[tests] Fix version check to work on Redis < 2.6.0.

INFO does not have the concept of sections prior to 2.6.0 while our
test suite can be run against 2.4.0 (provided that phpunit.xml uses
the correct server profile), so we need to make sure that the check
does not break with prior version of Redis even if this is unlikely
to happen at this point.

Also changed a bit the naming of variables since things are already
pretty much explicit in this context.

tests/PHPUnit/CommandTestCase.php

@@ -160,30 +160,28 @@ abstract class CommandTestCase extends StandardTestCase
     }
 
     /**
-     * @param  string $expectedRedisVersion
+     * @param  string $expectedVersion
      * @param  string $message Optional message.
      * @throws \RuntimeException when unable to retrieve server info or redis version
      * @throws \PHPUnit_Framework_SkippedTestError when expected redis version is not met
      */
-    protected function markTestSkippedOnRedisVersionBelow($expectedRedisVersion, $message = '')
+    protected function markTestSkippedOnRedisVersionBelow($expectedVersion, $message = '')
     {
         $client = $this->getClient();
-        $serverInfo = $client->info('SERVER');
-        $serverInfo = array_change_key_case($serverInfo);
-        if (!isset($serverInfo['server'])
-            || !isset($serverInfo['server']['redis_version']))
-        {
+        $info = array_change_key_case($client->info());
+
+        if (isset($info['server']['redis_version'])) {
+            // Redis >= 2.6
+            $version = $info['server']['redis_version'];
+        } else if (isset($info['redis_version'])) {
+            // Redis < 2.6
+            $version = $info['redis_version'];
+        } else {
             throw new \RuntimeException('Unable to retrieve server info');
         }
-        $serverVersion = $serverInfo['server']['redis_version'];
-        if (version_compare($serverVersion, $expectedRedisVersion) <= -1) {
-            if ($message === '') {
-                $message = sprintf(
-                    'Test skipped as required Redis version %s was not met.',
-                    $expectedRedisVersion
-                );
-            }
-            throw new \PHPUnit_Framework_SkippedTestError($message);
+
+        if (version_compare($version, $expectedVersion) <= -1) {
+            $this->markTestSkipped($message ?: "Test requires Redis $expectedVersion, current is $version.");
         }
     }