fix(wrangler): enforce Pages config validation around DOs (#5666)

Today Pages cannot deploy Durable Objects itself. For this
reason it is mandatory that when declaring Durable Objects
bindings in the config file, the `script_name` is specified.
We are currently not failing validation if `script_name` is
not specified but we should. This commit fixes that.

Co-authored-by: Carmen Popoviciu <cpopoviciu@cloudflare.com>

.changeset/new-dolphins-dress.md

@@ -0,0 +1,8 @@
+---
+"wrangler": minor
+---
+
+fix: Fix Pages config validation around Durable Objects
+
+Today Pages cannot deploy Durable Objects itself. For this reason it is mandatory that when declaring Durable Objects bindings in the config file, the `script_name` is specified. We are currently not failing validation if
+`script_name` is not specified but we should. These changes fix that.

packages/wrangler/src/__tests__/config-validation-pages.test.ts

@@ -139,7 +139,11 @@ describe("validatePagesConfig()", () => {
 					vars: { FOO: "foo" },
 					durable_objects: {
 						bindings: [
-							{ name: "TEST_DO_BINDING", class_name: "TEST_DO_CLASS" },
+							{
+								name: "TEST_DO_BINDING",
+								class_name: "TEST_DO_CLASS",
+								script_name: "TEST_DO_SCRIPT",
+							},
 						],
 					},
 					kv_namespaces: [{ binding: "TEST_KV_BINDING", id: "1" }],
@@ -268,6 +272,56 @@ describe("validatePagesConfig()", () => {
 		`);
 		});
 	});
+
+	describe("DO bindings validation", () => {
+		it("should pass if all Durable Objects bindings specify 'script_name'", () => {
+			const config = generateConfigurationWithDefaults();
+			config.pages_build_output_dir = "./public";
+			config.name = "pages-project";
+			config.durable_objects.bindings = [
+				{
+					name: "foo-DO",
+					class_name: "foo-class",
+					script_name: "foo-script",
+				},
+				{
+					name: "bar-DO",
+					class_name: "bar-class",
+					script_name: "bar-script",
+				},
+			];
+
+			const diagnostics = validatePagesConfig(config, [], "pages-project");
+			expect(diagnostics.hasWarnings()).toBeFalsy();
+			expect(diagnostics.hasErrors()).toBeFalsy();
+		});
+
+		it("should fail if any of the Durable Object bindings does not specify 'script_name'", () => {
+			const config = generateConfigurationWithDefaults();
+			config.pages_build_output_dir = "./public";
+			config.name = "pages-project";
+			config.durable_objects.bindings = [
+				{
+					name: "foo-DO",
+					class_name: "foo-class",
+					script_name: "foo-script",
+				},
+				{
+					name: "bar-DO",
+					class_name: "bar-class",
+				},
+			];
+
+			const diagnostics = validatePagesConfig(config, [], "pages-project");
+			expect(diagnostics.hasWarnings()).toBeFalsy();
+			expect(diagnostics.hasErrors()).toBeTruthy();
+			expect(diagnostics.renderErrors()).toMatchInlineSnapshot(`
+			"Running configuration file validation for Pages:
+			  - Durable Objects bindings should specify a \\"script_name\\".
+			    Pages requires Durable Object bindings to specify the name of the Worker where the Durable Object is defined."
+		`);
+		});
+	});
 });
 
 function generateConfigurationWithDefaults() {

packages/wrangler/src/config/validation-pages.ts

@@ -10,6 +10,7 @@
 import { FatalError } from "../errors";
 import { defaultWranglerConfig } from "./config";
 import { Diagnostics } from "./diagnostics";
+import { isRequiredProperty } from "./validation-helpers";
 import type { Config } from "./config";
 
 const supportedPagesConfigFields = [
@@ -56,6 +57,7 @@ export function validatePagesConfig(
 	validateProjectName(projectName, diagnostics);
 	validatePagesEnvironmentNames(envNames, diagnostics);
 	validateUnsupportedFields(config, diagnostics);
+	validateDurableObjectBinding(config, diagnostics);
 
 	return diagnostics;
 }
@@ -159,3 +161,26 @@ function validateUnsupportedFields(config: Config, diagnostics: Diagnostics) {
 		});
 	}
 }
+
+/**
+ * Validate the "script_name" field is specified for [[durable_objects.bindings]]
+ *
+ * This is necessary because Pages cannot define/deploy a DO itself today,
+ * and so this needs to be done with a Worker.
+ */
+function validateDurableObjectBinding(
+	config: Config,
+	diagnostics: Diagnostics
+) {
+	if (config.durable_objects.bindings.length > 0) {
+		const invalidBindings = config.durable_objects.bindings.filter(
+			(binding) => !isRequiredProperty(binding, "script_name", "string")
+		);
+		if (invalidBindings.length > 0) {
+			diagnostics.errors.push(
+				`Durable Objects bindings should specify a "script_name".\n` +
+					`Pages requires Durable Object bindings to specify the name of the Worker where the Durable Object is defined.`
+			);
+		}
+	}
+}