Refactor: directory structure (#31)

* config: update version
* refactor: move source codes to lib directory, Close #30
* refactor: move test code

__tests__/index.test.js

@@ -0,0 +1,23 @@
+const wait = require('./wait');
+const process = require('process');
+const cp = require('child_process');
+const path = require('path');
+
+test('throws invalid number', async() => {
+    await expect(wait('foo')).rejects.toThrow('milleseconds not a number');
+});
+
+test('wait 500 ms', async() => {
+    const start = new Date();
+    await wait(500);
+    const end = new Date();
+    var delta = Math.abs(end - start);
+    expect(delta).toBeGreaterThan(450);
+});
+
+// shows how the runner will run a javascript action with env / stdout protocol
+test('test runs', () => {
+    process.env['INPUT_MILLISECONDS'] = 500;
+    const ip = path.join(__dirname, 'index.js');
+    console.log(cp.execSync(`node ${ip}`).toString());
+})