fix(wrangler): Add more helpful error messages when validating compatibility date (#7002)

* Add more helpful error messages when validating compatibility date

* PR feedback

---------

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

Author: GregBrimble

.changeset/fifty-dots-end.md

@@ -0,0 +1,5 @@
+---
+"wrangler": patch
+---
+
+fix: More helpful error messages when validating compatibility date

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

@@ -283,6 +283,106 @@ describe("normalizeAndValidateConfig()", () => {
 		`);
 		});
 
+		describe("compatibility_date", () => {
+			it("should allow valid values", () => {
+				const expectedConfig: RawConfig = {
+					compatibility_date: "2024-10-01",
+				};
+
+				const { config, diagnostics } = normalizeAndValidateConfig(
+					expectedConfig,
+					undefined,
+					{ env: undefined }
+				);
+
+				expect(config).toEqual(expect.objectContaining(expectedConfig));
+				expect(diagnostics.hasWarnings()).toBe(false);
+				expect(diagnostics.hasErrors()).toBe(false);
+			});
+
+			it("should error for en-dashes", () => {
+				const expectedConfig: RawConfig = {
+					compatibility_date: "2024–10–01", // en-dash
+				};
+
+				const result = normalizeAndValidateConfig(expectedConfig, undefined, {
+					env: undefined,
+				});
+
+				expect(result.config).toEqual(expect.objectContaining(expectedConfig));
+				expect(result.diagnostics.hasWarnings()).toBe(false);
+				expect(result.diagnostics.hasErrors()).toBe(true);
+
+				expect(normalizeString(result.diagnostics.renderErrors()))
+					.toMatchInlineSnapshot(`
+						"Processing wrangler configuration:
+						  - \\"compatibility_date\\" field should use ISO-8601 accepted hyphens (-) rather than en-dashes (–) or em-dashes (—)."
+					`);
+			});
+
+			it("should error for em-dashes", () => {
+				const expectedConfig = {
+					compatibility_date: "2024—10—01", // em-dash
+				};
+
+				const result = normalizeAndValidateConfig(expectedConfig, undefined, {
+					env: undefined,
+				});
+
+				expect(result.config).toEqual(expect.objectContaining(expectedConfig));
+				expect(result.diagnostics.hasWarnings()).toBe(false);
+				expect(result.diagnostics.hasErrors()).toBe(true);
+
+				expect(normalizeString(result.diagnostics.renderErrors()))
+					.toMatchInlineSnapshot(`
+						"Processing wrangler configuration:
+						  - \\"compatibility_date\\" field should use ISO-8601 accepted hyphens (-) rather than en-dashes (–) or em-dashes (—)."
+					`);
+			});
+
+			it("should error for invalid date values", () => {
+				const expectedConfig: RawConfig = {
+					compatibility_date: "abc",
+				};
+
+				const { config, diagnostics } = normalizeAndValidateConfig(
+					expectedConfig,
+					undefined,
+					{ env: undefined }
+				);
+
+				expect(config).toEqual(expect.objectContaining(expectedConfig));
+				expect(diagnostics.hasErrors()).toBe(true);
+
+				expect(normalizeString(diagnostics.renderErrors()))
+					.toMatchInlineSnapshot(`
+					"Processing wrangler configuration:
+					  - \\"compatibility_date\\" field should be a valid ISO-8601 date (YYYY-MM-DD), but got \\"abc\\"."
+				`);
+			});
+
+			it("should error for dates that are both invalid and include en/em dashes", () => {
+				const expectedConfig = {
+					compatibility_date: "2024—100—01", // invalid date + em-dash
+				};
+
+				const result = normalizeAndValidateConfig(expectedConfig, undefined, {
+					env: undefined,
+				});
+
+				expect(result.config).toEqual(expect.objectContaining(expectedConfig));
+				expect(result.diagnostics.hasWarnings()).toBe(false);
+				expect(result.diagnostics.hasErrors()).toBe(true);
+
+				expect(normalizeString(result.diagnostics.renderErrors()))
+					.toMatchInlineSnapshot(`
+						"Processing wrangler configuration:
+						  - \\"compatibility_date\\" field should use ISO-8601 accepted hyphens (-) rather than en-dashes (–) or em-dashes (—).
+						  - \\"compatibility_date\\" field should be a valid ISO-8601 date (YYYY-MM-DD), but got \\"2024—100—01\\"."
+					`);
+			});
+		});
+
 		describe("[site]", () => {
 			it("should override `site` config defaults with provided values", () => {
 				const expectedConfig: RawConfig = {

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

@@ -250,6 +250,47 @@ export const isValidName: ValidatorFn = (diagnostics, field, value) => {
 	}
 };
 
+/**
+ * Validate that the field is a valid ISO-8601 date time string
+ * see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date#date_time_string_format
+ * or https://tc39.es/ecma262/multipage/numbers-and-dates.html#sec-date-time-string-format
+ */
+export const isValidDateTimeStringFormat = (
+	diagnostics: Diagnostics,
+	field: string,
+	value: string
+): boolean => {
+	let isValid = true;
+
+	// en/em dashes are not valid characters in the JS date time string format.
+	// While they would be caught by the `isNaN(data.getTime())` check below,
+	// we want to single these use cases out, and throw a more specific error
+	if (
+		value.includes("–") || // en-dash
+		value.includes("—") // em-dash
+	) {
+		diagnostics.errors.push(
+			`"${field}" field should use ISO-8601 accepted hyphens (-) rather than en-dashes (–) or em-dashes (—).`
+		);
+		isValid = false;
+	}
+
+	// en/em dashes were already handled above. Let's replace them with hyphens,
+	// which is a valid date time string format character, and evaluate the
+	// resulting date time string further. This ensures we validate for hyphens
+	// only once!
+	const data = new Date(value.replaceAll(/–|—/g, "-"));
+
+	if (isNaN(data.getTime())) {
+		diagnostics.errors.push(
+			`"${field}" field should be a valid ISO-8601 date (YYYY-MM-DD), but got ${JSON.stringify(value)}.`
+		);
+		isValid = false;
+	}
+
+	return isValid;
+};
+
 /**
  * Validate that the field is an array of strings.
  */

packages/wrangler/src/config/validation.ts

@@ -22,6 +22,7 @@ import {
 	isRequiredProperty,
 	isString,
 	isStringArray,
+	isValidDateTimeStringFormat,
 	isValidName,
 	notInheritable,
 	validateAdditionalProperties,
@@ -1173,7 +1174,7 @@ function normalizeAndValidateEnvironment(
 			topLevelEnv,
 			rawEnv,
 			"compatibility_date",
-			isString,
+			validateCompatibilityDate,
 			undefined
 		),
 		compatibility_flags: inheritable(
@@ -3216,6 +3217,21 @@ const validateConsumer: ValidatorFn = (diagnostics, field, value, _config) => {
 	return isValid;
 };
 
+const validateCompatibilityDate: ValidatorFn = (diagnostics, field, value) => {
+	if (value === undefined) {
+		return true;
+	}
+
+	if (typeof value !== "string") {
+		diagnostics.errors.push(
+			`Expected "${field}" to be of type string but got ${JSON.stringify(value)}.`
+		);
+		return false;
+	}
+
+	return isValidDateTimeStringFormat(diagnostics, field, value);
+};
+
 const validatePipelineBinding: ValidatorFn = (diagnostics, field, value) => {
 	if (typeof value !== "object" || value === null) {
 		diagnostics.errors.push(