ -41,6 +41,11 @@ export type BindingsProxy<Bindings = Record<string, unknown>> = {
 	 * Object containing the various proxies
 	 */
 	bindings: Bindings;
+	/**
+	 * Mock of the context object that Workers received in their request handler, all the object's methods are no-op
+	 */
+	// eslint-disable-next-line @typescript-eslint/no-explicit-any
+	cf: Record<string, any>;
 	/**
 	 * Mock of the context object that Workers received in their request handler, all the object's methods are no-op
 	 */
@@ -93,6 +98,7 @@ export async function getBindingsProxy<Bindings = Record<string, unknown>>(
 			...vars,
 			...bindings,
 		},
+		cf: Object.freeze(await mf.getCf()),
 		ctx: new ExecutionContext(),
 		caches: new CacheStorage(),
 		dispose: () => mf.dispose(),