1 files changed, 31 insertions, 0 deletions
diff --git a/cli/tests/unit_node/tty_test.ts b/cli/tests/unit_node/tty_test.ts
new file mode 100644
index 000000000..d2bf32efc
--- /dev/null
+++ b/cli/tests/unit_node/tty_test.ts
@@ -0,0 +1,31 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+// deno-lint-ignore-file no-explicit-any
+
+import { assert } from "../../../test_util/std/testing/asserts.ts";
+import { isatty } from "node:tty";
+
+Deno.test("[node/tty isatty] returns true when fd is a tty, false otherwise", () => {
+  assert(Deno.isatty(Deno.stdin.rid) === isatty(Deno.stdin.rid));
+  assert(Deno.isatty(Deno.stdout.rid) === isatty(Deno.stdout.rid));
+  assert(Deno.isatty(Deno.stderr.rid) === isatty(Deno.stderr.rid));
+
+  const file = Deno.openSync("README.md");
+  assert(!isatty(file.rid));
+  Deno.close(file.rid);
+});
+
+Deno.test("[node/tty isatty] returns false for irrelevant values", () => {
+  // invalid numeric fd
+  assert(!isatty(1234567));
+
+  // TODO(kt3k): Enable this test when the below issue resolved
+  // https://github.com/denoland/deno/issues/14398
+  // assert(!isatty(-1));
+
+  // invalid type fd
+  assert(!isatty("abc" as any));
+  assert(!isatty({} as any));
+  assert(!isatty([] as any));
+  assert(!isatty(null as any));
+  assert(!isatty(undefined as any));
+});