feat(remix-dev): add warning when future.v2_routeConvention is not enabled

.changeset/lazy-dots-sip.md

@@ -0,0 +1,6 @@
+---
+"remix": patch
+"@remix-run/dev": patch
+---
+
+add warning when `future.v2_routeConvention` is not enabled

integration/flat-routes-test.ts

@@ -147,6 +147,53 @@ test.describe("flat routes", () => {
   }
 });
 
+test.describe("warns when v1 routesConvention is used", () => {
+  let buildStdio = new PassThrough();
+  let buildOutput: string;
+
+  let originalConsoleLog = console.log;
+  let originalConsoleWarn = console.warn;
+  let originalConsoleError = console.error;
+
+  test.beforeAll(async () => {
+    console.log = () => {};
+    console.warn = () => {};
+    console.error = () => {};
+    await createFixtureProject({
+      buildStdio,
+      files: {
+        "routes/index.tsx": js`
+          export default function () {
+            return <p>routes/index</p>;
+          }
+        `,
+      },
+    });
+
+    let chunks: Buffer[] = [];
+    buildOutput = await new Promise<string>((resolve, reject) => {
+      buildStdio.on("data", (chunk) => chunks.push(Buffer.from(chunk)));
+      buildStdio.on("error", (err) => reject(err));
+      buildStdio.on("end", () =>
+        resolve(Buffer.concat(chunks).toString("utf8"))
+      );
+    });
+  });
+
+  test.afterAll(() => {
+    console.log = originalConsoleLog;
+    console.warn = originalConsoleWarn;
+    console.error = originalConsoleError;
+  });
+
+  test("warns about conflicting routes", () => {
+    console.log(buildOutput);
+    expect(buildOutput).toContain(
+      `The old route convention has been deprecated in favor of "flat routes". Please enable it via your remix.config https://remix.run/docs/en/main/file-conventions/route-files-v2`
+    );
+  });
+});
+
 test.describe("emits warnings for route conflicts", async () => {
   let buildStdio = new PassThrough();
   let buildOutput: string;

integration/hmr-test.ts

@@ -14,6 +14,7 @@ let fixture = (options: { port: number; appServerPort: number }) => ({
       appServerPort: options.appServerPort,
     },
     unstable_tailwind: true,
+    v2_routeConvention: true,
   },
   files: {
     "package.json": `
@@ -124,7 +125,7 @@ let fixture = (options: { port: number; appServerPort: number }) => ({
           );
         }
       `,
-    "app/routes/index.tsx": `
+    "app/routes/_index.tsx": `
         import { useLoaderData } from "@remix-run/react";
         export default function Index() {
           const t = useLoaderData();
@@ -235,7 +236,7 @@ test("HMR", async ({ page }) => {
     await counter.click();
     await page.waitForSelector(`#root-counter:has-text("inc 1")`);
 
-    let indexPath = path.join(projectDir, "app", "routes", "index.tsx");
+    let indexPath = path.join(projectDir, "app", "routes", "_index.tsx");
     let originalIndex = fs.readFileSync(indexPath, "utf8");
     let counterPath = path.join(projectDir, "app", "components", "counter.tsx");
     let originalCounter = fs.readFileSync(counterPath, "utf8");

packages/remix-dev/__tests__/create-test.ts

@@ -8,6 +8,7 @@ import stripAnsi from "strip-ansi";
 
 import { run } from "../cli/run";
 import { server } from "./msw";
+import { flatRoutesWarning } from "../config";
 
 beforeAll(() => server.listen({ onUnhandledRequest: "error" }));
 afterAll(() => server.close());
@@ -347,7 +348,9 @@ describe("the create command", () => {
       "--no-typescript",
     ]);
     expect(output.trim()).toBe(
-      getOptOutOfInstallMessage() +
+      flatRoutesWarning +
+        "\n\n" +
+        getOptOutOfInstallMessage() +
         "\n\n" +
         getSuccessMessage(path.join("<TEMP_DIR>", "template-to-js"))
     );

packages/remix-dev/config.ts

@@ -560,9 +560,14 @@ export async function readConfig(
     root: { path: "", id: "root", file: rootRouteFile },
   };
 
-  let routesConvention = appConfig.future?.v2_routeConvention
-    ? flatRoutes
-    : defineConventionalRoutes;
+  let routesConvention: typeof flatRoutes;
+
+  if (appConfig.future?.v2_routeConvention) {
+    routesConvention = flatRoutes;
+  } else {
+    warnOnce(flatRoutesWarning, "v2_routeConvention");
+    routesConvention = defineConventionalRoutes;
+  }
 
   if (fse.existsSync(path.resolve(appDirectory, "routes"))) {
     let conventionalRoutes = routesConvention(
@@ -727,3 +732,4 @@ let listFormat = new Intl.ListFormat("en", {
 });
 
 export let serverBuildTargetWarning = `The "serverBuildTarget" config option is deprecated. Use a combination of "publicPath", "serverBuildPath", "serverConditions", "serverDependenciesToBundle", "serverMainFields", "serverMinify", "serverModuleFormat" and/or "serverPlatform" instead.`;
+export let flatRoutesWarning = `The old route convention has been deprecated in favor of "flat routes". Please enable it via your remix.config https://remix.run/docs/en/main/file-conventions/route-files-v2`;