Added some tests and factory impl

tests/spec/BuilderSpec.php

@@ -0,0 +1,38 @@
+<?php
+namespace spec\Madkom\NginxConfigurator;
+
+use Madkom\NginxConfigurator\Builder;
+use Madkom\NginxConfigurator\Config\Server;
+use Madkom\NginxConfigurator\Config\Upstream;
+use PhpSpec\ObjectBehavior;
+use Prophecy\Argument;
+
+/**
+ * Class BuilderSpec
+ * @package spec\Madkom\NginxConfigurator
+ * @author Michał Brzuchalski <m.brzuchalski@madkom.pl>
+ * @mixin Builder
+ */
+class BuilderSpec extends ObjectBehavior
+{
+    function it_is_initializable()
+    {
+        $this->shouldHaveType(Builder::class);
+    }
+
+    function it_can_build_with_Server_node(Server $server)
+    {
+        $server->__toString()->willReturn("server {
+}");
+        $this->append($server);
+        $this->dump()->shouldBeString();
+    }
+
+    function it_can_build_with_Upstream_node(Upstream $upstream)
+    {
+        $upstream->__toString()->willReturn("upstream name {
+}");
+        $this->append($upstream);
+        $this->dump()->shouldBeString();
+    }
+}