feat add BigNumber tests

test/unit/BigNumber.js

@@ -0,0 +1,48 @@
+'use strict';
+
+/* eslint-env node, mocha */
+
+const { assert } = require('chai');
+const { jsbn: { BigInteger } } = require('node-forge');
+
+const BigNumber = require('../../lib/crypto/BigNumber');
+
+const types = [
+	{ name: 'BigNumber', value: new BigNumber(11) },
+	{ name: 'BigInteger', value: new BigInteger('11') },
+	{ name: 'string with default radix', value: '11' },
+	{ name: 'string with radix 16', value: '0b', radix: 16 },
+	{ name: 'Buffer', value: Buffer.from('0b', 'hex') },
+	{ name: 'Array', value: [11] },
+];
+
+describe('BigNumber', () => {
+	describe('creating an instance', () => {
+		it('should throw with no value given', () => assert.throws(() => new BigNumber()));
+		it('should throw wrong value type', () => assert.throws(() => new BigNumber({})));
+
+		for (const { name, value, radix } of types) {
+			let instance;
+			describe(`out of ${name}`, () => {
+				it('create instance', () => assert.doesNotThrow(() => {
+					instance = new BigNumber(value, radix);
+				}));
+				it('toString with radix 10', () => assert.equal(instance.toString(), '11'));
+				it('toString with radix 16', () => assert.equal(instance.toString(16), '0b'));
+				it('toBuffer', () => assert.equal(instance.toBuffer().toString('hex'), '0b'));
+				it('toBEBuffer without length', () => assert.equal(instance.toBEBuffer().toString('hex'), '0b'));
+				it('toBEBuffer with length', () => assert.equal(instance.toBEBuffer(4).toString('hex'), '0000000b'));
+			});
+		}
+	});
+	describe('exports', () => {
+		it('toBEBuffer with too short length should throw', () => assert.throw(() => new BigNumber(837462187362).toBEBuffer(1)));
+	});
+	describe('operators', () => {
+		const num = new BigNumber(1);
+		it('and', () => assert.equal(num.and(1), 1));
+		it('mul', () => assert.equal(num.mul(2), 2));
+		it('mod', () => assert.equal(num.mod(1), 0));
+		it('shrn', () => assert.equal(num.shrn(1), 0));
+	});
+});