feat: add error messages for missing build cache (denoland#2551)

Author: marvinhagemeister

deno.json

@@ -15,7 +15,7 @@
     "screenshot": "deno run -A www/utils/screenshot.ts",
     "check:types": "deno check src/**/*.ts src/**/*.tsx tests/**/*.ts tests/**/*.tsx update/**/*.ts plugin-tailwindcss/**/*.ts init/**/*.ts",
     "ok": "deno fmt --check && deno lint && deno task check:types && deno task test",
-    "test:www": "deno test -A tests/www/",
+    "test:www": "deno test -A www/main_test.*",
     "release": "deno run -A tools/release.ts"
   },
   "exclude": ["**/_fresh/*", "**/tmp/*", "*/tests_OLD/**"],

deno.lock

@@ -1,7 +1,7 @@
 import { expect } from "@std/expect";
 import { initProject, InitStep, type MockTTY } from "./init.ts";
 import * as path from "@std/path";
-import { withBrowser } from "../../tests/test_utils.tsx";
+import { getStdOutput, withBrowser } from "../../tests/test_utils.tsx";
 import { waitForText } from "../../tests/test_utils.tsx";
 import { withChildProcessServer } from "../../tests/test_utils.tsx";
 
@@ -194,7 +194,7 @@ Deno.test("init - can start dev server", async () => {
   });
 });
 
-Deno.test("init - can start build project", async () => {
+Deno.test("init - can start built project", async () => {
   await withTmpDir(async (dir) => {
     const mock = mockUserInput({
       [InitStep.ProjectName]: ".",
@@ -227,3 +227,29 @@ Deno.test("init - can start build project", async () => {
     );
   });
 });
+
+Deno.test("init - errors on missing build cache in prod", async () => {
+  await withTmpDir(async (dir) => {
+    const mock = mockUserInput({
+      [InitStep.ProjectName]: ".",
+    });
+    await initProject(dir, [], {}, mock.tty);
+    await expectProjectFile(dir, "main.ts");
+    await expectProjectFile(dir, "dev.ts");
+
+    await patchProject(dir);
+
+    const cp = await new Deno.Command(Deno.execPath(), {
+      args: ["run", "-A", "main.ts"],
+      stdin: "null",
+      stdout: "piped",
+      stderr: "piped",
+      cwd: dir,
+    }).output();
+
+    const { stderr } = getStdOutput(cp);
+    expect(cp.code).toEqual(1);
+
+    expect(stderr).toMatch(/Found 1 islands, but did not/);
+  });
+});

init/src/init_test.ts

@@ -171,7 +171,10 @@ export class App<State> {
     (request: Request, info?: Deno.ServeHandlerInfo) => Promise<Response>
   > {
     if (this.#buildCache === null) {
-      this.#buildCache = await ProdBuildCache.fromSnapshot(this.config);
+      this.#buildCache = await ProdBuildCache.fromSnapshot(
+        this.config,
+        this.#islandRegistry.size,
+      );
     }
 
     if (

src/app.ts

@@ -1,5 +1,5 @@
 import { expect } from "@std/expect";
-import { App, setBuildCache } from "./app.ts";
+import { App, getIslandRegistry, setBuildCache } from "./app.ts";
 import { FakeServer } from "./test_utils.ts";
 import { ProdBuildCache } from "./build_cache.ts";
 
@@ -429,7 +429,7 @@ Deno.test.ignore("FreshApp - finish setup", async () => {
       build: {
         outDir: "foo",
       },
-    }),
+    }, getIslandRegistry(app).size),
   );
 
   const server = new FakeServer(await app.handler());

src/app_test.tsx

@@ -1,6 +1,7 @@
 import * as path from "@std/path";
 import type { ResolvedFreshConfig } from "./config.ts";
-import { setBuildId } from "./runtime/build_id.ts";
+import { DENO_DEPLOYMENT_ID, setBuildId } from "./runtime/build_id.ts";
+import * as colors from "@std/fmt/colors";
 
 export interface FileSnapshot {
   generated: boolean;
@@ -28,7 +29,7 @@ export interface BuildCache {
 }
 
 export class ProdBuildCache implements BuildCache {
-  static async fromSnapshot(config: ResolvedFreshConfig) {
+  static async fromSnapshot(config: ResolvedFreshConfig, islandCount: number) {
     const snapshotPath = path.join(config.build.outDir, "snapshot.json");
 
     const staticFiles = new Map<string, FileSnapshot>();
@@ -53,8 +54,29 @@ export class ProdBuildCache implements BuildCache {
         const pathname = islands[i];
         islandToChunk.set(pathname, snapshot.islands[pathname]);
       }
+
+      if (!DENO_DEPLOYMENT_ID) {
+        // deno-lint-ignore no-console
+        console.log(
+          `Found snapshot at ${colors.cyan(snapshotPath)}`,
+        );
+      }
     } catch (err) {
-      if (!(err instanceof Deno.errors.NotFound)) {
+      if ((err instanceof Deno.errors.NotFound)) {
+        if (islandCount > 0) {
+          throw new Error(
+            `Found ${
+              colors.green(`${islandCount} islands`)
+            }, but did not find build snapshot at:\n${
+              colors.red(snapshotPath)
+            }.\n\nMaybe your forgot to run ${
+              colors.cyan("deno task build")
+            } before starting the production server\nor maybe you wanted to run ${
+              colors.cyan("deno task dev")
+            } to spin up a development server instead?\n`,
+          );
+        }
+      } else {
         throw err;
       }
     }

src/build_cache.ts

@@ -1,4 +1,4 @@
-import { App, setBuildCache } from "../src/app.ts";
+import { App, getIslandRegistry, setBuildCache } from "../src/app.ts";
 import { launch, type Page } from "@astral/astral";
 import * as colors from "@std/fmt/colors";
 import { type Document, DOMParser, HTMLElement } from "linkedom";
@@ -66,7 +66,10 @@ export async function buildProd(app: App<unknown>) {
   app.config.build.outDir = outDir;
   const builder = new Builder({});
   await builder.build(app);
-  const cache = await ProdBuildCache.fromSnapshot(app.config);
+  const cache = await ProdBuildCache.fromSnapshot(
+    app.config,
+    getIslandRegistry(app).size,
+  );
   setBuildCache(app, cache);
 }
 

tests/test_utils.tsx

@@ -4,11 +4,11 @@ import { buildProd, withBrowserApp } from "../tests/test_utils.tsx";
 import { expect } from "@std/expect";
 import { retry } from "@std/async/retry";
 
+await buildProd(app);
 const handler = await app.handler();
 
 Deno.test("CORS should not set on GET /fresh-badge.svg", async () => {
   const req = new Request("http://localhost/fresh-badge.svg");
-  await buildProd(app);
   const resp = await handler(req);
   await resp?.body?.cancel();