feat(unenv-preset): add native node:repl module support

.changeset/native-node-repl.md

@@ -0,0 +1,5 @@
+---
+"@cloudflare/unenv-preset": minor
+---
+
+Add support for native `node:repl` module when the `enable_nodejs_repl_module` and `experimental` compatibility flags are enabled.

packages/unenv-preset/src/preset.ts

@@ -83,6 +83,7 @@ export function getCloudflarePreset({
 	const sqliteOverrides = getSqliteOverrides(compat);
 	const dgramOverrides = getDgramOverrides(compat);
 	const streamWrapOverrides = getStreamWrapOverrides(compat);
+	const replOverrides = getReplOverrides(compat);
 
 	// "dynamic" as they depend on the compatibility date and flags
 	const dynamicNativeModules = [
@@ -102,6 +103,7 @@ export function getCloudflarePreset({
 		...sqliteOverrides.nativeModules,
 		...dgramOverrides.nativeModules,
 		...streamWrapOverrides.nativeModules,
+		...replOverrides.nativeModules,
 	];
 
 	// "dynamic" as they depend on the compatibility date and flags
@@ -122,6 +124,7 @@ export function getCloudflarePreset({
 		...sqliteOverrides.hybridModules,
 		...dgramOverrides.hybridModules,
 		...streamWrapOverrides.hybridModules,
+		...replOverrides.hybridModules,
 	];
 
 	return {
@@ -760,3 +763,39 @@ function getStreamWrapOverrides({
 				hybridModules: [],
 			};
 }
+
+/**
+ * Returns the overrides for `node:repl` (unenv or workerd)
+ *
+ * The native repl implementation:
+ * - is experimental and has no default enable date
+ * - can be enabled with the "enable_nodejs_repl_module" flag
+ * - can be disabled with the "disable_nodejs_repl_module" flag
+ */
+function getReplOverrides({
+	compatibilityFlags,
+}: {
+	compatibilityDate: string;
+	compatibilityFlags: string[];
+}): { nativeModules: string[]; hybridModules: string[] } {
+	const disabledByFlag = compatibilityFlags.includes(
+		"disable_nodejs_repl_module"
+	);
+
+	const enabledByFlag =
+		compatibilityFlags.includes("enable_nodejs_repl_module") &&
+		compatibilityFlags.includes("experimental");
+
+	const enabled = enabledByFlag && !disabledByFlag;
+
+	// When enabled, use the native `repl` module from workerd
+	return enabled
+		? {
+				nativeModules: ["repl"],
+				hybridModules: [],
+			}
+		: {
+				nativeModules: [],
+				hybridModules: [],
+			};
+}

packages/wrangler/e2e/unenv-preset/preset.test.ts

@@ -598,6 +598,27 @@ const localTestConfigs: TestConfig[] = [
 		// 	},
 		// },
 	],
+	// node:repl (experimental, no default enable date)
+	[
+		// TODO: add test for disabled by date (no date defined yet)
+		// TODO: add test for enabled by date (no date defined yet)
+		{
+			name: "repl enabled by flag",
+			compatibilityDate: "2024-09-23",
+			compatibilityFlags: ["enable_nodejs_repl_module", "experimental"],
+			expectRuntimeFlags: {
+				enable_nodejs_repl_module: true,
+			},
+		},
+		{
+			name: "repl disabled by flag",
+			compatibilityDate: "2024-09-23",
+			compatibilityFlags: ["disable_nodejs_repl_module", "experimental"],
+			expectRuntimeFlags: {
+				enable_nodejs_repl_module: false,
+			},
+		},
+	],
 ].flat() as TestConfig[];
 
 describe.each(localTestConfigs)(

packages/wrangler/e2e/unenv-preset/worker/index.ts

@@ -859,6 +859,43 @@ export const WorkerdTests: Record<string, () => void> = {
 		// `JSStreamSocket` is the default export of `node:_stream_wrap`
 		assertTypeOf(streamWrap, "default", "function");
 	},
+
+	async testRepl() {
+		const repl = await import("node:repl");
+
+		// Common exports (both unenv stub and native workerd)
+		assertTypeOfProperties(repl, {
+			writer: "function",
+			start: "function",
+			Recoverable: "function",
+			REPLServer: "function",
+			builtinModules: "object",
+			_builtinLibs: "object",
+			REPL_MODE_SLOPPY: "symbol",
+			REPL_MODE_STRICT: "symbol",
+		});
+
+		assertTypeOfProperties(repl.default, {
+			writer: "function",
+			start: "function",
+			Recoverable: "function",
+			REPLServer: "function",
+			builtinModules: "object",
+			_builtinLibs: "object",
+			REPL_MODE_SLOPPY: "symbol",
+			REPL_MODE_STRICT: "symbol",
+		});
+
+		// builtinModules should be an array (not in TypeScript types but exported by both unenv and workerd)
+		assert.ok(Array.isArray((repl as any).builtinModules));
+		assert.ok((repl as any).builtinModules.length > 0);
+
+		// Both implementations throw when calling start()
+		assert.throws(
+			() => repl.start(),
+			/not implemented|ERR_METHOD_NOT_IMPLEMENTED/
+		);
+	},
 };
 
 /**