Ensure tests run on lowest dependencies

PHPUnit 5.7 does not namespace the ExpectationFailedException, so we
need to conditionally alias it to the non-namespaced version for tests
to run.

Author: weierophinney

.travis.yml

@@ -25,7 +25,7 @@ matrix:
       env:
         - DEPS=locked
         - TEST_COVERAGE=true
-        - LEGACY_DEPS="phpunit/phpunit"
+        - LEGACY_DEPS="phpunit/phpunit zendframework/zend-code"
     - php: 5.6
       env:
         - DEPS=latest
@@ -36,7 +36,7 @@ matrix:
       env:
         - DEPS=locked
         - CS_CHECK=true
-        - LEGACY_DEPS="phpunit/phpunit"
+        - LEGACY_DEPS="phpunit/phpunit zendframework/zend-code"
     - php: 7
       env:
         - DEPS=latest

composer.json

@@ -17,6 +17,7 @@
             "ZendTest\\XmlRpc\\": "test/"
         },
         "files": [
+            "test/autoload.php",
             "test/TestAsset/functions.php"
         ]
     },

test/autoload.php

@@ -0,0 +1,17 @@
+<?php
+/**
+ * @see       https://github.com/zendframework/zend-xmlrpc for the canonical source repository
+ * @copyright Copyright (c) 2018 Zend Technologies USA Inc. (https://www.zend.com)
+ * @license   https://github.com/zendframework/zend-xmlrpc/blob/master/LICENSE.md New BSD License
+ */
+
+/**
+ * @todo This file may be removed once we drop support for PHP 5.
+ */
+if (! class_exists(PHPUnit\Framework\ExpectationFailedException::class)) {
+    class_alias(
+        PHPUnit_Framework_ExpectationFailedException::class,
+        PHPUnit\Framework\ExpectationFailedException::class,
+        true
+    );
+}