Added unit test to #977 fix + defensive approach

Author: ezimuel

src/Elasticsearch/Connections/Connection.php

@@ -685,7 +685,6 @@ private function tryDeserializeError(array $response, string $errorClass): Elast
                 // added json_encode to convert into a string
                 return new $errorClass(json_encode($response['body']), (int) $response['status']);
             }
-
             // 2.0 structured exceptions
             if (is_array($error['error']) && array_key_exists('reason', $error['error']) === true) {
                 // Try to use root cause first (only grabs the first root cause)
@@ -699,14 +698,31 @@ private function tryDeserializeError(array $response, string $errorClass): Elast
                 }
                 // added json_encode to convert into a string
                 $original = new $errorClass(json_encode($response['body']), $response['status']);
-
                 return new $errorClass("$type: $cause", (int) $response['status'], $original);
             }
             // <2.0 semi-structured exceptions
             // added json_encode to convert into a string
             $original = new $errorClass(json_encode($response['body']), $response['status']);
-
             return new $errorClass($error['error'], (int) $response['status'], $original);
+            
+            // // 2.0 structured exceptions
+            // if (is_array($error['error'])) {
+            //     // Try to use root cause first (only grabs the first root cause)
+            //     $root = $error['error']['root_cause'];
+            //     if (isset($root) && isset($root[0])) {
+            //         $cause = $root[0]['reason'];
+            //         $type = $root[0]['type'];
+            //     } else {
+            //         $cause = $error['error']['reason'];
+            //         $type = $error['error']['type'];
+            //     }
+            // }
+            // // added json_encode to convert into a string
+            // $original = new $errorClass(json_encode($response['body']), $response['status']);
+
+            // return isset($cause) && isset($type) ?
+            //     new $errorClass("$type: $cause", (int) $response['status'], $original) : 
+            //     new $errorClass(json_encode($error['error']), (int) $response['status'], $original);
         }
 
         // if responseBody is not string, we convert it so it can be used as Exception message

tests/Elasticsearch/Tests/Connections/ConnectionTest.php

@@ -6,9 +6,12 @@
 
 use Elasticsearch\Client;
 use Elasticsearch\ClientBuilder;
+use Elasticsearch\Common\Exceptions\ServerErrorResponseException;
 use Elasticsearch\Connections\Connection;
 use Elasticsearch\Serializers\SerializerInterface;
+use Elasticsearch\Serializers\SmartSerializer;
 use Psr\Log\LoggerInterface;
+use ReflectionClass;
 
 class ConnectionTest extends \PHPUnit\Framework\TestCase
 {
@@ -282,4 +285,36 @@ public function testGetHeadersContainBasicAuthOverHostArrayConfig()
         $this->assertArrayNotHasKey('Authorization', $request['headers']);
         $this->assertContains('username:password', $request['client']['curl'][CURLOPT_USERPWD]);
     }
+
+    public function testTryDeserializeErrorWithMasterNotDiscoveredException()
+    {
+        $host = [
+            'host' => 'localhost'
+        ];
+
+        $connection = new Connection(
+            function () {
+            },
+            $host,
+            [],
+            new SmartSerializer(),
+            $this->logger,
+            $this->trace
+        );
+
+        $reflection = new ReflectionClass(Connection::class);
+        $tryDeserializeError = $reflection->getMethod('tryDeserializeError');
+        $tryDeserializeError->setAccessible(true);
+
+        $body = '{"error":{"root_cause":[{"type":"master_not_discovered_exception","reason":null}],"type":"master_not_discovered_exception","reason":null},"status":503}';
+        $response = [ 
+            'transfer_stats' => [],
+            'status' => 503,
+            'body' => $body
+        ];
+
+        $result = $tryDeserializeError->invoke($connection, $response, ServerErrorResponseException::class);
+        $this->assertInstanceOf(ServerErrorResponseException::class, $result);
+        $this->assertContains('master_not_discovered_exception', $result->getMessage());
+    }
 }