Add basic client and token unit tests.

tests/ClientTest.php

@@ -0,0 +1,20 @@
+<?php
+
+use GaryJones\OAuth\Client;
+
+class ClientTest extends PHPUnit_Framework_TestCase
+{
+	public function testKeyAndSecretAreSet()
+    {
+        $client = new Client('foo', 'bar');
+        $this->assertEquals('foo', $client->getKey());
+        $this->assertEquals('bar', $client->getSecret());
+    }
+
+	public function testCallbackUrlIsSet()
+    {
+        $client = new Client('foo', 'bar', 'http://example.com/foobar');
+        $this->assertEquals('http://example.com/foobar', $client->getCallbackUrl());
+    }
+
+}