fix: config preview_urls defaults to undefined (falsy) instead of true

We want preview_urls to be opt-in, rather than opt-out. For this reason
its default value will be falsy.

Author: danielrs

.changeset/ready-banks-repair.md

@@ -0,0 +1,8 @@
+---
+"wrangler": minor
+---
+
+Beta feature preview_urls is now disabled by default.
+
+This change makes preview_urls disabled by default when it's not provided, making
+the feature opt-in instead of opt-out.

packages/wrangler/src/__tests__/config/configuration.test.ts

@@ -130,7 +130,7 @@ describe("normalizeAndValidateConfig()", () => {
 			wasm_modules: undefined,
 			data_blobs: undefined,
 			workers_dev: undefined,
-			preview_urls: true,
+			preview_urls: undefined,
 			zone_id: undefined,
 			no_bundle: undefined,
 			minify: undefined,

packages/wrangler/src/__tests__/deploy.test.ts

@@ -2116,7 +2116,7 @@ Update them to point to this script instead?`,
 				});
 				await mockAUSRequest([]);
 				mockSubDomainRequest();
-				mockUpdateWorkerSubdomain({ enabled: false, previews_enabled: true });
+				mockUpdateWorkerSubdomain({ enabled: false, previews_enabled: false });
 				mockUploadWorkerRequest({
 					expectedAssets: {
 						jwt: "<<aus-completion-token>>",

packages/wrangler/src/__tests__/helpers/mock-workers-subdomain.ts

@@ -36,7 +36,7 @@ export function mockSubDomainRequest(
 /** Create a mock handler to fetch the  <script>.<user>.workers.dev subdomain status*/
 export function mockGetWorkerSubdomain({
 	enabled,
-	previews_enabled = true,
+	previews_enabled = false,
 	env,
 	legacyEnv = false,
 	expectedScriptName = "test-name" + (legacyEnv && env ? `-${env}` : ""),
@@ -73,7 +73,7 @@ export function mockGetWorkerSubdomain({
 /** Create a mock handler to toggle a <script>.<user>.workers.dev subdomain status */
 export function mockUpdateWorkerSubdomain({
 	enabled,
-	previews_enabled = true,
+	previews_enabled = false,
 	env,
 	legacyEnv = false,
 	expectedScriptName = "test-name",

packages/wrangler/src/config/config.ts

@@ -346,7 +346,7 @@ export const defaultWranglerConfig: Config = {
 	preserve_file_names: undefined,
 	base_dir: undefined,
 	workers_dev: undefined,
-	preview_urls: true,
+	preview_urls: undefined,
 	route: undefined,
 	routes: undefined,
 	tsconfig: undefined,

packages/wrangler/src/config/environment.ts

@@ -312,7 +312,7 @@ interface EnvironmentInheritable {
 	 * Whether we use <version>-<name>.<subdomain>.workers.dev to
 	 * serve Preview URLs for your Worker.
 	 *
-	 * @default true
+	 * @default false
 	 * @inheritable
 	 */
 	preview_urls: boolean | undefined;

packages/wrangler/src/config/validation.ts

@@ -1059,7 +1059,7 @@ function normalizeAndValidateEnvironment(
 		rawEnv,
 		"preview_urls",
 		isBoolean,
-		true
+		undefined
 	);
 
 	const build = normalizeAndValidateBuild(