docs: for int32LE helper

Author: nbbeeken

test/node/tools/utils.js

@@ -128,13 +128,33 @@ const bufferFromHexArray = array => {
 
 exports.bufferFromHexArray = bufferFromHexArray;
 
-function int32ToHex(int32) {
+/**
+ * A companion helper to bufferFromHexArray to help with constructing bson bytes manually.
+ * When creating a BSON Binary you need a leading little endian int32 followed by a sequence of bytes
+ * of that length.
+ *
+ * @example
+ * ```js
+ * const binAsHex = '000000';
+ * const serializedUUID = bufferFromHexArray([
+ *   '05', // binData type
+ *   '6100', // 'a' & null
+ *   int32ToHex(binAsHex.length / 2), // binary starts with int32 length
+ *   '7F', // user subtype
+ *   binAsHex // uuid bytes
+ * ]);
+ * ```
+ *
+ * @param {number | Int32} int32 -
+ * @returns
+ */
+function int32LEToHex(int32) {
   const buf = Buffer.alloc(4);
-  buf.writeInt32LE(int32, 0);
+  buf.writeInt32LE(+int32, 0);
   return buf.toString('hex');
 }
 
-exports.int32ToHex = int32ToHex;
+exports.int32LEToHex = int32LEToHex;
 
 /**
  * A helper to calculate the byte size of a string (including null)

test/node/uuid.test.ts

@@ -5,7 +5,7 @@ import { BSON, BSONError } from '../register-bson';
 const BSON_DATA_BINARY = BSON.BSONType.binData;
 import { BSON_BINARY_SUBTYPE_UUID_NEW } from '../../src/constants';
 import { expect } from 'chai';
-import { bufferFromHexArray, int32ToHex } from './tools/utils';
+import { bufferFromHexArray, int32LEToHex } from './tools/utils';
 
 // Test values
 const UPPERCASE_DASH_SEPARATED_UUID_STRING = 'AAAAAAAA-AAAA-4AAA-AAAA-AAAAAAAAAAAA';
@@ -158,7 +158,7 @@ describe('UUID', () => {
         const serializedUUID = bufferFromHexArray([
           '05', // binData type
           '6100', // 'a' & null
-          int32ToHex(nullUUID.length / 2), // binary starts with int32 length
+          int32LEToHex(nullUUID.length / 2), // binary starts with int32 length
           '04', // uuid subtype
           nullUUID // uuid bytes
         ]);