From d48ebcd49dd5ec6074b84884606acb86eda7c75e Mon Sep 17 00:00:00 2001
From: Irakli Gozalishvili <contact@gozala.io>
Date: Wed, 14 Sep 2022 23:58:57 -0700
Subject: [PATCH 1/2] feat: add optional offset param to varint.decode

---
 src/varint.js | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/varint.js b/src/varint.js
index 0fa7b319..d0c71eac 100644
--- a/src/varint.js
+++ b/src/varint.js
@@ -2,10 +2,11 @@ import varint from '../vendor/varint.js'
 
 /**
  * @param {Uint8Array} data
+ * @param {number} [offset=0]
  * @returns {[number, number]}
  */
-export const decode = (data) => {
-  const code = varint.decode(data)
+export const decode = (data, offset = 0) => {
+  const code = varint.decode(data, offset)
   return [code, varint.decode.bytes]
 }
 

From 7196a9e49df6914290a096dd2c5461d1ea1c9ed0 Mon Sep 17 00:00:00 2001
From: Irakli Gozalishvili <contact@gozala.io>
Date: Thu, 15 Sep 2022 00:14:11 -0700
Subject: [PATCH 2/2] create unit test

---
 test/test-varint.js | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 test/test-varint.js

diff --git a/test/test-varint.js b/test/test-varint.js
new file mode 100644
index 00000000..e875e95b
--- /dev/null
+++ b/test/test-varint.js
@@ -0,0 +1,28 @@
+/* globals describe, it */
+
+import { varint } from 'multiformats'
+import chai from 'chai'
+import chaiAsPromised from 'chai-as-promised'
+
+chai.use(chaiAsPromised)
+const { assert } = chai
+
+const UTF8 = new TextEncoder()
+
+describe('varint', () => {
+  it('can decode with offset', () => {
+    const message = UTF8.encode('hello-world')
+    const outerTag = 0x55
+    const innerTag = 0xe3
+    const outerTagSize = varint.encodingLength(outerTag)
+    const innerTagSize = varint.encodingLength(innerTag)
+
+    const bytes = new Uint8Array(message.byteLength + outerTagSize + innerTagSize)
+    varint.encodeTo(outerTag, bytes)
+    varint.encodeTo(innerTag, bytes, outerTagSize)
+    bytes.set(message, outerTagSize + innerTagSize)
+
+    assert.deepStrictEqual(varint.decode(bytes), [outerTag, outerTagSize])
+    assert.deepStrictEqual(varint.decode(bytes, outerTagSize), [innerTag, innerTagSize])
+  })
+})