fix: add a warning if dev is defaulting to the latest compatibility…

…-date

Fixes cloudflare#741

.changeset/bright-numbers-develop.md

@@ -0,0 +1,7 @@
+---
+"wrangler": patch
+---
+
+fix: add a warning if `dev` is defaulting to the latest compatibility-date
+
+Fixes https://github.com/cloudflare/wrangler2/issues/741

packages/wrangler/src/__tests__/dev.test.tsx

@@ -20,6 +20,53 @@ describe("wrangler dev", () => {
     unsetAllMocks();
   });
 
+  describe("compatibility-date", () => {
+    it("should not warn if there is no wrangler.toml and no compatibility-date specified", async () => {
+      fs.writeFileSync("index.js", `export default {};`);
+      await runWrangler("dev index.js");
+      expect(std.out).toMatchInlineSnapshot(`""`);
+      expect(std.warn).toMatchInlineSnapshot(`""`);
+      expect(std.err).toMatchInlineSnapshot(`""`);
+    });
+
+    it("should warn if there is a wrangler.toml but no compatibility-date", async () => {
+      writeWranglerToml({
+        main: "index.js",
+        compatibility_date: undefined,
+      });
+      fs.writeFileSync("index.js", `export default {};`);
+      await runWrangler("dev");
+      const currentDate = new Date().toISOString().substring(0, 10);
+      expect(std.out).toMatchInlineSnapshot(`""`);
+      expect(std.warn.replaceAll(currentDate, "<current-date>"))
+        .toMatchInlineSnapshot(`
+        "No compatibility_date was specified. Using today's date: <current-date>.
+        Add one to your wrangler.toml file:
+        \`\`\`
+        compatibility_date = \\"<current-date>\\"
+        \`\`\`
+        or pass it in your terminal:
+        \`\`\`
+        --compatibility_date=<current-date>
+        \`\`\`
+        See https://developers.cloudflare.com/workers/platform/compatibility-dates for more information."
+      `);
+      expect(std.err).toMatchInlineSnapshot(`""`);
+    });
+
+    it("should not warn if there is a wrangler.toml but compatibility-date is specified at the command line", async () => {
+      writeWranglerToml({
+        main: "index.js",
+        compatibility_date: undefined,
+      });
+      fs.writeFileSync("index.js", `export default {};`);
+      await runWrangler("dev --compatibility-date=2020-01-01");
+      expect(std.out).toMatchInlineSnapshot(`""`);
+      expect(std.warn).toMatchInlineSnapshot(`""`);
+      expect(std.err).toMatchInlineSnapshot(`""`);
+    });
+  });
+
   describe("entry-points", () => {
     it("should error if there is no entry-point specified", async () => {
       writeWranglerToml();

packages/wrangler/src/dev/dev.tsx

@@ -40,7 +40,7 @@ export type DevProps = {
   crons: Config["triggers"]["crons"];
   public: undefined | string;
   assetPaths: undefined | AssetPaths;
-  compatibilityDate: undefined | string;
+  compatibilityDate: string;
   compatibilityFlags: undefined | string[];
   usageModel: undefined | "bundled" | "unbound";
   build: {

packages/wrangler/src/dev/local.tsx

@@ -17,7 +17,7 @@ interface LocalProps {
   name: undefined | string;
   bundle: EsbuildBundle | undefined;
   format: CfScriptFormat | undefined;
-  compatibilityDate: string | undefined;
+  compatibilityDate: string;
   compatibilityFlags: undefined | string[];
   bindings: CfWorkerInit["bindings"];
   assetPaths: undefined | AssetPaths;

packages/wrangler/src/dev/remote.tsx

@@ -24,7 +24,7 @@ export function Remote(props: {
   accountId: undefined | string;
   apiToken: undefined | string;
   bindings: CfWorkerInit["bindings"];
-  compatibilityDate: string | undefined;
+  compatibilityDate: string;
   compatibilityFlags: undefined | string[];
   usageModel: undefined | "bundled" | "unbound";
   env: string | undefined;

packages/wrangler/src/index.tsx

@@ -883,11 +883,10 @@ export async function main(argv: string[]): Promise<void> {
             args["inspector-port"] ?? (await getPort({ port: 9229 }))
           }
           public={args["experimental-public"]}
-          compatibilityDate={
-            args["compatibility-date"] ||
-            config.compatibility_date ||
-            new Date().toISOString().substring(0, 10)
-          }
+          compatibilityDate={getDevCompatibilityDate(
+            config,
+            args["compatibility-date"]
+          )}
           compatibilityFlags={
             (args["compatibility-flags"] as string[]) ||
             config.compatibility_flags
@@ -1268,10 +1267,7 @@ export async function main(argv: string[]): Promise<void> {
           port={config.dev?.port}
           ip={config.dev.ip}
           public={undefined}
-          compatibilityDate={
-            config.compatibility_date ||
-            new Date().toISOString().substring(0, 10)
-          }
+          compatibilityDate={getDevCompatibilityDate(config)}
           compatibilityFlags={
             (args["compatibility-flags"] as string[]) ||
             config.compatibility_flags
@@ -2390,3 +2386,25 @@ export async function main(argv: string[]): Promise<void> {
     throw e;
   }
 }
+
+function getDevCompatibilityDate(
+  config: Config,
+  compatibilityDate = config.compatibility_date
+) {
+  const currentDate = new Date().toISOString().substring(0, 10);
+  if (config.configPath !== undefined && compatibilityDate === undefined) {
+    console.warn(
+      `No compatibility_date was specified. Using today's date: ${currentDate}.\n` +
+        "Add one to your wrangler.toml file:\n" +
+        "```\n" +
+        `compatibility_date = "${currentDate}"\n` +
+        "```\n" +
+        "or pass it in your terminal:\n" +
+        "```\n" +
+        `--compatibility_date=${currentDate}\n` +
+        "```\n" +
+        "See https://developers.cloudflare.com/workers/platform/compatibility-dates for more information."
+    );
+  }
+  return compatibilityDate ?? currentDate;
+}