fs: fix errorOnExist behavior for directory copy in fs.cp

lib/internal/fs/cp/cp.js

@@ -300,8 +300,17 @@ async function setDestTimestamps(src, dest) {
   return utimes(dest, updatedSrcStat.atime, updatedSrcStat.mtime);
 }
 
-function onDir(srcStat, destStat, src, dest, opts) {
+async function onDir(srcStat, destStat, src, dest, opts) {
   if (!destStat) return mkDirAndCopy(srcStat.mode, src, dest, opts);
+  if (opts.errorOnExist && !opts.force) {
+    throw new ERR_FS_CP_EEXIST({
+      message: `${dest} already exists`,
+      path: dest,
+      syscall: 'cp',
+      errno: EEXIST,
+      code: 'EEXIST',
+    });
+  }
   return copyDir(src, dest, opts);
 }
 

test/parallel/test-fs-cp-async-dir-exists-error-on-exist.mjs

@@ -0,0 +1,30 @@
+// This tests that cp() returns error if errorOnExist is true, force is false,
+// and the destination directory already exists (even if contents don't conflict).
+
+import { mustCall } from '../common/index.mjs';
+import { nextdir } from '../common/fs.js';
+import assert from 'node:assert';
+import { cp, mkdirSync, writeFileSync } from 'node:fs';
+import tmpdir from '../common/tmpdir.js';
+
+tmpdir.refresh();
+
+const src = nextdir();
+const dest = nextdir();
+
+// Create source directory with a file
+mkdirSync(src);
+writeFileSync(`${src}/file.txt`, 'test');
+
+// Create destination directory with different file
+mkdirSync(dest);
+writeFileSync(`${dest}/other.txt`, 'existing');
+
+// Should fail because dest directory already exists
+cp(src, dest, {
+  recursive: true,
+  errorOnExist: true,
+  force: false,
+}, mustCall((err) => {
+  assert.strictEqual(err.code, 'ERR_FS_CP_EEXIST');
+}));