Add request conditional plugin

Applied fixes from StyleCI

Author: sagikazarmark

spec/RequestConditionalPluginSpec.php

@@ -0,0 +1,55 @@
+<?php
+
+namespace spec\Http\Client\Plugin;
+
+use Http\Client\Plugin\Plugin;
+use Http\Message\RequestMatcher;
+use Http\Promise\Promise;
+use Psr\Http\Message\RequestInterface;
+use PhpSpec\ObjectBehavior;
+use Prophecy\Argument;
+
+class RequestConditionalPluginSpec extends ObjectBehavior
+{
+    function let(RequestMatcher $requestMatcher, Plugin $plugin)
+    {
+        $this->beConstructedWith($requestMatcher, $plugin);
+    }
+
+    function it_is_initializable()
+    {
+        $this->shouldHaveType('Http\Client\Plugin\RequestConditionalPlugin');
+    }
+
+    function it_is_a_plugin()
+    {
+        $this->shouldImplement('Http\Client\Plugin\Plugin');
+    }
+
+    function it_matches_a_request_and_delegates_to_plugin(
+        RequestInterface $request,
+        RequestMatcher $requestMatcher,
+        Plugin $plugin
+    ) {
+        $requestMatcher->matches($request)->willReturn(true);
+        $plugin->handleRequest($request, Argument::type('callable'), Argument::type('callable'))->shouldBeCalled();
+
+        $this->handleRequest($request, function () {}, function () {});
+    }
+
+    function it_does_not_match_a_request(
+        RequestInterface $request,
+        RequestMatcher $requestMatcher,
+        Plugin $plugin,
+        Promise $promise
+    ) {
+        $requestMatcher->matches($request)->willReturn(false);
+        $plugin->handleRequest($request, Argument::type('callable'), Argument::type('callable'))->shouldNotBeCalled();
+
+        $next = function (RequestInterface $request) use($promise) {
+            return $promise->getWrappedObject();
+        };
+
+        $this->handleRequest($request, $next, function () {})->shouldReturn($promise);
+    }
+}

src/RequestConditionalPlugin.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace Http\Client\Plugin;
+
+use Http\Message\RequestMatcher;
+use Psr\Http\Message\RequestInterface;
+
+/**
+ * Apply a delegated plugin based on a request match.
+ *
+ * @author Márk Sági-Kazár <[email protected]>
+ */
+final class RequestConditionalPlugin implements Plugin
+{
+    /**
+     * @var RequestMatcher
+     */
+    private $requestMatcher;
+
+    /**
+     * @var Plugin
+     */
+    private $delegatedPlugin;
+
+    /**
+     * @param RequestMatcher $requestMatcher
+     * @param Plugin         $delegatedPlugin
+     */
+    public function __construct(RequestMatcher $requestMatcher, Plugin $delegatedPlugin)
+    {
+        $this->requestMatcher = $requestMatcher;
+        $this->delegatedPlugin = $delegatedPlugin;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function handleRequest(RequestInterface $request, callable $next, callable $first)
+    {
+        if ($this->requestMatcher->matches($request)) {
+            return $this->delegatedPlugin->handleRequest($request, $next, $first);
+        }
+
+        return $next($request);
+    }
+}