Imrpove PHPUnit bootstrap
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 9a46e9d..11777b7 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -1,5 +1,12 @@
 <?php
 
-echo exec( 'composer update' ) . "\n";
+if ( php_sapi_name() !== 'cli' ) {
+	die( 'Not an entry point' );
+}
+
+$pwd = exec( 'pwd' );
+chdir( __DIR__ . '/..' );
+passthru( 'composer update' );
+chdir( $pwd );
 
 require_once( __DIR__ . '/../vendor/autoload.php' );