1 files changed, 51 insertions, 0 deletions
diff --git a/tests/unit_node/_fs/_fs_write_test.ts b/tests/unit_node/_fs/_fs_write_test.ts
new file mode 100644
index 000000000..7e75f321f
--- /dev/null
+++ b/tests/unit_node/_fs/_fs_write_test.ts
@@ -0,0 +1,51 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+import { write, writeSync } from "node:fs";
+import { assertEquals } from "@test_util/std/assert/mod.ts";
+import { Buffer } from "node:buffer";
+
+const decoder = new TextDecoder("utf-8");
+
+Deno.test({
+  name: "Data is written to the file with the correct length",
+  async fn() {
+    const tempFile: string = await Deno.makeTempFile();
+    using file = await Deno.open(tempFile, {
+      create: true,
+      write: true,
+      read: true,
+    });
+    const buffer = Buffer.from("hello world");
+    const bytesWrite = await new Promise((resolve, reject) => {
+      write(file.rid, buffer, 0, 5, (err: unknown, nwritten: number) => {
+        if (err) return reject(err);
+        resolve(nwritten);
+      });
+    });
+
+    const data = await Deno.readFile(tempFile);
+    await Deno.remove(tempFile);
+
+    assertEquals(bytesWrite, 5);
+    assertEquals(decoder.decode(data), "hello");
+  },
+});
+
+Deno.test({
+  name: "Data is written synchronously to the file with the correct length",
+  fn() {
+    const tempFile: string = Deno.makeTempFileSync();
+    using file = Deno.openSync(tempFile, {
+      create: true,
+      write: true,
+      read: true,
+    });
+    const buffer = Buffer.from("hello world");
+    const bytesWrite = writeSync(file.rid, buffer, 0, 5);
+
+    const data = Deno.readFileSync(tempFile);
+    Deno.removeSync(tempFile);
+
+    assertEquals(bytesWrite, 5);
+    assertEquals(decoder.decode(data), "hello");
+  },
+});