diff --git a/composer.json b/composer.json
index 76cf46f9..e60948f8 100644
--- a/composer.json
+++ b/composer.json
@@ -28,7 +28,7 @@
     },
     "require-dev": {
         "bamarni/composer-bin-plugin": "^1.1",
-        "phpunit/phpunit": "^6.1"
+        "phpunit/phpunit": "^7.0"
     },
 
     "bin": ["bin/php-scoper"],
diff --git a/composer.lock b/composer.lock
index b9c90c18..7fa83668 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,20 +4,20 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "1b72b0b26957bca6e70c5c255bb842a8",
+    "content-hash": "933cff8f65fc343c4260ca48270d39c2",
     "packages": [
         {
             "name": "nikic/php-parser",
-            "version": "v3.1.4",
+            "version": "v3.1.5",
             "source": {
                 "type": "git",
                 "url": "https://github.com/nikic/PHP-Parser.git",
-                "reference": "e57b3a09784f846411aa7ed664eedb73e3399078"
+                "reference": "bb87e28e7d7b8d9a7fda231d37457c9210faf6ce"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/nikic/PHP-Parser/zipball/e57b3a09784f846411aa7ed664eedb73e3399078",
-                "reference": "e57b3a09784f846411aa7ed664eedb73e3399078",
+                "url": "https://api.github.com/repos/nikic/PHP-Parser/zipball/bb87e28e7d7b8d9a7fda231d37457c9210faf6ce",
+                "reference": "bb87e28e7d7b8d9a7fda231d37457c9210faf6ce",
                 "shasum": ""
             },
             "require": {
@@ -55,31 +55,31 @@
                 "parser",
                 "php"
             ],
-            "time": "2018-01-25T21:31:33+00:00"
+            "time": "2018-02-28T20:30:58+00:00"
         },
         {
             "name": "ocramius/package-versions",
-            "version": "1.1.3",
+            "version": "1.3.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/Ocramius/PackageVersions.git",
-                "reference": "72b226d2957e9e6a9ed09aeaa29cabd840d1a3b7"
+                "reference": "4489d5002c49d55576fa0ba786f42dbb009be46f"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/Ocramius/PackageVersions/zipball/72b226d2957e9e6a9ed09aeaa29cabd840d1a3b7",
-                "reference": "72b226d2957e9e6a9ed09aeaa29cabd840d1a3b7",
+                "url": "https://api.github.com/repos/Ocramius/PackageVersions/zipball/4489d5002c49d55576fa0ba786f42dbb009be46f",
+                "reference": "4489d5002c49d55576fa0ba786f42dbb009be46f",
                 "shasum": ""
             },
             "require": {
-                "composer-plugin-api": "^1.0",
-                "php": "~7.0"
+                "composer-plugin-api": "^1.0.0",
+                "php": "^7.1.0"
             },
             "require-dev": {
-                "composer/composer": "^1.3",
+                "composer/composer": "^1.6.3",
                 "ext-zip": "*",
-                "humbug/humbug": "dev-master",
-                "phpunit/phpunit": "^5.7.5"
+                "infection/infection": "^0.7.1",
+                "phpunit/phpunit": "^7.0.0"
             },
             "type": "composer-plugin",
             "extra": {
@@ -104,7 +104,7 @@
                 }
             ],
             "description": "Composer plugin that provides efficient querying for installed package versions (no runtime IO)",
-            "time": "2017-09-06T15:24:43+00:00"
+            "time": "2018-02-05T13:05:30+00:00"
         },
         {
             "name": "phpdocumentor/reflection-common",
@@ -162,29 +162,35 @@
         },
         {
             "name": "phpdocumentor/reflection-docblock",
-            "version": "4.1.1",
+            "version": "4.3.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpDocumentor/ReflectionDocBlock.git",
-                "reference": "2d3d238c433cf69caeb4842e97a3223a116f94b2"
+                "reference": "94fd0001232e47129dd3504189fa1c7225010d08"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpDocumentor/ReflectionDocBlock/zipball/2d3d238c433cf69caeb4842e97a3223a116f94b2",
-                "reference": "2d3d238c433cf69caeb4842e97a3223a116f94b2",
+                "url": "https://api.github.com/repos/phpDocumentor/ReflectionDocBlock/zipball/94fd0001232e47129dd3504189fa1c7225010d08",
+                "reference": "94fd0001232e47129dd3504189fa1c7225010d08",
                 "shasum": ""
             },
             "require": {
                 "php": "^7.0",
-                "phpdocumentor/reflection-common": "^1.0@dev",
+                "phpdocumentor/reflection-common": "^1.0.0",
                 "phpdocumentor/type-resolver": "^0.4.0",
                 "webmozart/assert": "^1.0"
             },
             "require-dev": {
-                "mockery/mockery": "^0.9.4",
-                "phpunit/phpunit": "^4.4"
+                "doctrine/instantiator": "~1.0.5",
+                "mockery/mockery": "^1.0",
+                "phpunit/phpunit": "^6.4"
             },
             "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "4.x-dev"
+                }
+            },
             "autoload": {
                 "psr-4": {
                     "phpDocumentor\\Reflection\\": [
@@ -203,7 +209,7 @@
                 }
             ],
             "description": "With this component, a library can provide support for annotations via DocBlocks or otherwise retrieve information that is embedded in a DocBlock.",
-            "time": "2017-08-30T18:51:59+00:00"
+            "time": "2017-11-30T07:14:17+00:00"
         },
         {
             "name": "phpdocumentor/type-resolver",
@@ -252,70 +258,23 @@
             ],
             "time": "2017-07-14T14:27:02+00:00"
         },
-        {
-            "name": "psr/log",
-            "version": "1.0.2",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/php-fig/log.git",
-                "reference": "4ebe3a8bf773a19edfe0a84b6585ba3d401b724d"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/php-fig/log/zipball/4ebe3a8bf773a19edfe0a84b6585ba3d401b724d",
-                "reference": "4ebe3a8bf773a19edfe0a84b6585ba3d401b724d",
-                "shasum": ""
-            },
-            "require": {
-                "php": ">=5.3.0"
-            },
-            "type": "library",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "1.0.x-dev"
-                }
-            },
-            "autoload": {
-                "psr-4": {
-                    "Psr\\Log\\": "Psr/Log/"
-                }
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "PHP-FIG",
-                    "homepage": "http://www.php-fig.org/"
-                }
-            ],
-            "description": "Common interface for logging libraries",
-            "homepage": "https://github.com/php-fig/log",
-            "keywords": [
-                "log",
-                "psr",
-                "psr-3"
-            ],
-            "time": "2016-10-10T12:19:37+00:00"
-        },
         {
             "name": "roave/better-reflection",
-            "version": "2.0.0",
+            "version": "2.0.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/Roave/BetterReflection.git",
-                "reference": "619be9a2cef239245d8f1f466bcddc037949b788"
+                "reference": "efc45b50cb52d5eeaacab15741376e981e28738b"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/Roave/BetterReflection/zipball/619be9a2cef239245d8f1f466bcddc037949b788",
-                "reference": "619be9a2cef239245d8f1f466bcddc037949b788",
+                "url": "https://api.github.com/repos/Roave/BetterReflection/zipball/efc45b50cb52d5eeaacab15741376e981e28738b",
+                "reference": "efc45b50cb52d5eeaacab15741376e981e28738b",
                 "shasum": ""
             },
             "require": {
                 "nikic/php-parser": "^3.1.1",
-                "php": ">7.1.0,<7.3.0",
+                "php": ">=7.1.0,<7.3.0",
                 "phpdocumentor/reflection-docblock": "^4.1.1",
                 "phpdocumentor/type-resolver": "^0.4.0",
                 "roave/signature": "^1.0"
@@ -359,7 +318,7 @@
                 }
             ],
             "description": "Better Reflection - an improved code reflection API",
-            "time": "2017-09-16T20:30:16+00:00"
+            "time": "2018-02-05T08:08:57+00:00"
         },
         {
             "name": "roave/signature",
@@ -396,44 +355,44 @@
         },
         {
             "name": "symfony/console",
-            "version": "v3.3.10",
+            "version": "v4.0.9",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/console.git",
-                "reference": "116bc56e45a8e5572e51eb43ab58c769a352366c"
+                "reference": "3e820bc2c520a87ca209ad8fa961c97f42e0b4ae"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/console/zipball/116bc56e45a8e5572e51eb43ab58c769a352366c",
-                "reference": "116bc56e45a8e5572e51eb43ab58c769a352366c",
+                "url": "https://api.github.com/repos/symfony/console/zipball/3e820bc2c520a87ca209ad8fa961c97f42e0b4ae",
+                "reference": "3e820bc2c520a87ca209ad8fa961c97f42e0b4ae",
                 "shasum": ""
             },
             "require": {
-                "php": "^5.5.9|>=7.0.8",
-                "symfony/debug": "~2.8|~3.0",
+                "php": "^7.1.3",
                 "symfony/polyfill-mbstring": "~1.0"
             },
             "conflict": {
-                "symfony/dependency-injection": "<3.3"
+                "symfony/dependency-injection": "<3.4",
+                "symfony/process": "<3.3"
             },
             "require-dev": {
                 "psr/log": "~1.0",
-                "symfony/config": "~3.3",
-                "symfony/dependency-injection": "~3.3",
-                "symfony/event-dispatcher": "~2.8|~3.0",
-                "symfony/filesystem": "~2.8|~3.0",
-                "symfony/process": "~2.8|~3.0"
+                "symfony/config": "~3.4|~4.0",
+                "symfony/dependency-injection": "~3.4|~4.0",
+                "symfony/event-dispatcher": "~3.4|~4.0",
+                "symfony/lock": "~3.4|~4.0",
+                "symfony/process": "~3.4|~4.0"
             },
             "suggest": {
-                "psr/log": "For using the console logger",
+                "psr/log-implementation": "For using the console logger",
                 "symfony/event-dispatcher": "",
-                "symfony/filesystem": "",
+                "symfony/lock": "",
                 "symfony/process": ""
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "3.3-dev"
+                    "dev-master": "4.0-dev"
                 }
             },
             "autoload": {
@@ -460,85 +419,29 @@
             ],
             "description": "Symfony Console Component",
             "homepage": "https://symfony.com",
-            "time": "2017-10-02T06:42:24+00:00"
-        },
-        {
-            "name": "symfony/debug",
-            "version": "v3.3.10",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/symfony/debug.git",
-                "reference": "eb95d9ce8f18dcc1b3dfff00cb624c402be78ffd"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/symfony/debug/zipball/eb95d9ce8f18dcc1b3dfff00cb624c402be78ffd",
-                "reference": "eb95d9ce8f18dcc1b3dfff00cb624c402be78ffd",
-                "shasum": ""
-            },
-            "require": {
-                "php": "^5.5.9|>=7.0.8",
-                "psr/log": "~1.0"
-            },
-            "conflict": {
-                "symfony/http-kernel": ">=2.3,<2.3.24|~2.4.0|>=2.5,<2.5.9|>=2.6,<2.6.2"
-            },
-            "require-dev": {
-                "symfony/http-kernel": "~2.8|~3.0"
-            },
-            "type": "library",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "3.3-dev"
-                }
-            },
-            "autoload": {
-                "psr-4": {
-                    "Symfony\\Component\\Debug\\": ""
-                },
-                "exclude-from-classmap": [
-                    "/Tests/"
-                ]
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "Fabien Potencier",
-                    "email": "fabien@symfony.com"
-                },
-                {
-                    "name": "Symfony Community",
-                    "homepage": "https://symfony.com/contributors"
-                }
-            ],
-            "description": "Symfony Debug Component",
-            "homepage": "https://symfony.com",
-            "time": "2017-10-02T06:42:24+00:00"
+            "time": "2018-04-30T01:23:47+00:00"
         },
         {
             "name": "symfony/filesystem",
-            "version": "v3.3.10",
+            "version": "v4.0.9",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/filesystem.git",
-                "reference": "90bc45abf02ae6b7deb43895c1052cb0038506f1"
+                "reference": "5d2d655b2c72fc4d9bf7e9bf14f72a447b940f21"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/filesystem/zipball/90bc45abf02ae6b7deb43895c1052cb0038506f1",
-                "reference": "90bc45abf02ae6b7deb43895c1052cb0038506f1",
+                "url": "https://api.github.com/repos/symfony/filesystem/zipball/5d2d655b2c72fc4d9bf7e9bf14f72a447b940f21",
+                "reference": "5d2d655b2c72fc4d9bf7e9bf14f72a447b940f21",
                 "shasum": ""
             },
             "require": {
-                "php": "^5.5.9|>=7.0.8"
+                "php": "^7.1.3"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "3.3-dev"
+                    "dev-master": "4.0-dev"
                 }
             },
             "autoload": {
@@ -565,29 +468,29 @@
             ],
             "description": "Symfony Filesystem Component",
             "homepage": "https://symfony.com",
-            "time": "2017-10-03T13:33:10+00:00"
+            "time": "2018-02-22T10:50:29+00:00"
         },
         {
             "name": "symfony/finder",
-            "version": "v3.3.10",
+            "version": "v4.0.9",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/finder.git",
-                "reference": "773e19a491d97926f236942484cb541560ce862d"
+                "reference": "ca27c02b7a3fef4828c998c2ff9ba7aae1641c49"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/finder/zipball/773e19a491d97926f236942484cb541560ce862d",
-                "reference": "773e19a491d97926f236942484cb541560ce862d",
+                "url": "https://api.github.com/repos/symfony/finder/zipball/ca27c02b7a3fef4828c998c2ff9ba7aae1641c49",
+                "reference": "ca27c02b7a3fef4828c998c2ff9ba7aae1641c49",
                 "shasum": ""
             },
             "require": {
-                "php": "^5.5.9|>=7.0.8"
+                "php": "^7.1.3"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "3.3-dev"
+                    "dev-master": "4.0-dev"
                 }
             },
             "autoload": {
@@ -614,20 +517,20 @@
             ],
             "description": "Symfony Finder Component",
             "homepage": "https://symfony.com",
-            "time": "2017-10-02T06:42:24+00:00"
+            "time": "2018-04-04T05:10:37+00:00"
         },
         {
             "name": "symfony/polyfill-mbstring",
-            "version": "v1.5.0",
+            "version": "v1.8.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/polyfill-mbstring.git",
-                "reference": "7c8fae0ac1d216eb54349e6a8baa57d515fe8803"
+                "reference": "3296adf6a6454a050679cde90f95350ad604b171"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/polyfill-mbstring/zipball/7c8fae0ac1d216eb54349e6a8baa57d515fe8803",
-                "reference": "7c8fae0ac1d216eb54349e6a8baa57d515fe8803",
+                "url": "https://api.github.com/repos/symfony/polyfill-mbstring/zipball/3296adf6a6454a050679cde90f95350ad604b171",
+                "reference": "3296adf6a6454a050679cde90f95350ad604b171",
                 "shasum": ""
             },
             "require": {
@@ -639,7 +542,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.5-dev"
+                    "dev-master": "1.8-dev"
                 }
             },
             "autoload": {
@@ -673,20 +576,20 @@
                 "portable",
                 "shim"
             ],
-            "time": "2017-06-14T15:44:48+00:00"
+            "time": "2018-04-26T10:06:28+00:00"
         },
         {
             "name": "webmozart/assert",
-            "version": "1.2.0",
+            "version": "1.3.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/webmozart/assert.git",
-                "reference": "2db61e59ff05fe5126d152bd0655c9ea113e550f"
+                "reference": "0df1908962e7a3071564e857d86874dad1ef204a"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/webmozart/assert/zipball/2db61e59ff05fe5126d152bd0655c9ea113e550f",
-                "reference": "2db61e59ff05fe5126d152bd0655c9ea113e550f",
+                "url": "https://api.github.com/repos/webmozart/assert/zipball/0df1908962e7a3071564e857d86874dad1ef204a",
+                "reference": "0df1908962e7a3071564e857d86874dad1ef204a",
                 "shasum": ""
             },
             "require": {
@@ -723,7 +626,7 @@
                 "check",
                 "validate"
             ],
-            "time": "2016-11-23T20:04:58+00:00"
+            "time": "2018-01-29T19:49:41+00:00"
         }
     ],
     "packages-dev": [
@@ -822,37 +725,40 @@
         },
         {
             "name": "myclabs/deep-copy",
-            "version": "1.6.1",
+            "version": "1.7.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/myclabs/DeepCopy.git",
-                "reference": "8e6e04167378abf1ddb4d3522d8755c5fd90d102"
+                "reference": "3b8a3a99ba1f6a3952ac2747d989303cbd6b7a3e"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/myclabs/DeepCopy/zipball/8e6e04167378abf1ddb4d3522d8755c5fd90d102",
-                "reference": "8e6e04167378abf1ddb4d3522d8755c5fd90d102",
+                "url": "https://api.github.com/repos/myclabs/DeepCopy/zipball/3b8a3a99ba1f6a3952ac2747d989303cbd6b7a3e",
+                "reference": "3b8a3a99ba1f6a3952ac2747d989303cbd6b7a3e",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.4.0"
+                "php": "^5.6 || ^7.0"
             },
             "require-dev": {
-                "doctrine/collections": "1.*",
-                "phpunit/phpunit": "~4.1"
+                "doctrine/collections": "^1.0",
+                "doctrine/common": "^2.6",
+                "phpunit/phpunit": "^4.1"
             },
             "type": "library",
             "autoload": {
                 "psr-4": {
                     "DeepCopy\\": "src/DeepCopy/"
-                }
+                },
+                "files": [
+                    "src/DeepCopy/deep_copy.php"
+                ]
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
                 "MIT"
             ],
             "description": "Create deep copies (clones) of your objects",
-            "homepage": "https://github.com/myclabs/DeepCopy",
             "keywords": [
                 "clone",
                 "copy",
@@ -860,7 +766,7 @@
                 "object",
                 "object graph"
             ],
-            "time": "2017-04-12T18:52:22+00:00"
+            "time": "2017-10-19T19:58:43+00:00"
         },
         {
             "name": "phar-io/manifest",
@@ -966,28 +872,28 @@
         },
         {
             "name": "phpspec/prophecy",
-            "version": "v1.7.2",
+            "version": "1.7.6",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpspec/prophecy.git",
-                "reference": "c9b8c6088acd19d769d4cc0ffa60a9fe34344bd6"
+                "reference": "33a7e3c4fda54e912ff6338c48823bd5c0f0b712"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpspec/prophecy/zipball/c9b8c6088acd19d769d4cc0ffa60a9fe34344bd6",
-                "reference": "c9b8c6088acd19d769d4cc0ffa60a9fe34344bd6",
+                "url": "https://api.github.com/repos/phpspec/prophecy/zipball/33a7e3c4fda54e912ff6338c48823bd5c0f0b712",
+                "reference": "33a7e3c4fda54e912ff6338c48823bd5c0f0b712",
                 "shasum": ""
             },
             "require": {
                 "doctrine/instantiator": "^1.0.2",
                 "php": "^5.3|^7.0",
                 "phpdocumentor/reflection-docblock": "^2.0|^3.0.2|^4.0",
-                "sebastian/comparator": "^1.1|^2.0",
+                "sebastian/comparator": "^1.1|^2.0|^3.0",
                 "sebastian/recursion-context": "^1.0|^2.0|^3.0"
             },
             "require-dev": {
                 "phpspec/phpspec": "^2.5|^3.2",
-                "phpunit/phpunit": "^4.8 || ^5.6.5"
+                "phpunit/phpunit": "^4.8.35 || ^5.7 || ^6.5"
             },
             "type": "library",
             "extra": {
@@ -1025,45 +931,44 @@
                 "spy",
                 "stub"
             ],
-            "time": "2017-09-04T11:05:03+00:00"
+            "time": "2018-04-18T13:57:24+00:00"
         },
         {
             "name": "phpunit/php-code-coverage",
-            "version": "5.2.2",
+            "version": "6.0.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/php-code-coverage.git",
-                "reference": "8ed1902a57849e117b5651fc1a5c48110946c06b"
+                "reference": "52187754b0eed0b8159f62a6fa30073327e8c2ca"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/php-code-coverage/zipball/8ed1902a57849e117b5651fc1a5c48110946c06b",
-                "reference": "8ed1902a57849e117b5651fc1a5c48110946c06b",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-code-coverage/zipball/52187754b0eed0b8159f62a6fa30073327e8c2ca",
+                "reference": "52187754b0eed0b8159f62a6fa30073327e8c2ca",
                 "shasum": ""
             },
             "require": {
                 "ext-dom": "*",
                 "ext-xmlwriter": "*",
-                "php": "^7.0",
+                "php": "^7.1",
                 "phpunit/php-file-iterator": "^1.4.2",
                 "phpunit/php-text-template": "^1.2.1",
-                "phpunit/php-token-stream": "^1.4.11 || ^2.0",
+                "phpunit/php-token-stream": "^3.0",
                 "sebastian/code-unit-reverse-lookup": "^1.0.1",
-                "sebastian/environment": "^3.0",
+                "sebastian/environment": "^3.1",
                 "sebastian/version": "^2.0.1",
                 "theseer/tokenizer": "^1.1"
             },
             "require-dev": {
-                "ext-xdebug": "^2.5",
-                "phpunit/phpunit": "^6.0"
+                "phpunit/phpunit": "^7.0"
             },
             "suggest": {
-                "ext-xdebug": "^2.5.5"
+                "ext-xdebug": "^2.6.0"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "5.2.x-dev"
+                    "dev-master": "6.0-dev"
                 }
             },
             "autoload": {
@@ -1078,7 +983,7 @@
             "authors": [
                 {
                     "name": "Sebastian Bergmann",
-                    "email": "sb@sebastian-bergmann.de",
+                    "email": "sebastian@phpunit.de",
                     "role": "lead"
                 }
             ],
@@ -1089,20 +994,20 @@
                 "testing",
                 "xunit"
             ],
-            "time": "2017-08-03T12:40:43+00:00"
+            "time": "2018-04-29T14:59:09+00:00"
         },
         {
             "name": "phpunit/php-file-iterator",
-            "version": "1.4.2",
+            "version": "1.4.5",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/php-file-iterator.git",
-                "reference": "3cc8f69b3028d0f96a9078e6295d86e9bf019be5"
+                "reference": "730b01bc3e867237eaac355e06a36b85dd93a8b4"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/php-file-iterator/zipball/3cc8f69b3028d0f96a9078e6295d86e9bf019be5",
-                "reference": "3cc8f69b3028d0f96a9078e6295d86e9bf019be5",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-file-iterator/zipball/730b01bc3e867237eaac355e06a36b85dd93a8b4",
+                "reference": "730b01bc3e867237eaac355e06a36b85dd93a8b4",
                 "shasum": ""
             },
             "require": {
@@ -1136,7 +1041,7 @@
                 "filesystem",
                 "iterator"
             ],
-            "time": "2016-10-03T07:40:28+00:00"
+            "time": "2017-11-27T13:52:08+00:00"
         },
         {
             "name": "phpunit/php-text-template",
@@ -1181,28 +1086,28 @@
         },
         {
             "name": "phpunit/php-timer",
-            "version": "1.0.9",
+            "version": "2.0.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/php-timer.git",
-                "reference": "3dcf38ca72b158baf0bc245e9184d3fdffa9c46f"
+                "reference": "8b8454ea6958c3dee38453d3bd571e023108c91f"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/php-timer/zipball/3dcf38ca72b158baf0bc245e9184d3fdffa9c46f",
-                "reference": "3dcf38ca72b158baf0bc245e9184d3fdffa9c46f",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-timer/zipball/8b8454ea6958c3dee38453d3bd571e023108c91f",
+                "reference": "8b8454ea6958c3dee38453d3bd571e023108c91f",
                 "shasum": ""
             },
             "require": {
-                "php": "^5.3.3 || ^7.0"
+                "php": "^7.1"
             },
             "require-dev": {
-                "phpunit/phpunit": "^4.8.35 || ^5.7 || ^6.0"
+                "phpunit/phpunit": "^7.0"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.0-dev"
+                    "dev-master": "2.0-dev"
                 }
             },
             "autoload": {
@@ -1217,7 +1122,7 @@
             "authors": [
                 {
                     "name": "Sebastian Bergmann",
-                    "email": "sb@sebastian-bergmann.de",
+                    "email": "sebastian@phpunit.de",
                     "role": "lead"
                 }
             ],
@@ -1226,33 +1131,33 @@
             "keywords": [
                 "timer"
             ],
-            "time": "2017-02-26T11:10:40+00:00"
+            "time": "2018-02-01T13:07:23+00:00"
         },
         {
             "name": "phpunit/php-token-stream",
-            "version": "2.0.1",
+            "version": "3.0.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/php-token-stream.git",
-                "reference": "9a02332089ac48e704c70f6cefed30c224e3c0b0"
+                "reference": "21ad88bbba7c3d93530d93994e0a33cd45f02ace"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/php-token-stream/zipball/9a02332089ac48e704c70f6cefed30c224e3c0b0",
-                "reference": "9a02332089ac48e704c70f6cefed30c224e3c0b0",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-token-stream/zipball/21ad88bbba7c3d93530d93994e0a33cd45f02ace",
+                "reference": "21ad88bbba7c3d93530d93994e0a33cd45f02ace",
                 "shasum": ""
             },
             "require": {
                 "ext-tokenizer": "*",
-                "php": "^7.0"
+                "php": "^7.1"
             },
             "require-dev": {
-                "phpunit/phpunit": "^6.2.4"
+                "phpunit/phpunit": "^7.0"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "2.0-dev"
+                    "dev-master": "3.0-dev"
                 }
             },
             "autoload": {
@@ -1275,20 +1180,20 @@
             "keywords": [
                 "tokenizer"
             ],
-            "time": "2017-08-20T05:47:52+00:00"
+            "time": "2018-02-01T13:16:43+00:00"
         },
         {
             "name": "phpunit/phpunit",
-            "version": "6.4.1",
+            "version": "7.1.5",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/phpunit.git",
-                "reference": "b770d8ba7e60295ee91d69d5a5e01ae833cac220"
+                "reference": "ca64dba53b88aba6af32aebc6b388068db95c435"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/b770d8ba7e60295ee91d69d5a5e01ae833cac220",
-                "reference": "b770d8ba7e60295ee91d69d5a5e01ae833cac220",
+                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/ca64dba53b88aba6af32aebc6b388068db95c435",
+                "reference": "ca64dba53b88aba6af32aebc6b388068db95c435",
                 "shasum": ""
             },
             "require": {
@@ -1300,15 +1205,15 @@
                 "myclabs/deep-copy": "^1.6.1",
                 "phar-io/manifest": "^1.0.1",
                 "phar-io/version": "^1.0",
-                "php": "^7.0",
+                "php": "^7.1",
                 "phpspec/prophecy": "^1.7",
-                "phpunit/php-code-coverage": "^5.2.2",
-                "phpunit/php-file-iterator": "^1.4.2",
+                "phpunit/php-code-coverage": "^6.0.1",
+                "phpunit/php-file-iterator": "^1.4.3",
                 "phpunit/php-text-template": "^1.2.1",
-                "phpunit/php-timer": "^1.0.9",
-                "phpunit/phpunit-mock-objects": "^4.0.3",
-                "sebastian/comparator": "^2.0.2",
-                "sebastian/diff": "^2.0",
+                "phpunit/php-timer": "^2.0",
+                "phpunit/phpunit-mock-objects": "^6.1.1",
+                "sebastian/comparator": "^3.0",
+                "sebastian/diff": "^3.0",
                 "sebastian/environment": "^3.1",
                 "sebastian/exporter": "^3.1",
                 "sebastian/global-state": "^2.0",
@@ -1316,16 +1221,12 @@
                 "sebastian/resource-operations": "^1.0",
                 "sebastian/version": "^2.0.1"
             },
-            "conflict": {
-                "phpdocumentor/reflection-docblock": "3.0.2",
-                "phpunit/dbunit": "<3.0"
-            },
             "require-dev": {
                 "ext-pdo": "*"
             },
             "suggest": {
                 "ext-xdebug": "*",
-                "phpunit/php-invoker": "^1.1"
+                "phpunit/php-invoker": "^2.0"
             },
             "bin": [
                 "phpunit"
@@ -1333,7 +1234,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "6.4.x-dev"
+                    "dev-master": "7.1-dev"
                 }
             },
             "autoload": {
@@ -1359,33 +1260,30 @@
                 "testing",
                 "xunit"
             ],
-            "time": "2017-10-07T17:53:53+00:00"
+            "time": "2018-04-29T15:09:19+00:00"
         },
         {
             "name": "phpunit/phpunit-mock-objects",
-            "version": "4.0.4",
+            "version": "6.1.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/phpunit-mock-objects.git",
-                "reference": "2f789b59ab89669015ad984afa350c4ec577ade0"
+                "reference": "70c740bde8fd9ea9ea295be1cd875dd7b267e157"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/phpunit-mock-objects/zipball/2f789b59ab89669015ad984afa350c4ec577ade0",
-                "reference": "2f789b59ab89669015ad984afa350c4ec577ade0",
+                "url": "https://api.github.com/repos/sebastianbergmann/phpunit-mock-objects/zipball/70c740bde8fd9ea9ea295be1cd875dd7b267e157",
+                "reference": "70c740bde8fd9ea9ea295be1cd875dd7b267e157",
                 "shasum": ""
             },
             "require": {
                 "doctrine/instantiator": "^1.0.5",
-                "php": "^7.0",
+                "php": "^7.1",
                 "phpunit/php-text-template": "^1.2.1",
-                "sebastian/exporter": "^3.0"
-            },
-            "conflict": {
-                "phpunit/phpunit": "<6.0"
+                "sebastian/exporter": "^3.1"
             },
             "require-dev": {
-                "phpunit/phpunit": "^6.0"
+                "phpunit/phpunit": "^7.0"
             },
             "suggest": {
                 "ext-soap": "*"
@@ -1393,7 +1291,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "4.0.x-dev"
+                    "dev-master": "6.1-dev"
                 }
             },
             "autoload": {
@@ -1408,7 +1306,7 @@
             "authors": [
                 {
                     "name": "Sebastian Bergmann",
-                    "email": "sb@sebastian-bergmann.de",
+                    "email": "sebastian@phpunit.de",
                     "role": "lead"
                 }
             ],
@@ -1418,7 +1316,7 @@
                 "mock",
                 "xunit"
             ],
-            "time": "2017-08-03T14:08:16+00:00"
+            "time": "2018-04-11T04:50:36+00:00"
         },
         {
             "name": "sebastian/code-unit-reverse-lookup",
@@ -1467,30 +1365,30 @@
         },
         {
             "name": "sebastian/comparator",
-            "version": "2.0.2",
+            "version": "3.0.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/comparator.git",
-                "reference": "ae068fede81d06e7bb9bb46a367210a3d3e1fe6a"
+                "reference": "ed5fd2281113729f1ebcc64d101ad66028aeb3d5"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/comparator/zipball/ae068fede81d06e7bb9bb46a367210a3d3e1fe6a",
-                "reference": "ae068fede81d06e7bb9bb46a367210a3d3e1fe6a",
+                "url": "https://api.github.com/repos/sebastianbergmann/comparator/zipball/ed5fd2281113729f1ebcc64d101ad66028aeb3d5",
+                "reference": "ed5fd2281113729f1ebcc64d101ad66028aeb3d5",
                 "shasum": ""
             },
             "require": {
-                "php": "^7.0",
-                "sebastian/diff": "^2.0",
-                "sebastian/exporter": "^3.0"
+                "php": "^7.1",
+                "sebastian/diff": "^3.0",
+                "sebastian/exporter": "^3.1"
             },
             "require-dev": {
-                "phpunit/phpunit": "^6.0"
+                "phpunit/phpunit": "^7.1"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "2.0.x-dev"
+                    "dev-master": "3.0-dev"
                 }
             },
             "autoload": {
@@ -1521,38 +1419,39 @@
                 }
             ],
             "description": "Provides the functionality to compare PHP values for equality",
-            "homepage": "http://www.github.com/sebastianbergmann/comparator",
+            "homepage": "https://github.com/sebastianbergmann/comparator",
             "keywords": [
                 "comparator",
                 "compare",
                 "equality"
             ],
-            "time": "2017-08-03T07:14:59+00:00"
+            "time": "2018-04-18T13:33:00+00:00"
         },
         {
             "name": "sebastian/diff",
-            "version": "2.0.1",
+            "version": "3.0.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/diff.git",
-                "reference": "347c1d8b49c5c3ee30c7040ea6fc446790e6bddd"
+                "reference": "e09160918c66281713f1c324c1f4c4c3037ba1e8"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/diff/zipball/347c1d8b49c5c3ee30c7040ea6fc446790e6bddd",
-                "reference": "347c1d8b49c5c3ee30c7040ea6fc446790e6bddd",
+                "url": "https://api.github.com/repos/sebastianbergmann/diff/zipball/e09160918c66281713f1c324c1f4c4c3037ba1e8",
+                "reference": "e09160918c66281713f1c324c1f4c4c3037ba1e8",
                 "shasum": ""
             },
             "require": {
-                "php": "^7.0"
+                "php": "^7.1"
             },
             "require-dev": {
-                "phpunit/phpunit": "^6.2"
+                "phpunit/phpunit": "^7.0",
+                "symfony/process": "^2 || ^3.3 || ^4"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "2.0-dev"
+                    "dev-master": "3.0-dev"
                 }
             },
             "autoload": {
@@ -1577,9 +1476,12 @@
             "description": "Diff implementation",
             "homepage": "https://github.com/sebastianbergmann/diff",
             "keywords": [
-                "diff"
+                "diff",
+                "udiff",
+                "unidiff",
+                "unified diff"
             ],
-            "time": "2017-08-03T08:09:46+00:00"
+            "time": "2018-02-01T13:45:15+00:00"
         },
         {
             "name": "sebastian/environment",
diff --git a/tests/Console/Command/AddPrefixCommandIntegrationTest.php b/tests/Console/Command/AddPrefixCommandIntegrationTest.php
index 031ea155..663322a9 100644
--- a/tests/Console/Command/AddPrefixCommandIntegrationTest.php
+++ b/tests/Console/Command/AddPrefixCommandIntegrationTest.php
@@ -14,20 +14,19 @@
 
 namespace Humbug\PhpScoper\Console\Command;
 
-use PHPUnit\Framework\TestCase;
+use Humbug\PhpScoper\FileSystemTestCase;
 use Symfony\Component\Console\Tester\ApplicationTester;
 use Symfony\Component\Finder\Finder;
 use Symfony\Component\Finder\SplFileInfo;
 use function Humbug\PhpScoper\create_application;
-use function Humbug\PhpScoper\make_tmp_dir;
-use function Humbug\PhpScoper\remove_dir;
 
 /**
  * @coversNothing
  *
  * @group integration
+ * @runTestsInSeparateProcesses
  */
-class AddPrefixCommandIntegrationTest extends TestCase
+class AddPrefixCommandIntegrationTest extends FileSystemTestCase
 {
     private const FIXTURE_PATH = __DIR__.'/../../../fixtures/set002/original';
 
@@ -36,26 +35,12 @@ class AddPrefixCommandIntegrationTest extends TestCase
      */
     private $appTester;
 
-    /**
-     * @var string
-     */
-    private $cwd;
-
-    /**
-     * @var string
-     */
-    private $tmp;
-
     /**
      * @inheritdoc
      */
-    protected function setUp()
+    protected function setUp(): void
     {
-        if (null !== $this->appTester) {
-            chdir($this->tmp);
-
-            return;
-        }
+        parent::setUp();
 
         $application = create_application();
         $application->setAutoExit(false);
@@ -63,23 +48,9 @@ protected function setUp()
 
         $this->appTester = new ApplicationTester($application);
 
-        $this->cwd = getcwd();
-        $this->tmp = make_tmp_dir('scoper', __CLASS__);
-
-        chdir($this->tmp);
         file_put_contents('scoper.inc.php', '<?php return [];');
     }
 
-    /**
-     * @inheritdoc
-     */
-    protected function tearDown()
-    {
-        chdir($this->cwd);
-
-        remove_dir($this->tmp);
-    }
-
     public function test_scope_the_given_paths()
     {
         $input = [
diff --git a/tests/Console/Command/AddPrefixCommandTest.php b/tests/Console/Command/AddPrefixCommandTest.php
index d1ca28ab..469d8cef 100644
--- a/tests/Console/Command/AddPrefixCommandTest.php
+++ b/tests/Console/Command/AddPrefixCommandTest.php
@@ -15,9 +15,9 @@
 namespace Humbug\PhpScoper\Console\Command;
 
 use Humbug\PhpScoper\Console\Application;
+use Humbug\PhpScoper\FileSystemTestCase;
 use Humbug\PhpScoper\Scoper;
 use InvalidArgumentException;
-use PHPUnit\Framework\TestCase;
 use Prophecy\Argument;
 use Prophecy\Prophecy\ObjectProphecy;
 use Symfony\Component\Console\Exception\RuntimeException;
@@ -25,13 +25,12 @@
 use Symfony\Component\Filesystem\Filesystem;
 use function file_get_contents;
 use function Humbug\PhpScoper\escape_path;
-use function Humbug\PhpScoper\make_tmp_dir;
-use function Humbug\PhpScoper\remove_dir;
 
 /**
  * @covers \Humbug\PhpScoper\Console\Command\AddPrefixCommand
+ * @runTestsInSeparateProcesses
  */
-class AddPrefixCommandTest extends TestCase
+class AddPrefixCommandTest extends FileSystemTestCase
 {
     private const FIXTURE_PATH = __DIR__.'/../../../fixtures';
 
@@ -40,16 +39,6 @@ class AddPrefixCommandTest extends TestCase
      */
     private $appTester;
 
-    /**
-     * @var string
-     */
-    private $cwd;
-
-    /**
-     * @var string
-     */
-    private $tmp;
-
     /**
      * @var Filesystem|ObjectProphecy
      */
@@ -63,34 +52,15 @@ class AddPrefixCommandTest extends TestCase
     /**
      * @inheritdoc
      */
-    protected function setUp()
+    protected function setUp(): void
     {
-        if (null !== $this->appTester) {
-            chdir($this->tmp);
-
-            return;
-        }
-
-        $this->cwd = getcwd();
-        $this->tmp = make_tmp_dir('scoper', __CLASS__);
+        parent::setUp();
 
         $this->fileSystemProphecy = $this->prophesize(Filesystem::class);
 
         $this->scoperProphecy = $this->prophesize(Scoper::class);
 
         $this->appTester = $this->createAppTester();
-
-        chdir($this->tmp);
-    }
-
-    /**
-     * @inheritdoc
-     */
-    protected function tearDown()
-    {
-        chdir($this->cwd);
-
-        remove_dir($this->tmp);
     }
 
     public function test_get_help_menu()
diff --git a/tests/FileSystemTestCase.php b/tests/FileSystemTestCase.php
new file mode 100644
index 00000000..ccb168e1
--- /dev/null
+++ b/tests/FileSystemTestCase.php
@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the humbug/php-scoper package.
+ *
+ * Copyright (c) 2017 Théo FIDRY <theo.fidry@gmail.com>,
+ *                    Pádraic Brady <padraic.brady@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Humbug\PhpScoper;
+
+use PHPUnit\Framework\TestCase;
+
+abstract class FileSystemTestCase extends TestCase
+{
+    /**
+     * @var string
+     */
+    protected $cwd;
+
+    /**
+     * @var string
+     */
+    protected $tmp;
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        // Cleans up whatever was there before. Indeed upon failure PHPUnit fails to trigger the `tearDown()` method
+        // and as a result some temporary files may still remain.
+        remove_dir(str_replace('\\', '/', realpath(sys_get_temp_dir())).'/php-scoper');
+
+        $this->cwd = getcwd();
+        $this->tmp = make_tmp_dir('php-scoper', __CLASS__);
+
+        chdir($this->tmp);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function tearDown(): void
+    {
+        parent::tearDown();
+
+        chdir($this->cwd);
+
+        remove_dir($this->tmp);
+    }
+}