Fix Bun.serve to respect development flag for sourcemap generation

When development: false is set in Bun.serve, sourcemaps should not be generated or included in the bundled output. Previously, sourcemaps were always generated with config.source_map = .linked regardless of the development mode. This change makes sourcemap generation conditional: - development: false -> config.source_map = .none - development: true -> config.source_map = .linked Added comprehensive tests to verify: - Sourcemaps are not included when development: false - Sourcemaps are included when development: true - Sourcemaps are included when development: { hmr: false } 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
2026-02-17 06:12:08 +00:00 · 2025-11-09 22:04:40 +00:00
5 changed files with 336 additions and 1 deletions
--- a/src/bun.js/api/server/HTMLBundle.zig
+++ b/src/bun.js/api/server/HTMLBundle.zig
@@ -282,11 +282,12 @@ pub const Route = struct {
        if (!is_development) {
            bun.handleOom(config.define.put("process.env.NODE_ENV", "\"production\""));
            config.jsx.development = false;
+            config.source_map = .none;
        } else {
            config.force_node_env = .development;
            config.jsx.development = true;
+            config.source_map = .linked;
        }
-        config.source_map = .linked;

        const completion_task = try bun.BundleV2.createAndScheduleCompletionTask(
            config,
--- a/test/js/bun/http/bun-serve-html-sourcemaps.test.ts
+++ b/test/js/bun/http/bun-serve-html-sourcemaps.test.ts
@@ -0,0 +1,249 @@
+import type { Subprocess } from "bun";
+import { describe, expect, test } from "bun:test";
+import { bunEnv, bunExe, tempDirWithFiles } from "harness";
+import { join } from "path";
+
+describe("Bun.serve sourcemap generation", () => {
+  test("development: false should not include sourcemap comments in JS", async () => {
+    const dir = tempDirWithFiles("html-no-sourcemaps", {
+      "index.html": /*html*/ `
+        <!DOCTYPE html>
+        <html>
+          <head>
+            <title>Production Build</title>
+            <script type="module" src="script.js"></script>
+          </head>
+          <body>
+            <h1>Production</h1>
+          </body>
+        </html>
+      `,
+      "script.js": /*js*/ `
+        console.log("Hello from production");
+        const foo = () => {
+          return "bar";
+        };
+        foo();
+      `,
+    });
+
+    const { subprocess, port, hostname } = await waitForProductionServer(dir, {
+      "/": join(dir, "index.html"),
+    });
+    await using server = subprocess;
+
+    const html = await (await fetch(`http://${hostname}:${port}/`)).text();
+    const jsSrc = html.match(/<script type="module" crossorigin src="([^"]+)"/)?.[1];
+
+    if (!jsSrc) {
+      throw new Error("No script src found in HTML");
+    }
+
+    const response = await fetch(new URL(jsSrc, `http://${hostname}:${port}`));
+    const js = await response.text();
+    const headers = response.headers;
+
+    // Should NOT contain sourceMappingURL comment
+    expect(js).not.toContain("sourceMappingURL");
+
+    // Should NOT have SourceMap header
+    expect(headers.get("SourceMap")).toBeNull();
+  });
+
+  test("development: true should include sourcemap comments in JS", async () => {
+    const dir = tempDirWithFiles("html-with-sourcemaps", {
+      "index.html": /*html*/ `
+        <!DOCTYPE html>
+        <html>
+          <head>
+            <title>Development Build</title>
+            <script type="module" src="script.js"></script>
+          </head>
+          <body>
+            <h1>Development</h1>
+          </body>
+        </html>
+      `,
+      "script.js": /*js*/ `
+        console.log("Hello from development");
+        const foo = () => {
+          return "bar";
+        };
+        foo();
+      `,
+    });
+
+    const { subprocess, port, hostname } = await waitForDevelopmentServer(dir, {
+      "/": join(dir, "index.html"),
+    });
+    await using server = subprocess;
+
+    const html = await (await fetch(`http://${hostname}:${port}/`)).text();
+    const jsSrc = html.match(/<script type="module" crossorigin src="([^"]+)"/)?.[1];
+
+    if (!jsSrc) {
+      throw new Error("No script src found in HTML");
+    }
+
+    const response = await fetch(new URL(jsSrc, `http://${hostname}:${port}`));
+    const js = await response.text();
+    const headers = response.headers;
+
+    // SHOULD contain sourceMappingURL comment
+    expect(js).toContain("sourceMappingURL");
+
+    // SHOULD have SourceMap header
+    expect(headers.get("SourceMap")).toBeTruthy();
+  });
+
+  test("development: { hmr: false } should not include sourcemap comments", async () => {
+    const dir = tempDirWithFiles("html-dev-no-hmr", {
+      "index.html": /*html*/ `
+        <!DOCTYPE html>
+        <html>
+          <head>
+            <title>Development without HMR</title>
+            <script type="module" src="script.js"></script>
+          </head>
+          <body>
+            <h1>Development without HMR</h1>
+          </body>
+        </html>
+      `,
+      "script.js": /*js*/ `
+        console.log("Hello from dev no hmr");
+      `,
+    });
+
+    const { subprocess, port, hostname } = await waitForDevNoHMRServer(dir, {
+      "/": join(dir, "index.html"),
+    });
+    await using server = subprocess;
+
+    const html = await (await fetch(`http://${hostname}:${port}/`)).text();
+    const jsSrc = html.match(/<script type="module" crossorigin src="([^"]+)"/)?.[1];
+
+    if (!jsSrc) {
+      throw new Error("No script src found in HTML");
+    }
+
+    const response = await fetch(new URL(jsSrc, `http://${hostname}:${port}`));
+    const js = await response.text();
+    const headers = response.headers;
+
+    // In development mode (even without HMR), sourcemaps SHOULD be included
+    expect(js).toContain("sourceMappingURL");
+    expect(headers.get("SourceMap")).toBeTruthy();
+  });
+});
+
+async function waitForProductionServer(
+  dir: string,
+  entryPoints: Record<string, string>,
+): Promise<{
+  subprocess: Subprocess;
+  port: number;
+  hostname: string;
+}> {
+  let defer = Promise.withResolvers<{
+    subprocess: Subprocess;
+    port: number;
+    hostname: string;
+  }>();
+
+  const process = Bun.spawn({
+    cmd: [bunExe(), join(import.meta.dir, "fixtures", "serve-production.js")],
+    env: {
+      ...bunEnv,
+      NODE_ENV: undefined,
+    },
+    cwd: dir,
+    stdio: ["inherit", "inherit", "inherit"],
+    ipc(message, subprocess) {
+      subprocess.send({
+        files: entryPoints,
+      });
+      defer.resolve({
+        subprocess,
+        port: message.port,
+        hostname: message.hostname,
+      });
+    },
+  });
+
+  return defer.promise;
+}
+
+async function waitForDevelopmentServer(
+  dir: string,
+  entryPoints: Record<string, string>,
+): Promise<{
+  subprocess: Subprocess;
+  port: number;
+  hostname: string;
+}> {
+  let defer = Promise.withResolvers<{
+    subprocess: Subprocess;
+    port: number;
+    hostname: string;
+  }>();
+
+  const process = Bun.spawn({
+    cmd: [bunExe(), join(import.meta.dir, "fixtures", "serve-development.js")],
+    env: {
+      ...bunEnv,
+      NODE_ENV: undefined,
+    },
+    cwd: dir,
+    stdio: ["inherit", "inherit", "inherit"],
+    ipc(message, subprocess) {
+      subprocess.send({
+        files: entryPoints,
+      });
+      defer.resolve({
+        subprocess,
+        port: message.port,
+        hostname: message.hostname,
+      });
+    },
+  });
+
+  return defer.promise;
+}
+
+async function waitForDevNoHMRServer(
+  dir: string,
+  entryPoints: Record<string, string>,
+): Promise<{
+  subprocess: Subprocess;
+  port: number;
+  hostname: string;
+}> {
+  let defer = Promise.withResolvers<{
+    subprocess: Subprocess;
+    port: number;
+    hostname: string;
+  }>();
+
+  const process = Bun.spawn({
+    cmd: [bunExe(), join(import.meta.dir, "fixtures", "serve-dev-no-hmr.js")],
+    env: {
+      ...bunEnv,
+      NODE_ENV: undefined,
+    },
+    cwd: dir,
+    stdio: ["inherit", "inherit", "inherit"],
+    ipc(message, subprocess) {
+      subprocess.send({
+        files: entryPoints,
+      });
+      defer.resolve({
+        subprocess,
+        port: message.port,
+        hostname: message.hostname,
+      });
+    },
+  });
+
+  return defer.promise;
+}
--- a/test/js/bun/http/fixtures/serve-dev-no-hmr.js
+++ b/test/js/bun/http/fixtures/serve-dev-no-hmr.js
@@ -0,0 +1,31 @@
+let server = Bun.serve({
+  port: 0,
+  development: {
+    hmr: false,
+  },
+  async fetch(req) {
+    return new Response("Hello World", {
+      status: 404,
+    });
+  },
+});
+
+process.on("message", async message => {
+  const files = message.files || {};
+  const routes = {};
+  for (const [key, value] of Object.entries(files)) {
+    routes[key] = (await import(value)).default;
+  }
+
+  server.reload({
+    static: routes,
+    development: {
+      hmr: false,
+    },
+  });
+});
+
+process.send({
+  port: server.port,
+  hostname: server.hostname,
+});
--- a/test/js/bun/http/fixtures/serve-development.js
+++ b/test/js/bun/http/fixtures/serve-development.js
@@ -0,0 +1,27 @@
+let server = Bun.serve({
+  port: 0,
+  development: true,
+  async fetch(req) {
+    return new Response("Hello World", {
+      status: 404,
+    });
+  },
+});
+
+process.on("message", async message => {
+  const files = message.files || {};
+  const routes = {};
+  for (const [key, value] of Object.entries(files)) {
+    routes[key] = (await import(value)).default;
+  }
+
+  server.reload({
+    static: routes,
+    development: true,
+  });
+});
+
+process.send({
+  port: server.port,
+  hostname: server.hostname,
+});
--- a/test/js/bun/http/fixtures/serve-production.js
+++ b/test/js/bun/http/fixtures/serve-production.js
@@ -0,0 +1,27 @@
+let server = Bun.serve({
+  port: 0,
+  development: false,
+  async fetch(req) {
+    return new Response("Hello World", {
+      status: 404,
+    });
+  },
+});
+
+process.on("message", async message => {
+  const files = message.files || {};
+  const routes = {};
+  for (const [key, value] of Object.entries(files)) {
+    routes[key] = (await import(value)).default;
+  }
+
+  server.reload({
+    static: routes,
+    development: false,
+  });
+});
+
+process.send({
+  port: server.port,
+  hostname: server.hostname,
+});