Address static analysis issues

Author: Riimu

.travis.yml

@@ -14,11 +14,9 @@ cache:
 
 before_install:
   - if [[ $TRAVIS_PHP_VERSION =~ ^7 ]]; then phpenv config-rm xdebug.ini; fi
-  - composer self-update
 
 install:
-  - composer require --no-update --no-interaction "phpunit/phpunit:*" "squizlabs/php_codesniffer:*" "friendsofphp/php-cs-fixer:*"
-  - travis_retry composer update --no-interaction --prefer-source
+  - travis_retry composer update --no-interaction
   - travis_retry wget https://scrutinizer-ci.com/ocular.phar
 
 before_script:

composer.json

@@ -19,6 +19,11 @@
     "php": ">=5.6.0",
     "psr/http-message": "^1.0"
   },
+  "require-dev": {
+    "phpunit/phpunit": "^6.0",
+    "squizlabs/php_codesniffer": "^2.8",
+    "friendsofphp/php-cs-fixer": "^2.1"
+  },
   "autoload": {
     "psr-4": {
       "Violet\\StreamingJsonEncoder\\": "src/"

src/AbstractJsonEncoder.php

@@ -108,7 +108,7 @@ private function initialize()
 
     /**
      * Returns the current number of step in the encoder.
-     * @return int|null The current step number or null if the current state is not valid
+     * @return mixed The current step number as integer or null if the current state is not valid
      */
     public function key()
     {

src/JsonStream.php

@@ -13,13 +13,13 @@
  */
 class JsonStream implements StreamInterface
 {
-    /** @var BufferJsonEncoder The encoder used to produce the JSON stream */
+    /** @var BufferJsonEncoder|null The encoder used to produce the JSON stream or null once closed */
     private $encoder;
 
     /** @var int The current position of the cursor in the JSON stream */
     private $cursor;
 
-    /** @var string Buffered output from encoding the value as JSON */
+    /** @var string|null Buffered output from encoding the value as JSON or null when at EOF */
     private $buffer;
 
     /**

tests/classes/SerializableData.php

@@ -11,8 +11,13 @@
  */
 class SerializableData implements \JsonSerializable
 {
+    /** @var mixed */
     private $data;
 
+    /**
+     * SerializableData constructor.
+     * @param mixed $data
+     */
     public function __construct($data)
     {
         $this->data = $data;

tests/tests/JsonStreamTest.php

@@ -128,7 +128,7 @@ public function testInvalidSeekWhence()
         $stream = new JsonStream('value');
 
         $this->expectException(\InvalidArgumentException::class);
-        $stream->seek(2, 'invalid');
+        $stream->seek(2, -1);
     }
 
     public function testPrettyPrintStream()