diff --git a/package.json b/package.json
index 378673e..d9c7f80 100644
--- a/package.json
+++ b/package.json
@@ -30,6 +30,7 @@
     "globals": "^15.3.0",
     "prettier": "^3.2.5",
     "release-plan": "^0.9.0",
+    "strip-ansi": "^7.1.0",
     "tmp-promise": "^3.0.3",
     "vitest": "^1.6.0"
   },
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 84f3238..98e5c64 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -42,6 +42,9 @@ importers:
       release-plan:
         specifier: ^0.9.0
         version: 0.9.0(encoding@0.1.13)
+      strip-ansi:
+        specifier: ^7.1.0
+        version: 7.1.0
       tmp-promise:
         specifier: ^3.0.3
         version: 3.0.3
diff --git a/tests/default.test.mjs b/tests/default.test.mjs
index 30e74fc..cd607c8 100644
--- a/tests/default.test.mjs
+++ b/tests/default.test.mjs
@@ -3,7 +3,8 @@ import { join } from 'path';
 import tmp from 'tmp-promise';
 import { execa } from 'execa';
 import copyWithTemplate from '../lib/copy-with-template';
-import { existsSync } from 'fs';
+import { existsSync, writeFileSync } from 'fs';
+import stripAnsi from 'strip-ansi';
 
 const blueprintPath = join(__dirname, '..');
 const appName = 'fancy-app-in-test';
@@ -35,7 +36,11 @@ describe('basic functionality', function () {
   });
 
   afterAll(async () => {
-    return tmpDir.cleanup();
+    try {
+      await tmpDir.cleanup();
+    } catch {
+      // if it fails to cleaup we don't want to break CI
+    }
   });
 
   it('verify files', async function () {
@@ -79,6 +84,74 @@ describe('basic functionality', function () {
     console.log(result.stdout);
   });
 
+  it('successfully runs tests in dev mode', async function () {
+    await execa({
+      cwd: join(tmpDir.path, appName),
+    })`pnpm install --save-dev testem http-proxy`;
+    let appURL;
+
+    let server;
+
+    try {
+      server = execa('pnpm', ['start'], {
+        cwd: join(tmpDir.path, appName),
+      });
+
+      await new Promise((resolve) => {
+        server.stdout.on('data', (line) => {
+          let result = /Local:\s+(https?:\/\/.*)\//g.exec(
+            stripAnsi(line.toString()),
+          );
+
+          if (result) {
+            appURL = result[1];
+            resolve();
+          }
+        });
+      });
+
+      writeFileSync(
+        join(tmpDir.path, appName, 'testem-dev.js'),
+        `module.exports = {
+  test_page: 'tests/index.html?hidepassed',
+  disable_watching: true,
+  launch_in_ci: ['Chrome'],
+  launch_in_dev: ['Chrome'],
+  browser_start_timeout: 120,
+  browser_args: {
+    Chrome: {
+      ci: [
+        // --no-sandbox is needed when running Chrome inside a container
+        process.env.CI ? '--no-sandbox' : null,
+        '--headless',
+        '--disable-dev-shm-usage',
+        '--disable-software-rasterizer',
+        '--mute-audio',
+        '--remote-debugging-port=0',
+        '--window-size=1440,900',
+      ].filter(Boolean),
+    },
+  },
+  middleware: [
+    require(__dirname + '/testem-proxy.js')('${appURL}')
+  ],
+};
+`,
+      );
+
+      let testResult = await execa(
+        'pnpm',
+        ['testem', '--file', 'testem-dev.js', 'ci'],
+        {
+          cwd: join(tmpDir.path, appName),
+        },
+      );
+      expect(testResult.exitCode).to.eq(0, testResult.output);
+    } finally {
+      server?.kill('SIGINT');
+    }
+  });
+
   it('successfully optimizes deps', function () {
     return execa('pnpm', ['vite', 'optimize', '--force'], {
       cwd: join(tmpDir.path, appName),
diff --git a/tests/fixture/testem-proxy.js b/tests/fixture/testem-proxy.js
new file mode 100644
index 0000000..c8c2b39
--- /dev/null
+++ b/tests/fixture/testem-proxy.js
@@ -0,0 +1,35 @@
+const httpProxy = require('http-proxy');
+
+/*
+  This can be installed as a testem middleware to make testem run against an
+  arbitrary real webserver at targetURL.
+
+  It allows testem to handle the well-known testem-specific paths and proxies
+  everything else, while rewriting the testem-added prefix out of your
+  "/tests/index.html" URL.
+*/
+
+module.exports = function testemProxy(targetURL) {
+  return function testemProxyHandler(app) {
+    const proxy = httpProxy.createProxyServer({
+      changeOrigin: true,
+      ignorePath: true,
+    });
+
+    proxy.on('error', (err, _req, res) => {
+      res && res.status && res.status(500).json(err);
+    });
+
+    app.all('*', (req, res, next) => {
+      let url = req.url;
+      if (url === '/testem.js' || url.startsWith('/testem/')) {
+        return next();
+      }
+      let m = /^(\/\d+)\/tests\/index.html/.exec(url);
+      if (m) {
+        url = url.slice(m[1].length);
+      }
+      proxy.web(req, res, { target: targetURL + url });
+    });
+  };
+}