diff --git a/eng/pipelines/ci.yml b/eng/pipelines/ci.yml
index 7be82bebfb6..cdddcc923c0 100644
--- a/eng/pipelines/ci.yml
+++ b/eng/pipelines/ci.yml
@@ -74,10 +74,8 @@ jobs:
       - script: |
           inv regenerate
         displayName: 'Regenerate Code'
-      - script: |
-          git add -A  # 'add' first so 'diff' includes untracked files
-          git diff --staged -w
-        displayName: 'Diff regeneration'
+      - script: node ./eng/scripts/check-for-changed-files.js
+        displayName: Fail on regeneration diff
       - task: UsePythonVersion@0
         displayName: 'Use Python $(PythonVersion)'
         inputs:
diff --git a/eng/scripts/check-for-changed-files.js b/eng/scripts/check-for-changed-files.js
new file mode 100644
index 00000000000..3fd1827da29
--- /dev/null
+++ b/eng/scripts/check-for-changed-files.js
@@ -0,0 +1,23 @@
+// @ts-check
+
+const { run } = require("./helpers.js");
+
+const proc = run("git", ["status", "--porcelain"], {
+  encoding: "utf-8",
+  stdio: [null, "pipe", "pipe"],
+});
+
+if (proc.stdout) {
+  console.log(proc.stdout);
+}
+
+if (proc.stderr) {
+  console.error(proc.stderr);
+}
+
+if (proc.stdout || proc.stderr) {
+  console.error(
+    `ERROR: There are diffs in regeneration. Please run 'inv regenerate' and re-run. You may also have to remove 'node_modules' and re-run 'npm install' to get the latest testserver.`,
+  );
+  process.exit(1);
+}
\ No newline at end of file
diff --git a/eng/scripts/helpers.js b/eng/scripts/helpers.js
new file mode 100644
index 00000000000..aac104cb2bd
--- /dev/null
+++ b/eng/scripts/helpers.js
@@ -0,0 +1,83 @@
+// @ts-check
+const { spawn, spawnSync } = require("child_process");
+const { resolve } = require("path");
+
+const repoRoot = resolve(__dirname, "../..");
+const prettier = resolve(
+  repoRoot,
+  "packages/extensions/core/node_modules/.bin/prettier"
+);
+const tsc = resolve(repoRoot, "packages/extensions/core/node_modules/.bin/tsc");
+
+const isCmdOnWindows = ["rush", "npm", "code", "code-insiders", tsc, prettier];
+
+function run(command, args, options) {
+  console.log();
+  console.log(`> ${command} ${args.join(" ")}`);
+
+  options = {
+    stdio: "inherit",
+    sync: true,
+    throwOnNonZeroExit: true,
+    ...options,
+  };
+
+  if (process.platform === "win32" && isCmdOnWindows.includes(command)) {
+    command += ".cmd";
+  }
+
+  const proc = (options.sync ? spawnSync : spawn)(command, args, options);
+  if (proc.error) {
+    if (options.ignoreCommandNotFound && proc.error.code === "ENOENT") {
+      console.log(`Skipped: Command \`${command}\` not found.`);
+    } else {
+      throw proc.error;
+    }
+  } else if (
+    options.throwOnNonZeroExit &&
+    proc.status !== undefined &&
+    proc.status !== 0
+  ) {
+    throw new CommandFailedError(
+      `Command \`${command} ${args.join(" ")}\` failed with exit code ${
+        proc.status
+      }`,
+      proc
+    );
+  }
+
+  return proc;
+}
+
+class CommandFailedError extends Error {
+  constructor(msg, proc) {
+    super(msg);
+    this.proc = proc;
+  }
+}
+
+function runPrettier(...args) {
+  run(
+    prettier,
+    [
+      ...args,
+      "--config",
+      ".prettierrc.yml",
+      "--ignore-path",
+      ".prettierignore",
+      "**/*.{ts,js,cjs,mjs,json,yml,yaml,cadl,md}",
+    ],
+    {
+      cwd: repoRoot,
+    }
+  );
+}
+
+module.exports = {
+  repoRoot,
+  prettier,
+  tsc,
+  run,
+  runPrettier,
+  CommandFailedError,
+};