For Issue #27, rewrite most tests to use mocha/chai via npm run test

tests/io-bytebuffer.spec.js

@@ -0,0 +1,54 @@
+/*
+ * archive-test.js
+ *
+ * Licensed under the MIT License
+ *
+ * Copyright(c) 2021 Google Inc.
+ */
+
+import { ByteBuffer } from '../io/bytebuffer.js';
+import { ByteStream } from '../io/bytestream.js';
+import 'mocha';
+import { expect } from 'chai';
+
+// TODO: Only test ByteBuffer here.
+describe('bitjs.io.ByteBufferBitStream', () => {
+  let buffer;
+
+  beforeEach(() => {
+    buffer = new ByteBuffer(4);
+  });
+
+  it('Write_SingleByte', () => {
+    buffer.writeNumber(192, 1);
+    expect(buffer.ptr).equals(1);
+  });
+
+  it('Write_SingleByteNegativeNumber', () => {
+    buffer.writeSignedNumber(-120, 1);
+    expect(buffer.ptr).equals(1);
+  });
+
+  it('Write_MultiByteNumber', () => {
+    buffer.writeNumber(1234, 4);
+    const stream = new ByteStream(buffer.data.buffer);
+    expect(buffer.ptr).equals(4);
+  });
+
+  it('Write_MultiByteNegativeNumber', () => {
+    buffer.writeSignedNumber(-1234, 4);
+    expect(buffer.ptr).equals(4);
+  });
+
+  it('WriteOverflowUnsigned', () => {
+    expect(() => buffer.writeNumber(256, 1)).throws();
+  });
+
+  it('WriteOverflowSignedPositive', () => {
+    expect(() => buffer.writeSignedNumber(128, 1)).throws();
+  });
+
+  it('WriteOverflowSignedNegative', () => {
+    expect(() => buffer.writeSignedNumber(-129, 1)).throws();
+  });
+});