diff --git a/.travis.yml b/.travis.yml
index f433bdd..06a451c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,7 +3,6 @@ language: php
 sudo: false
 
 php:
-  - 7.0
   - 7.1
   - 7.2
   - 7.3
@@ -40,7 +39,7 @@ before_script:
   - mkdir -p build/logs
 
 script:
-  - ./vendor/bin/phpunit --stop-on-error --stop-on-failure --coverage-clover build/logs/clover.xml
+    - vendor/bin/phpunit --coverage-clover build/logs/clover.xml
 
 after_script:
   - test -e build/logs/clover.xml && wget https://scrutinizer-ci.com/ocular.phar
diff --git a/composer.json b/composer.json
index c27e252..b528479 100644
--- a/composer.json
+++ b/composer.json
@@ -10,13 +10,13 @@
         }
     ],
     "require" : {
-        "php": ">=7.0",
+        "php": "^7.1",
         "swiftmailer/swiftmailer": "^5.1 || ^6.0",
         "tijsverkoyen/css-to-inline-styles": "^2.1"
     },
     "require-dev" : {
-        "phpunit/phpunit": "^5.7.10 || ^6.0",
-        "symfony/css-selector": "^2.0.5|^3.0"
+        "symfony/css-selector": "^2.0.5|^3.0",
+        "phpunit/phpunit": "^7"
     },
     "autoload": {
         "psr-4": {
@@ -30,7 +30,7 @@
     },
     "config": {
         "platform": {
-            "php": "7.0"
+            "php": "7.1.8"
         }
     }
 }
diff --git a/composer.lock b/composer.lock
index d990909..661af60 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "715f4c327c80b7b0441f58e86cb27fe1",
+    "content-hash": "0bde068fe95a4146f695e90275021def",
     "packages": [
         {
             "name": "doctrine/lexer",
@@ -280,32 +280,34 @@
     "packages-dev": [
         {
             "name": "doctrine/instantiator",
-            "version": "1.0.5",
+            "version": "1.3.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/doctrine/instantiator.git",
-                "reference": "8e884e78f9f0eb1329e445619e04456e64d8051d"
+                "reference": "ae466f726242e637cebdd526a7d991b9433bacf1"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/doctrine/instantiator/zipball/8e884e78f9f0eb1329e445619e04456e64d8051d",
-                "reference": "8e884e78f9f0eb1329e445619e04456e64d8051d",
+                "url": "https://api.github.com/repos/doctrine/instantiator/zipball/ae466f726242e637cebdd526a7d991b9433bacf1",
+                "reference": "ae466f726242e637cebdd526a7d991b9433bacf1",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.3,<8.0-DEV"
+                "php": "^7.1"
             },
             "require-dev": {
-                "athletic/athletic": "~0.1.8",
+                "doctrine/coding-standard": "^6.0",
                 "ext-pdo": "*",
                 "ext-phar": "*",
-                "phpunit/phpunit": "~4.0",
-                "squizlabs/php_codesniffer": "~2.0"
+                "phpbench/phpbench": "^0.13",
+                "phpstan/phpstan-phpunit": "^0.11",
+                "phpstan/phpstan-shim": "^0.11",
+                "phpunit/phpunit": "^7.0"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.0.x-dev"
+                    "dev-master": "1.2.x-dev"
                 }
             },
             "autoload": {
@@ -325,34 +327,37 @@
                 }
             ],
             "description": "A small, lightweight utility to instantiate objects in PHP without invoking their constructors",
-            "homepage": "https://github.com/doctrine/instantiator",
+            "homepage": "https://www.doctrine-project.org/projects/instantiator.html",
             "keywords": [
                 "constructor",
                 "instantiate"
             ],
-            "time": "2015-06-14T21:17:01+00:00"
+            "time": "2019-10-21T16:45:58+00:00"
         },
         {
             "name": "myclabs/deep-copy",
-            "version": "1.7.0",
+            "version": "1.9.5",
             "source": {
                 "type": "git",
                 "url": "https://github.com/myclabs/DeepCopy.git",
-                "reference": "3b8a3a99ba1f6a3952ac2747d989303cbd6b7a3e"
+                "reference": "b2c28789e80a97badd14145fda39b545d83ca3ef"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/myclabs/DeepCopy/zipball/3b8a3a99ba1f6a3952ac2747d989303cbd6b7a3e",
-                "reference": "3b8a3a99ba1f6a3952ac2747d989303cbd6b7a3e",
+                "url": "https://api.github.com/repos/myclabs/DeepCopy/zipball/b2c28789e80a97badd14145fda39b545d83ca3ef",
+                "reference": "b2c28789e80a97badd14145fda39b545d83ca3ef",
                 "shasum": ""
             },
             "require": {
-                "php": "^5.6 || ^7.0"
+                "php": "^7.1"
+            },
+            "replace": {
+                "myclabs/deep-copy": "self.version"
             },
             "require-dev": {
                 "doctrine/collections": "^1.0",
                 "doctrine/common": "^2.6",
-                "phpunit/phpunit": "^4.1"
+                "phpunit/phpunit": "^7.1"
             },
             "type": "library",
             "autoload": {
@@ -375,26 +380,26 @@
                 "object",
                 "object graph"
             ],
-            "time": "2017-10-19T19:58:43+00:00"
+            "time": "2020-01-17T21:11:47+00:00"
         },
         {
             "name": "phar-io/manifest",
-            "version": "1.0.1",
+            "version": "1.0.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phar-io/manifest.git",
-                "reference": "2df402786ab5368a0169091f61a7c1e0eb6852d0"
+                "reference": "7761fcacf03b4d4f16e7ccb606d4879ca431fcf4"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phar-io/manifest/zipball/2df402786ab5368a0169091f61a7c1e0eb6852d0",
-                "reference": "2df402786ab5368a0169091f61a7c1e0eb6852d0",
+                "url": "https://api.github.com/repos/phar-io/manifest/zipball/7761fcacf03b4d4f16e7ccb606d4879ca431fcf4",
+                "reference": "7761fcacf03b4d4f16e7ccb606d4879ca431fcf4",
                 "shasum": ""
             },
             "require": {
                 "ext-dom": "*",
                 "ext-phar": "*",
-                "phar-io/version": "^1.0.1",
+                "phar-io/version": "^2.0",
                 "php": "^5.6 || ^7.0"
             },
             "type": "library",
@@ -430,20 +435,20 @@
                 }
             ],
             "description": "Component for reading phar.io manifest information from a PHP Archive (PHAR)",
-            "time": "2017-03-05T18:14:27+00:00"
+            "time": "2018-07-08T19:23:20+00:00"
         },
         {
             "name": "phar-io/version",
-            "version": "1.0.1",
+            "version": "2.0.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phar-io/version.git",
-                "reference": "a70c0ced4be299a63d32fa96d9281d03e94041df"
+                "reference": "45a2ec53a73c70ce41d55cedef9063630abaf1b6"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phar-io/version/zipball/a70c0ced4be299a63d32fa96d9281d03e94041df",
-                "reference": "a70c0ced4be299a63d32fa96d9281d03e94041df",
+                "url": "https://api.github.com/repos/phar-io/version/zipball/45a2ec53a73c70ce41d55cedef9063630abaf1b6",
+                "reference": "45a2ec53a73c70ce41d55cedef9063630abaf1b6",
                 "shasum": ""
             },
             "require": {
@@ -477,39 +482,37 @@
                 }
             ],
             "description": "Library for handling version information and constraints",
-            "time": "2017-03-05T17:38:23+00:00"
+            "time": "2018-07-08T19:19:57+00:00"
         },
         {
             "name": "phpdocumentor/reflection-common",
-            "version": "1.0.1",
+            "version": "2.0.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpDocumentor/ReflectionCommon.git",
-                "reference": "21bdeb5f65d7ebf9f43b1b25d404f87deab5bfb6"
+                "reference": "63a995caa1ca9e5590304cd845c15ad6d482a62a"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpDocumentor/ReflectionCommon/zipball/21bdeb5f65d7ebf9f43b1b25d404f87deab5bfb6",
-                "reference": "21bdeb5f65d7ebf9f43b1b25d404f87deab5bfb6",
+                "url": "https://api.github.com/repos/phpDocumentor/ReflectionCommon/zipball/63a995caa1ca9e5590304cd845c15ad6d482a62a",
+                "reference": "63a995caa1ca9e5590304cd845c15ad6d482a62a",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.5"
+                "php": ">=7.1"
             },
             "require-dev": {
-                "phpunit/phpunit": "^4.6"
+                "phpunit/phpunit": "~6"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.0.x-dev"
+                    "dev-master": "2.x-dev"
                 }
             },
             "autoload": {
                 "psr-4": {
-                    "phpDocumentor\\Reflection\\": [
-                        "src"
-                    ]
+                    "phpDocumentor\\Reflection\\": "src/"
                 }
             },
             "notification-url": "https://packagist.org/downloads/",
@@ -531,31 +534,32 @@
                 "reflection",
                 "static analysis"
             ],
-            "time": "2017-09-11T18:02:19+00:00"
+            "time": "2018-08-07T13:53:10+00:00"
         },
         {
             "name": "phpdocumentor/reflection-docblock",
-            "version": "4.3.0",
+            "version": "4.3.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpDocumentor/ReflectionDocBlock.git",
-                "reference": "94fd0001232e47129dd3504189fa1c7225010d08"
+                "reference": "da3fd972d6bafd628114f7e7e036f45944b62e9c"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpDocumentor/ReflectionDocBlock/zipball/94fd0001232e47129dd3504189fa1c7225010d08",
-                "reference": "94fd0001232e47129dd3504189fa1c7225010d08",
+                "url": "https://api.github.com/repos/phpDocumentor/ReflectionDocBlock/zipball/da3fd972d6bafd628114f7e7e036f45944b62e9c",
+                "reference": "da3fd972d6bafd628114f7e7e036f45944b62e9c",
                 "shasum": ""
             },
             "require": {
                 "php": "^7.0",
-                "phpdocumentor/reflection-common": "^1.0.0",
-                "phpdocumentor/type-resolver": "^0.4.0",
+                "phpdocumentor/reflection-common": "^1.0.0 || ^2.0.0",
+                "phpdocumentor/type-resolver": "~0.4 || ^1.0.0",
                 "webmozart/assert": "^1.0"
             },
             "require-dev": {
-                "doctrine/instantiator": "~1.0.5",
+                "doctrine/instantiator": "^1.0.5",
                 "mockery/mockery": "^1.0",
+                "phpdocumentor/type-resolver": "0.4.*",
                 "phpunit/phpunit": "^6.4"
             },
             "type": "library",
@@ -582,41 +586,40 @@
                 }
             ],
             "description": "With this component, a library can provide support for annotations via DocBlocks or otherwise retrieve information that is embedded in a DocBlock.",
-            "time": "2017-11-30T07:14:17+00:00"
+            "time": "2019-12-28T18:55:12+00:00"
         },
         {
             "name": "phpdocumentor/type-resolver",
-            "version": "0.4.0",
+            "version": "1.0.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpDocumentor/TypeResolver.git",
-                "reference": "9c977708995954784726e25d0cd1dddf4e65b0f7"
+                "reference": "2e32a6d48972b2c1976ed5d8967145b6cec4a4a9"
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-                "reference": "9c977708995954784726e25d0cd1dddf4e65b0f7",
+                "url": "https://api.github.com/repos/phpDocumentor/TypeResolver/zipball/2e32a6d48972b2c1976ed5d8967145b6cec4a4a9",
+                "reference": "2e32a6d48972b2c1976ed5d8967145b6cec4a4a9",
                 "shasum": ""
             },
             "require": {
-                "php": "^5.5 || ^7.0",
-                "phpdocumentor/reflection-common": "^1.0"
+                "php": "^7.1",
+                "phpdocumentor/reflection-common": "^2.0"
             },
             "require-dev": {
-                "mockery/mockery": "^0.9.4",
-                "phpunit/phpunit": "^5.2||^4.8.24"
+                "ext-tokenizer": "^7.1",
+                "mockery/mockery": "~1",
+                "phpunit/phpunit": "^7.0"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.0.x-dev"
+                    "dev-master": "1.x-dev"
                 }
             },
             "autoload": {
                 "psr-4": {
-                    "phpDocumentor\\Reflection\\": [
-                        "src/"
-                    ]
+                    "phpDocumentor\\Reflection\\": "src"
                 }
             },
             "notification-url": "https://packagist.org/downloads/",
@@ -629,42 +632,43 @@
                     "email": "me@mikevanriel.com"
                 }
             ],
-            "time": "2017-07-14T14:27:02+00:00"
+            "description": "A PSR-5 based resolver of Class names, Types and Structural Element Names",
+            "time": "2019-08-22T18:11:29+00:00"
         },
         {
             "name": "phpspec/prophecy",
-            "version": "1.8.0",
+            "version": "v1.10.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpspec/prophecy.git",
-                "reference": "4ba436b55987b4bf311cb7c6ba82aa528aac0a06"
+                "reference": "b4400efc9d206e83138e2bb97ed7f5b14b831cd9"
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             "dist": {
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-                "url": "https://api.github.com/repos/phpspec/prophecy/zipball/4ba436b55987b4bf311cb7c6ba82aa528aac0a06",
-                "reference": "4ba436b55987b4bf311cb7c6ba82aa528aac0a06",
+                "url": "https://api.github.com/repos/phpspec/prophecy/zipball/b4400efc9d206e83138e2bb97ed7f5b14b831cd9",
+                "reference": "b4400efc9d206e83138e2bb97ed7f5b14b831cd9",
                 "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|^3.0",
-                "sebastian/recursion-context": "^1.0|^2.0|^3.0"
+                "phpdocumentor/reflection-docblock": "^2.0|^3.0.2|^4.0|^5.0",
+                "sebastian/comparator": "^1.2.3|^2.0|^3.0|^4.0",
+                "sebastian/recursion-context": "^1.0|^2.0|^3.0|^4.0"
             },
             "require-dev": {
-                "phpspec/phpspec": "^2.5|^3.2",
+                "phpspec/phpspec": "^2.5 || ^3.2",
                 "phpunit/phpunit": "^4.8.35 || ^5.7 || ^6.5 || ^7.1"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.8.x-dev"
+                    "dev-master": "1.10.x-dev"
                 }
             },
             "autoload": {
-                "psr-0": {
-                    "Prophecy\\": "src/"
+                "psr-4": {
+                    "Prophecy\\": "src/Prophecy"
                 }
             },
             "notification-url": "https://packagist.org/downloads/",
@@ -692,44 +696,44 @@
                 "spy",
                 "stub"
             ],
-            "time": "2018-08-05T17:53:17+00:00"
+            "time": "2020-01-20T15:57:02+00:00"
         },
         {
             "name": "phpunit/php-code-coverage",
-            "version": "5.3.2",
+            "version": "6.1.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/php-code-coverage.git",
-                "reference": "c89677919c5dd6d3b3852f230a663118762218ac"
+                "reference": "807e6013b00af69b6c5d9ceb4282d0393dbb9d8d"
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             "dist": {
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-                "reference": "c89677919c5dd6d3b3852f230a663118762218ac",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-code-coverage/zipball/807e6013b00af69b6c5d9ceb4282d0393dbb9d8d",
+                "reference": "807e6013b00af69b6c5d9ceb4282d0393dbb9d8d",
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             "require": {
                 "ext-dom": "*",
                 "ext-xmlwriter": "*",
-                "php": "^7.0",
-                "phpunit/php-file-iterator": "^1.4.2",
+                "php": "^7.1",
+                "phpunit/php-file-iterator": "^2.0",
                 "phpunit/php-text-template": "^1.2.1",
-                "phpunit/php-token-stream": "^2.0.1",
+                "phpunit/php-token-stream": "^3.0",
                 "sebastian/code-unit-reverse-lookup": "^1.0.1",
-                "sebastian/environment": "^3.0",
+                "sebastian/environment": "^3.1 || ^4.0",
                 "sebastian/version": "^2.0.1",
                 "theseer/tokenizer": "^1.1"
             },
             "require-dev": {
-                "phpunit/phpunit": "^6.0"
+                "phpunit/phpunit": "^7.0"
             },
             "suggest": {
-                "ext-xdebug": "^2.5.5"
+                "ext-xdebug": "^2.6.0"
             },
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             "extra": {
                 "branch-alias": {
-                    "dev-master": "5.3.x-dev"
+                    "dev-master": "6.1-dev"
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@@ -755,29 +759,32 @@
                 "testing",
                 "xunit"
             ],
-            "time": "2018-04-06T15:36:58+00:00"
+            "time": "2018-10-31T16:06:48+00:00"
         },
         {
             "name": "phpunit/php-file-iterator",
-            "version": "1.4.5",
+            "version": "2.0.2",
             "source": {
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                 "url": "https://github.com/sebastianbergmann/php-file-iterator.git",
-                "reference": "730b01bc3e867237eaac355e06a36b85dd93a8b4"
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+                "reference": "050bedf145a257b1ff02746c31894800e5122946",
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             },
             "require": {
-                "php": ">=5.3.3"
+                "php": "^7.1"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^7.1"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.4.x-dev"
+                    "dev-master": "2.0.x-dev"
                 }
             },
             "autoload": {
@@ -792,7 +799,7 @@
             "authors": [
                 {
                     "name": "Sebastian Bergmann",
-                    "email": "sb@sebastian-bergmann.de",
+                    "email": "sebastian@phpunit.de",
                     "role": "lead"
                 }
             ],
@@ -802,7 +809,7 @@
                 "filesystem",
                 "iterator"
             ],
-            "time": "2017-11-27T13:52:08+00:00"
+            "time": "2018-09-13T20:33:42+00:00"
         },
         {
             "name": "phpunit/php-text-template",
@@ -847,28 +854,28 @@
         },
         {
             "name": "phpunit/php-timer",
-            "version": "1.0.9",
+            "version": "2.1.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/php-timer.git",
-                "reference": "3dcf38ca72b158baf0bc245e9184d3fdffa9c46f"
+                "reference": "1038454804406b0b5f5f520358e78c1c2f71501e"
             },
             "dist": {
                 "type": "zip",
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             "require": {
-                "php": "^5.3.3 || ^7.0"
+                "php": "^5.3.3 || ^7.0",
+                "symfony/polyfill-ctype": "^1.8"
+            },
+            "conflict": {
+                "vimeo/psalm": "<3.6.0"
             },
             "require-dev": {
-                "phpunit/phpunit": "^4.6",
-                "sebastian/version": "^1.0.1"
+                "phpunit/phpunit": "^4.8.36 || ^7.5.13"
             },
             "type": "library",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "1.3-dev"
-                }
-            },
             "autoload": {
                 "psr-4": {
                     "Webmozart\\Assert\\": "src/"
@@ -1733,7 +1744,7 @@
                 "check",
                 "validate"
             ],
-            "time": "2018-01-29T19:49:41+00:00"
+            "time": "2019-11-24T13:36:37+00:00"
         }
     ],
     "aliases": [],
@@ -1742,10 +1753,10 @@
     "prefer-stable": false,
     "prefer-lowest": false,
     "platform": {
-        "php": ">=7.0"
+        "php": "^7.1"
     },
     "platform-dev": [],
     "platform-overrides": {
-        "php": "7.0"
+        "php": "7.1.8"
     }
 }
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 2a4d3fc..3c3672f 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -4,7 +4,7 @@
  backupGlobals="false"
  forceCoversAnnotation="true">
   <testsuites>
-    <testsuite>
+    <testsuite name="RootTestSuite">
       <directory>tests/src</directory>
     </testsuite>
   </testsuites>
diff --git a/tests/src/CssInlinerPluginTest.php b/tests/src/CssInlinerPluginTest.php
index 0b4d7f4..3aed2ea 100644
--- a/tests/src/CssInlinerPluginTest.php
+++ b/tests/src/CssInlinerPluginTest.php
@@ -9,7 +9,7 @@
 use Swift_NullTransport;
 
 /**
- * @coversDefaultClass Openbuildings\Swiftmailer\CssInlinerPlugin
+ * @coversDefaultClass \Openbuildings\Swiftmailer\CssInlinerPlugin
  */
 class CssInlinerPluginTest extends TestCase
 {