Pass uploaded files configured with configRequest() to ServerRequest.

src/TestSuite/IntegrationTestTrait.php

@@ -621,7 +621,8 @@ trait IntegrationTestTrait
         $props = [
             'url' => $url,
             'session' => $session,
-            'query' => $queryData
+            'query' => $queryData,
+            'files' => [],
         ];
         if (is_string($data)) {
             $props['input'] = $data;

src/TestSuite/MiddlewareDispatcher.php

@@ -153,7 +153,8 @@ class MiddlewareDispatcher
             $environment,
             $spec['query'],
             $spec['post'],
-            $spec['cookies']
+            $spec['cookies'],
+            $spec['files']
         );
         $request = $request->withAttribute('session', $spec['session']);