chore: improve varint leb128 docs and tests

packages/iso-base/src/leb128.js

@@ -1,3 +1,13 @@
+/**
+ * Unsigned LEB128 encoding and decoding.
+ *
+ * Supports bigints and numbers.
+ *
+ * @see https://en.wikipedia.org/wiki/LEB128
+ *
+ * @module
+ */
+
 export const unsigned = {
   /**
    * Decode a Uint8Array into a number.

packages/iso-base/src/varint.js

@@ -1,6 +1,9 @@
-/* eslint-disable no-fallthrough */
 /**
- * Variable length integer encoding with helpers for tagging Uint8Arrays with multicodec prefixes.
+ * Unsigned variable length integer encoding with helpers for tagging Uint8Arrays with multicodec prefixes.
+ * Same as unsigned leb128 encoding but with js safe integers limitations and multiformats rules.
+ *
+ *
+ * @see https://github.com/multiformats/unsigned-varint
  *
  * @module
  */
@@ -135,7 +138,7 @@ export function encode(value, buf, offset = 0) {
 }
 
 /**
- * Decodes buf from position offset or default 0 and returns the decoded original integer.
+ * Decodes buffer from position offset or default 0 and returns the decoded original integer.
  *
  * @param {Uint8Array} buf
  * @param {number} [offset]

packages/iso-base/test/varint.test.js

@@ -1,4 +1,5 @@
 import assert from 'assert'
+import { hex } from '../src/rfc4648.js'
 import { decode, encode, encodingLength } from '../src/varint.js'
 
 /**
@@ -135,4 +136,32 @@ describe('varint', () => {
       }
     )
   })
+
+  /** @type {Array<[string, number , number]>} */
+  const VECTORS = [
+    ['01', 1, 1],
+    ['7f', 127, 1],
+    ['8001', 128, 2],
+    ['ff01', 255, 2],
+    ['ac02', 300, 2],
+    ['808001', 16384, 3],
+    ['d901', 217, 2],
+    ['e29a01', 19_810, 3],
+    ['e086bd2b', 91_177_824, 4],
+    ['e599c7ed09', 2_645_675_237, 5],
+  ]
+  for (const [b, num, size] of VECTORS) {
+    const bytes = hex.decode(b)
+    it(`${b} decode`, () => {
+      assert.deepStrictEqual(decode(bytes)[0], num)
+    })
+
+    it(`${b} size`, () => {
+      assert.deepStrictEqual(encodingLength(num), size)
+    })
+
+    it(`${b} encode`, () => {
+      assert.deepStrictEqual(encode(num)[0], bytes)
+    })
+  }
 })

packages/iso-base/tsconfig.json

@@ -15,7 +15,8 @@
       "src/utils.js",
       "src/base-x.js",
       "src/varint.js",
-      "src/ec-compression.js"
+      "src/ec-compression.js",
+      "src/leb128.js"
     ],
     "includeVersion": true,
     "excludeExternals": true,