test(nodekey): add test suite for node key

This creates a unit test suite for the node key module. Currently the
only test verifies that it will generate a valid node key.

test/unit/NodeKey.spec.ts

@@ -0,0 +1,13 @@
+import { expect } from 'chai';
+import chaiAsPromised = require('chai-as-promised');
+import NodeKey from '../../lib/nodekey/NodeKey';
+import secp256k1 from 'secp256k1';
+
+describe('NodeKey', () => {
+  it('should generate a valid node key', async () => {
+    const nodeKey = await NodeKey['generate']();
+    expect(nodeKey.nodePubKey).to.have.length(66);
+    expect(secp256k1.privateKeyVerify(nodeKey['privKey'])).to.be.true;
+    expect(secp256k1.publicKeyVerify(Buffer.from(nodeKey.nodePubKey, 'hex'))).to.be.true;
+  });
+});