Add header + caching to runtime type generation (#6329)

* Add header + caching to runtime type generation

* Create perfect-pens-work.md

* Update packages/wrangler/src/type-generation/runtime/index.ts

Co-authored-by: Andy Jessop <andrewdjessop@gmail.com>

---------

Co-authored-by: Andy Jessop <andrewdjessop@gmail.com>

.changeset/perfect-pens-work.md

@@ -0,0 +1,5 @@
+---
+"wrangler": patch
+---
+
+chore: Cache generated runtime types

packages/wrangler/e2e/types.test.ts

@@ -1,5 +1,5 @@
 import { existsSync } from "node:fs";
-import { readFile } from "node:fs/promises";
+import { readFile, writeFile } from "node:fs/promises";
 import path from "node:path";
 import { describe, expect, it } from "vitest";
 import { dedent } from "../src/utils/dedent";
@@ -10,7 +10,7 @@ const seed = {
 		name = "test-worker"
 		main = "src/index.ts"
 		compatibility_date = "2023-01-01"
-		compatibility_flags = ["nodejs_compat"]
+		compatibility_flags = ["nodejs_compat", "no_global_navigator"]
 	`,
 	"src/index.ts": dedent`
 		export default {
@@ -150,4 +150,38 @@ describe("types", () => {
 		expect(output.stderr).toBe("");
 		expect(output.status).toBe(0);
 	});
+	it("should include header with version information in the generated types", async () => {
+		const helper = new WranglerE2ETestHelper();
+		await helper.seed(seed);
+		await helper.run(`wrangler types --x-include-runtime="./types.d.ts"`);
+
+		const file = (
+			await readFile(path.join(helper.tmpPath, "./types.d.ts"))
+		).toString();
+
+		expect(file.split("\n")[0]).match(
+			/\/\/ Runtime types generated with workerd@1\.\d+\.\d \d\d\d\d-\d\d-\d\d ([a-z_]+,?)*/
+		);
+	});
+	it("should not regenerate types if the header matches", async () => {
+		const helper = new WranglerE2ETestHelper();
+		await helper.seed(seed);
+		await helper.run(`wrangler types --x-include-runtime`);
+
+		const runtimeTypesFile = path.join(
+			helper.tmpPath,
+			"./.wrangler/types/runtime.d.ts"
+		);
+		const file = (await readFile(runtimeTypesFile)).toString();
+
+		const header = file.split("\n")[0];
+
+		await writeFile(runtimeTypesFile, header + "\n" + "SOME_RANDOM_DATA");
+
+		await helper.run(`wrangler types --x-include-runtime`);
+
+		const file2 = (await readFile(runtimeTypesFile)).toString();
+
+		expect(file2.split("\n")[1]).toBe("SOME_RANDOM_DATA");
+	});
 });

packages/wrangler/src/type-generation/index.ts

@@ -489,8 +489,7 @@ function writeDTSFile({
 		fs.writeFileSync(
 			path,
 			[
-				`// Generated by Wrangler on ${new Date()}`,
-				`// by running \`${wranglerCommandUsed}\``,
+				`// Generated by Wrangler by running \`${wranglerCommandUsed}\``,
 				"",
 				combinedTypeStrings,
 			].join("\n")

packages/wrangler/src/type-generation/runtime/index.ts

@@ -1,6 +1,8 @@
 import { readFileSync } from "fs";
-import { writeFile } from "fs/promises";
+import { readFile, writeFile } from "fs/promises";
 import { Miniflare } from "miniflare";
+import { version } from "workerd";
+import { logger } from "../../logger";
 import { ensureDirectoryExists } from "../../utils/filesystem";
 import type { Config } from "../../config/config";
 
@@ -47,6 +49,20 @@ export async function generateRuntimeTypes({
 
 	await ensureDirectoryExists(outFile);
 
+	const header = `// Runtime types generated with workerd@${version} ${compatibility_date} ${compatibility_flags.join(",")}`;
+
+	try {
+		const existingTypes = await readFile(outFile, "utf8");
+		if (existingTypes.split("\n")[0] === header) {
+			logger.debug("Using cached runtime types: ", header);
+			return { outFile };
+		}
+	} catch (e) {
+		if ((e as { code: string }).code !== "ENOENT") {
+			throw e;
+		}
+	}
+
 	const types = await generate({
 		compatibilityDate: compatibility_date,
 		// Ignore nodejs compat flags as there is currently no mechanism to generate these dynamically.
@@ -55,7 +71,7 @@ export async function generateRuntimeTypes({
 		),
 	});
 
-	await writeFile(outFile, types, "utf8");
+	await writeFile(outFile, `${header}\n${types}`, "utf8");
 
 	return {
 		outFile,

packages/wrangler/src/workerd.d.ts

@@ -0,0 +1,6 @@
+declare module "workerd" {
+	const path: string;
+	export default path;
+	export const compatibilityDate: string;
+	export const version: string;
+}