diff --git a/composer.json b/composer.json
index 6048403..fedec54 100644
--- a/composer.json
+++ b/composer.json
@@ -21,14 +21,14 @@
         }
     },
     "require": {
-        "php": "^7.1",
+        "php": "^5.6|^7.2",
         "friendsofphp/php-cs-fixer": "^2.1",
-        "phpunit/phpunit": "~6.0|~7.0",
+        "phpunit/phpunit": "^3.7|~6.0|~7.0|~8",
         "squizlabs/php_codesniffer": "~3.0",
-        "phpmd/phpmd": "~2.6",
-        "symfony/dependency-injection": "~4.0",
-        "symfony/config": "~4.0",
-        "symfony/yaml": "~4.0",
+        "phpmd/phpmd": "*",
+        "symfony/dependency-injection": "~3.0|~4.0",
+        "symfony/config": "*",
+        "symfony/yaml": "*",
         "fiunchinho/phpunit-randomizer": "~3.0|~4.0",
         "seld/jsonlint": "~1.5",
         "bruli/ignore-files": "~1.0",
@@ -39,7 +39,7 @@
     },
     "require-dev": {
         "fzaninotto/faker": "^1.6",
-        "mockery/mockery": "~0.9",
+        "mockery/mockery": "~0.9|~1",
         "composer/composer": "^1.4"
     },
     "config": {
diff --git a/src/PhpGitHooks/Module/Composer/Tests/Behaviour/ComposerToolHandlerTest.php b/src/PhpGitHooks/Module/Composer/Tests/Behaviour/ComposerToolHandlerTest.php
index 49d40e4..5dfbdcc 100644
--- a/src/PhpGitHooks/Module/Composer/Tests/Behaviour/ComposerToolHandlerTest.php
+++ b/src/PhpGitHooks/Module/Composer/Tests/Behaviour/ComposerToolHandlerTest.php
@@ -24,7 +24,7 @@ class ComposerToolHandlerTest extends ComposerUnitTestCase
      */
     private $errorMessage;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->errorMessage = PreCommitResponseStub::FIX_YOUR_CODE;
         $this->composerToolCommandHandler = new ComposerToolHandler(
diff --git a/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/CommitMsgProcessorTest.php b/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/CommitMsgProcessorTest.php
index 94195d6..8b3956c 100644
--- a/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/CommitMsgProcessorTest.php
+++ b/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/CommitMsgProcessorTest.php
@@ -14,7 +14,7 @@ class CommitMsgProcessorTest extends ConfigurationUnitTestCase
      */
     private $commitMsgProcessor;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->commitMsgProcessor = new CommitMsgProcessor();
     }
diff --git a/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/ConfigurationDataFinderHandlerTest.php b/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/ConfigurationDataFinderHandlerTest.php
index 620a0f6..874270a 100644
--- a/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/ConfigurationDataFinderHandlerTest.php
+++ b/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/ConfigurationDataFinderHandlerTest.php
@@ -18,7 +18,7 @@ class ConfigurationDataFinderHandlerTest extends ConfigurationUnitTestCase
      */
     private $configurationDataFinderQueryHandler;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->configurationDataFinderQueryHandler = new ConfigurationDataFinderHandler(
             $this->getConfigurationFileReader()
diff --git a/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/ConfigurationProcessorHandlerTest.php b/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/ConfigurationProcessorHandlerTest.php
index 98acfa4..24702d5 100644
--- a/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/ConfigurationProcessorHandlerTest.php
+++ b/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/ConfigurationProcessorHandlerTest.php
@@ -28,7 +28,7 @@ final class ConfigurationProcessorHandlerTest extends ConfigurationUnitTestCase
      */
     private $configurationProcessorCommandHandler;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->configurationProcessorCommandHandler = new ConfigurationProcessorHandler(
             $this->getConfigurationFileReader(),
diff --git a/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/PhpGuardCoverageGitIgnoreConfiguratorTest.php b/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/PhpGuardCoverageGitIgnoreConfiguratorTest.php
index 2465c8d..e67c90e 100644
--- a/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/PhpGuardCoverageGitIgnoreConfiguratorTest.php
+++ b/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/PhpGuardCoverageGitIgnoreConfiguratorTest.php
@@ -15,7 +15,7 @@ class PhpGuardCoverageGitIgnoreConfiguratorTest extends ConfigurationUnitTestCas
      */
     private $phpGuardCoverageGitIgnoreConfigurator;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->phpGuardCoverageGitIgnoreConfigurator = new PhpGuardCoverageGitIgnoreConfigurator(
             $this->getQueryBus(),
diff --git a/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/PreCommitProcessorTest.php b/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/PreCommitProcessorTest.php
index 11b8b4c..ae19325 100644
--- a/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/PreCommitProcessorTest.php
+++ b/src/PhpGitHooks/Module/Configuration/Tests/Behaviour/PreCommitProcessorTest.php
@@ -24,7 +24,7 @@ class PreCommitProcessorTest extends ConfigurationUnitTestCase
      */
     private $io;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->io = $this->getIOInterface();
         $this->preCommitProcessor = new PreCommitProcessor(
diff --git a/src/PhpGitHooks/Module/Files/Tests/Behaviour/PhpFilesExtractorQueryHandlerTest.php b/src/PhpGitHooks/Module/Files/Tests/Behaviour/PhpFilesExtractorQueryHandlerTest.php
index fc5f2c4..3807955 100644
--- a/src/PhpGitHooks/Module/Files/Tests/Behaviour/PhpFilesExtractorQueryHandlerTest.php
+++ b/src/PhpGitHooks/Module/Files/Tests/Behaviour/PhpFilesExtractorQueryHandlerTest.php
@@ -15,7 +15,7 @@ class PhpFilesExtractorQueryHandlerTest extends FilesUnitTestCase
      */
     private $phpFilesExtractorQueryHandler;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->phpFilesExtractorQueryHandler = new PhpFilesExtractorHandler();
     }
diff --git a/src/PhpGitHooks/Module/Git/Tests/Behaviour/CommitMsgCommandHandlerTest.php b/src/PhpGitHooks/Module/Git/Tests/Behaviour/CommitMsgCommandHandlerTest.php
index 2a43c57..2ea9df3 100644
--- a/src/PhpGitHooks/Module/Git/Tests/Behaviour/CommitMsgCommandHandlerTest.php
+++ b/src/PhpGitHooks/Module/Git/Tests/Behaviour/CommitMsgCommandHandlerTest.php
@@ -17,7 +17,7 @@ class CommitMsgCommandHandlerTest extends GitUnitTestCase
      */
     private $commitMsgCommandHandler;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->commitMsgCommandHandler = new CommitMsgHandler(
             $this->getMergeValidator(),
diff --git a/src/PhpGitHooks/Module/Git/Tests/Behaviour/GitIgnoreExtractorHandlerTest.php b/src/PhpGitHooks/Module/Git/Tests/Behaviour/GitIgnoreExtractorHandlerTest.php
index 03a5993..49600dd 100644
--- a/src/PhpGitHooks/Module/Git/Tests/Behaviour/GitIgnoreExtractorHandlerTest.php
+++ b/src/PhpGitHooks/Module/Git/Tests/Behaviour/GitIgnoreExtractorHandlerTest.php
@@ -14,7 +14,7 @@ class GitIgnoreExtractorHandlerTest extends GitUnitTestCase
      */
     private $gitIgnoreExtractorQueryHandler;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->gitIgnoreExtractorQueryHandler = new GitIgnoreExtractorHandler($this->getGitIgnoreFileReader());
     }
diff --git a/src/PhpGitHooks/Module/Git/Tests/Behaviour/PreCommitToolHandlerTest.php b/src/PhpGitHooks/Module/Git/Tests/Behaviour/PreCommitToolHandlerTest.php
index e50d876..59bbeb1 100644
--- a/src/PhpGitHooks/Module/Git/Tests/Behaviour/PreCommitToolHandlerTest.php
+++ b/src/PhpGitHooks/Module/Git/Tests/Behaviour/PreCommitToolHandlerTest.php
@@ -30,7 +30,7 @@ class PreCommitToolHandlerTest extends GitUnitTestCase
      */
     private $preCommitToolCommandHandler;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->preCommitToolCommandHandler = new PreCommitToolHandler(
             $this->getOutputInterface(),
diff --git a/src/PhpGitHooks/Module/Git/Tests/Behaviour/PrePushToolHandlerTest.php b/src/PhpGitHooks/Module/Git/Tests/Behaviour/PrePushToolHandlerTest.php
index 2adfabe..b4a6a2f 100644
--- a/src/PhpGitHooks/Module/Git/Tests/Behaviour/PrePushToolHandlerTest.php
+++ b/src/PhpGitHooks/Module/Git/Tests/Behaviour/PrePushToolHandlerTest.php
@@ -23,7 +23,7 @@ class PrePushToolHandlerTest extends GitUnitTestCase
      */
     private $prePushToolCommandHandler;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->prePushToolCommandHandler = new PrePushToolHandler(
             $this->getQueryBus(),
diff --git a/src/PhpGitHooks/Module/JsonLint/Tests/Behaviour/JsonLintToolHandlerTest.php b/src/PhpGitHooks/Module/JsonLint/Tests/Behaviour/JsonLintToolHandlerTest.php
index 3eea0d9..c5b9319 100644
--- a/src/PhpGitHooks/Module/JsonLint/Tests/Behaviour/JsonLintToolHandlerTest.php
+++ b/src/PhpGitHooks/Module/JsonLint/Tests/Behaviour/JsonLintToolHandlerTest.php
@@ -25,7 +25,7 @@ class JsonLintToolHandlerTest extends JsonLintUnitTestCase
      */
     private $errorMessage;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->jsonLintToolCommandHandler = new JsonLintToolHandler(
             new JsonLintToolExecutor(
diff --git a/src/PhpGitHooks/Module/PhpCs/Tests/Behaviour/PhpCsToolHandlerTest.php b/src/PhpGitHooks/Module/PhpCs/Tests/Behaviour/PhpCsToolHandlerTest.php
index 7eb4e5b..12e6b27 100644
--- a/src/PhpGitHooks/Module/PhpCs/Tests/Behaviour/PhpCsToolHandlerTest.php
+++ b/src/PhpGitHooks/Module/PhpCs/Tests/Behaviour/PhpCsToolHandlerTest.php
@@ -18,7 +18,7 @@ class PhpCsToolHandlerTest extends PhpCsUnitTestCase
      */
     private $phpCsToolCommandHandler;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->phpCsToolCommandHandler = new PhpCsToolHandler(
             $this->getOutputInterface(),
diff --git a/src/PhpGitHooks/Module/PhpCsFixer/Tests/Behaviour/PhpCsFixerToolHandlerTest.php b/src/PhpGitHooks/Module/PhpCsFixer/Tests/Behaviour/PhpCsFixerToolHandlerTest.php
index ff8ea5b..683ca52 100644
--- a/src/PhpGitHooks/Module/PhpCsFixer/Tests/Behaviour/PhpCsFixerToolHandlerTest.php
+++ b/src/PhpGitHooks/Module/PhpCsFixer/Tests/Behaviour/PhpCsFixerToolHandlerTest.php
@@ -19,7 +19,7 @@ class PhpCsFixerToolHandlerTest extends PhpCsFixerUnitTestCase
      */
     private $phpCsFixerToolCommandHandler;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->phpCsFixerToolCommandHandler = new PhpCsFixerToolHandler(
             $this->getOutputInterface(),
diff --git a/src/PhpGitHooks/Module/PhpLint/Tests/Behaviour/PhpLintToolHandlerTest.php b/src/PhpGitHooks/Module/PhpLint/Tests/Behaviour/PhpLintToolHandlerTest.php
index d6c89d1..e07e48f 100644
--- a/src/PhpGitHooks/Module/PhpLint/Tests/Behaviour/PhpLintToolHandlerTest.php
+++ b/src/PhpGitHooks/Module/PhpLint/Tests/Behaviour/PhpLintToolHandlerTest.php
@@ -19,7 +19,7 @@ class PhpLintToolHandlerTest extends PhpLintUnitTestCase
      */
     private $phpLintToolCommandHandler;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->phpLintToolCommandHandler = new PhpLintToolHandler(
             $this->getPhpLintToolProcessor(),
diff --git a/src/PhpGitHooks/Module/PhpMd/Tests/Behaviour/PhpMdToolHandlerTest.php b/src/PhpGitHooks/Module/PhpMd/Tests/Behaviour/PhpMdToolHandlerTest.php
index 394d12b..4a1bd7e 100644
--- a/src/PhpGitHooks/Module/PhpMd/Tests/Behaviour/PhpMdToolHandlerTest.php
+++ b/src/PhpGitHooks/Module/PhpMd/Tests/Behaviour/PhpMdToolHandlerTest.php
@@ -19,7 +19,7 @@ class PhpMdToolHandlerTest extends PhpMdUnitTestCase
      */
     private $phpMdToolCommandHandler;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->phpMdToolCommandHandler = new PhpMdToolHandler(
             $this->getOutputInterface(),
diff --git a/src/PhpGitHooks/Module/PhpUnit/Tests/Behaviour/GuardCoverageToolHandlerTest.php b/src/PhpGitHooks/Module/PhpUnit/Tests/Behaviour/GuardCoverageToolHandlerTest.php
index e927e87..0f3e79c 100644
--- a/src/PhpGitHooks/Module/PhpUnit/Tests/Behaviour/GuardCoverageToolHandlerTest.php
+++ b/src/PhpGitHooks/Module/PhpUnit/Tests/Behaviour/GuardCoverageToolHandlerTest.php
@@ -15,7 +15,7 @@ class GuardCoverageToolHandlerTest extends PhpUnitUnitTestCase
      */
     private $guardCoverageToolCommandHandler;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->guardCoverageToolCommandHandler = new GuardCoverageToolHandler(
             $this->getOutputInterface(),
diff --git a/src/PhpGitHooks/Module/PhpUnit/Tests/Behaviour/PhpUnitToolHandlerTest.php b/src/PhpGitHooks/Module/PhpUnit/Tests/Behaviour/PhpUnitToolHandlerTest.php
index 89073d0..ad5ceca 100644
--- a/src/PhpGitHooks/Module/PhpUnit/Tests/Behaviour/PhpUnitToolHandlerTest.php
+++ b/src/PhpGitHooks/Module/PhpUnit/Tests/Behaviour/PhpUnitToolHandlerTest.php
@@ -17,7 +17,7 @@ class PhpUnitToolHandlerTest extends PhpUnitUnitTestCase
      */
     private $phpUnitToolCommandHandler;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->phpUnitToolCommandHandler = new PhpUnitToolHandler(
             $this->getOutputInterface(),
diff --git a/src/PhpGitHooks/Module/PhpUnit/Tests/Behaviour/StrictCoverageToolHandlerTest.php b/src/PhpGitHooks/Module/PhpUnit/Tests/Behaviour/StrictCoverageToolHandlerTest.php
index 7f7f9ab..db03898 100644
--- a/src/PhpGitHooks/Module/PhpUnit/Tests/Behaviour/StrictCoverageToolHandlerTest.php
+++ b/src/PhpGitHooks/Module/PhpUnit/Tests/Behaviour/StrictCoverageToolHandlerTest.php
@@ -23,7 +23,7 @@ class StrictCoverageToolHandlerTest extends PhpUnitUnitTestCase
      */
     private $strictCoverageToolCommandHandler;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->errorMessage = ConfigArrayDataStub::ERROR_MESSAGE;
         $this->strictCoverageToolCommandHandler = new StrictCoverageToolHandler(