update constructor and add test assertions

Author: syz99

src/bson.ts

@@ -112,7 +112,7 @@ export interface Document {
 const MAXSIZE = 1024 * 1024 * 17;
 
 // Current Internal Temporary Serialization Buffer
-let buffer = Buffer.alloc(MAXSIZE);
+let buffer = Buffer.allocUnsafe(MAXSIZE);
 
 /**
  * Sets the size of the internal serialization buffer.

src/decimal128.ts

@@ -1,6 +1,7 @@
 import { Buffer } from 'buffer';
 import { BSONTypeError } from './error';
 import { Long } from './long';
+import { isUint8Array } from './parser/utils';
 
 const PARSE_STRING_REGEXP = /^(\+|-)?(\d+|(\d*\.\d*))?(E|e)?([-+])?(\d+)?$/;
 const PARSE_INF_REGEXP = /^(\+|-)?(Infinity|inf)$/i;
@@ -132,8 +133,14 @@ export class Decimal128 {
 
     if (typeof bytes === 'string') {
       this.bytes = Decimal128.fromString(bytes).bytes;
+    } else if (isUint8Array(bytes)) {
+      if (bytes.byteLength === 16) {
+        this.bytes = bytes;
+      } else {
+        throw new BSONTypeError('Decimal128 must take a Buffer of 16 bytes');
+      }
     } else {
-      this.bytes = bytes;
+      throw new BSONTypeError('Decimal128 must take a Buffer or string');
     }
   }
 

test/node/decimal128_tests.js

@@ -1,5 +1,6 @@
 'use strict';
 
+// const { BSONTypeError } = require('../register-bson');
 const BSON = require('../register-bson');
 const Decimal128 = BSON.Decimal128;
 
@@ -1205,7 +1206,7 @@ describe('Decimal128', function () {
     done();
   });
 
-  it('accepts strings in the constructor', function (done) {
+  it('accepts strings in the constructor', () => {
     expect(new Decimal128('0').toString()).to.equal('0');
     expect(new Decimal128('00').toString()).to.equal('0');
     expect(new Decimal128('0.5').toString()).to.equal('0.5');
@@ -1216,6 +1217,24 @@ describe('Decimal128', function () {
     expect(new Decimal128('0.0011').toString()).to.equal('0.0011');
     expect(new Decimal128('0.00110').toString()).to.equal('0.00110');
     expect(new Decimal128('-1e400').toString()).to.equal('-1E+400');
-    done();
+  });
+
+  it.only('throws appropriate error for invalid constructor arguments', () => {
+    const byteLengthErrMsg = 'Decimal128 must take a Buffer of 16 bytes';
+    const constructorArgErrMsg = 'Decimal128 must take a Buffer or string';
+
+    expect(() => new Decimal128(-0)).to.throw(constructorArgErrMsg);
+    expect(() => new Decimal128(-1)).to.throw(constructorArgErrMsg);
+    expect(() => new Decimal128(10)).to.throw(constructorArgErrMsg);
+    expect(() => new Decimal128(1111111111111111)).to.throw(constructorArgErrMsg);
+
+    expect(() => new Decimal128(new Uint8Array(0))).to.throw(byteLengthErrMsg);
+    expect(() => new Decimal128(Buffer.alloc(0))).to.throw(byteLengthErrMsg);
+    expect(() => new Decimal128(new Uint8Array(3))).to.throw(byteLengthErrMsg);
+    expect(() => new Decimal128(Buffer.alloc(3))).to.throw(byteLengthErrMsg);
+    expect(() => new Decimal128(new Uint8Array(17))).to.throw(byteLengthErrMsg);
+    expect(() => new Decimal128(Buffer.alloc(17))).to.throw(byteLengthErrMsg);
+    new Decimal128(Buffer.alloc(16));
+    new Decimal128(new Uint8Array(16));
   });
 });