Fix Error tests using deprecated request properties.

tests/TestCase/Error/ErrorHandlerTest.php

@@ -86,11 +86,11 @@ class ErrorHandlerTest extends TestCase
         Router::reload();
 
         $request = new ServerRequest([
+            'base' => '',
             'environment' => [
                 'HTTP_REFERER' => '/referer'
             ]
         ]);
-        $request->base = '';
 
         Router::setRequestInfo($request);
         Configure::write('debug', true);

tests/TestCase/Error/ExceptionRendererTest.php

@@ -165,8 +165,7 @@ class ExceptionRendererTest extends TestCase
         Configure::write('Config.language', 'eng');
         Router::reload();
 
-        $request = new ServerRequest();
-        $request->base = '';
+        $request = new ServerRequest(['base' => '']);
         Router::setRequestInfo($request);
         Configure::write('debug', true);
     }