Fix phpunit config for V6

Author: mikehaertl

phpunit.xml.dist

@@ -9,7 +9,7 @@
          processIsolation="true"
          stopOnFailure="false"
          syntaxCheck="false"
-         bootstrap="vendor/autoload.php"
+         bootstrap="tests/bootstrap.php"
 >
     <testsuites>
         <testsuite name="Yii2 Config Test Suite">

tests/bootstrap.php

@@ -1 +1,10 @@
 <?php
+require __DIR__ . '/../vendor/autoload.php';
+
+// Some travis environments use phpunit > 6
+$newClass = '\PHPUnit\Framework\TestCase';
+$oldClass = '\PHPUnit_Framework_TestCase';
+if (!class_exists($newClass) && class_exists($oldClass)) {
+    class_alias($oldClass, $newClass);
+}
+