1 files changed, 65 insertions, 0 deletions
diff --git a/tests/unit_node/internal/_randomFill_test.ts b/tests/unit_node/internal/_randomFill_test.ts
new file mode 100644
index 000000000..d85569960
--- /dev/null
+++ b/tests/unit_node/internal/_randomFill_test.ts
@@ -0,0 +1,65 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+import { Buffer } from "node:buffer";
+import { randomFill, randomFillSync } from "node:crypto";
+import {
+  assertEquals,
+  assertNotEquals,
+  assertThrows,
+} from "@test_util/std/assert/mod.ts";
+
+const validateNonZero = (buf: Buffer) => {
+  if (!buf.some((ch) => ch > 0)) throw new Error("Error");
+};
+
+const validateZero = (buf: Buffer) => {
+  buf.forEach((val) => assertEquals(val, 0));
+};
+
+Deno.test("[node/crypto.randomFill]", async () => {
+  const { promise, resolve } = Promise.withResolvers<boolean>();
+  const buf = Buffer.alloc(10);
+  const before = buf.toString("hex");
+
+  randomFill(buf, 5, 5, (_err, bufTwo) => {
+    const after = bufTwo?.toString("hex");
+    assertEquals(before.slice(0, 10), after?.slice(0, 10));
+    resolve(true);
+  });
+
+  await promise;
+});
+
+Deno.test("[node/crypto.randomFillSync]", () => {
+  const buf = Buffer.alloc(10);
+  const before = buf.toString("hex");
+
+  const after = randomFillSync(buf, 5, 5);
+
+  assertNotEquals(before, after.toString("hex"));
+});
+
+Deno.test("[node/crypto.randomFillSync] Complete fill, explicit size", () => {
+  const buf = Buffer.alloc(10);
+  randomFillSync(buf, undefined, 10);
+  validateNonZero(buf);
+});
+
+Deno.test("[randomFillSync] Complete fill", () => {
+  const buf = Buffer.alloc(10);
+  randomFillSync(buf);
+  validateNonZero(buf);
+});
+
+Deno.test("[node/crypto.randomFillSync] Fill beginning, explicit offset+size", () => {
+  const buf = Buffer.alloc(10);
+  randomFillSync(buf, 0, 5);
+  validateNonZero(buf);
+
+  const untouched = buf.slice(5);
+  assertEquals(untouched.length, 5);
+  validateZero(untouched);
+});
+
+Deno.test("[node/crypto.randomFillSync] Invalid offst/size", () => {
+  assertThrows(() => randomFillSync(Buffer.alloc(10), 1, 10));
+});