fs: support util.promisify for fs.read/fs.write

PR-URL: https://github.com/nodejs/node/pull/12442
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: William Kapke <william.kapke@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/test/parallel/test-fs-promisified.js b/test/parallel/test-fs-promisified.js
new file mode 100644
index 0000000000..12bd5d6fa1
--- /dev/null
+++ b/test/parallel/test-fs-promisified.js
@@ -0,0 +1,31 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const fs = require('fs');
+const path = require('path');
+const { promisify } = require('util');
+
+common.crashOnUnhandledRejection();
+
+const read = promisify(fs.read);
+const write = promisify(fs.write);
+
+{
+  const fd = fs.openSync(__filename, 'r');
+  read(fd, Buffer.alloc(1024), 0, 1024, null).then(common.mustCall((obj) => {
+    assert.strictEqual(typeof obj.bytesRead, 'number');
+    assert(obj.buffer instanceof Buffer);
+    fs.closeSync(fd);
+  }));
+}
+
+common.refreshTmpDir();
+{
+  const filename = path.join(common.tmpDir, 'write-promise.txt');
+  const fd = fs.openSync(filename, 'w');
+  write(fd, Buffer.from('foobar')).then(common.mustCall((obj) => {
+    assert.strictEqual(typeof obj.bytesWritten, 'number');
+    assert.strictEqual(obj.buffer.toString(), 'foobar');
+    fs.closeSync(fd);
+  }));
+}