diff --git a/.github/workflows/code_checks.yaml b/.github/workflows/code_checks.yaml
index fd369b2f..f8f3a0ab 100644
--- a/.github/workflows/code_checks.yaml
+++ b/.github/workflows/code_checks.yaml
@@ -1,7 +1,7 @@
 name: Code_Checks
 
 on:
-    pull_request: null
+    pull_request:
     push:
         branches:
             - master
@@ -11,36 +11,64 @@ jobs:
         runs-on: ubuntu-latest
         strategy:
             matrix:
-                php: ['7.2', '7.3', '7.4']
+                php:
+                    - "7.2"
+                    - "7.3"
+                    - "7.4"
+                symfony:
+                    - 3.*
+                    - 4.*
+                    - 5.*
+                dependency-version:
+                    # - prefer-lowest
+                    - prefer-stable
 
-        name: PHP ${{ matrix.php }} tests
+        name: PHP ${{ matrix.php }} - S ${{ matrix.symfony }} - ${{ matrix.dependency-version }} - tests
         steps:
             # basically git clone
-            -   uses: actions/checkout@v2
+            - uses: actions/checkout@v2
 
-            # use PHP of specific version
-            -   uses: shivammathur/setup-php@v1
-                with:
-                    php-version: ${{ matrix.php }}
-                    coverage: none # disable xdebug, pcov
-            
-            -   run: git --version
-            -   run: git config --global user.email "test@github.com"
-            -   run: git config --global user.name "GitHub Action"
-            -   run: git --version
+            - name: Setup Git
+              run: |
+                  git --version
+                  git config --global user.email "test@github.com"
+                  git config --global user.name "GitHub Action"
+                  git --version
 
-            # if we 2 steps like this, we can better see if composer failed or tests
-            -   run: composer install --no-progress
+            - name: Setup PHP
+              # use PHP of specific version
+              uses: shivammathur/setup-php@v1
+              with:
+                  php-version: ${{ matrix.php }}
+                  coverage: none # disable xdebug, pcov
+                  tools: composer
 
-            -   run: composer tests
+            - name: Install Composer Dependencies
+              run: |
+                  composer require "symfony/process:${{ matrix.symfony }}" "symfony/filesystem:${{ matrix.symfony }}" "symfony/finder:${{ matrix.symfony }}" --no-interaction --no-update
+                  composer update --${{ matrix.dependency-version }} --prefer-dist --no-interaction --no-suggest
+
+            - name: Run PHPUnit Tests
+              run: composer tests
+
+    static_tests:
+        runs-on: ubuntu-latest
+        steps:
+            - uses: actions/checkout@v2
+            - uses: shivammathur/setup-php@v1
+              with:
+                  php-version: 7.3
+                  coverage: none # disable xdebug, pcov
+            - run: composer install --no-progress
+            - run: ./vendor/bin/phpstan analyse -c phpstan.neon
 
     code_style:
         runs-on: ubuntu-latest
         steps:
-            -   uses: actions/checkout@v2
-            -   uses: shivammathur/setup-php@v1
-                with:
-                    php-version: 7.3
-                    coverage: none # disable xdebug, pcov
-            -   run: composer install --no-progress
-            -   run: composer check-cs
+            - uses: actions/checkout@v2
+            - uses: shivammathur/setup-php@v1
+              with:
+                  php-version: 7.3
+                  coverage: none # disable xdebug, pcov
+            - run: composer install --no-progress
+            - run: composer check-cs
diff --git a/README.md b/README.md
index 249aa8a0..5e18ae05 100644
--- a/README.md
+++ b/README.md
@@ -1,8 +1,16 @@
 ![GitElephant](https://raw.github.com/matteosister/GitElephant/develop/graphics/gitelephant_600.png)
 
-[![Latest Stable Version](https://poser.pugx.org/cypresslab/GitElephant/v/stable.png)](https://packagist.org/packages/cypresslab/GitElephant) [![License](https://poser.pugx.org/cypresslab/gitelephant/license.png)](https://packagist.org/packages/cypresslab/gitelephant) [![Total Downloads](https://poser.pugx.org/cypresslab/GitElephant/downloads.png)](https://packagist.org/packages/cypresslab/GitElephant) [![Montly Downloads](https://poser.pugx.org/cypresslab/gitelephant/d/monthly.png)](https://packagist.org/packages/cypresslab/gitelephant)
-
-[![Build Status](https://travis-ci.org/matteosister/GitElephant.png?branch=master)](https://travis-ci.org/matteosister/GitElephant) [![Dependency Status](https://www.versioneye.com/user/projects/53da38094b3ac86052000019/badge.svg?style=flat)](https://www.versioneye.com/user/projects/53da38094b3ac86052000019) [![Scrutinizer Quality Score](https://scrutinizer-ci.com/g/matteosister/GitElephant/badges/quality-score.png?s=c7ca8a7c5ea9c64b291f6bcaef27955ed6d8a836)](https://scrutinizer-ci.com/g/matteosister/GitElephant/) [![Code Coverage](https://scrutinizer-ci.com/g/matteosister/GitElephant/badges/coverage.png?s=fd7981a4f57fd639912d1a415e3dd92615ddce51)](https://scrutinizer-ci.com/g/matteosister/GitElephant/) [![SensioLabsInsight](https://insight.sensiolabs.com/projects/d6da541e-d928-4f70-868a-dd0b6426a7b5/mini.png)](https://insight.sensiolabs.com/projects/d6da541e-d928-4f70-868a-dd0b6426a7b5)
+[![Latest Stable Version](https://poser.pugx.org/cypresslab/GitElephant/v/stable.png)](https://packagist.org/packages/cypresslab/GitElephant) 
+[![License](https://poser.pugx.org/cypresslab/gitelephant/license.png)](https://packagist.org/packages/cypresslab/gitelephant) 
+[![Total Downloads](https://poser.pugx.org/cypresslab/GitElephant/downloads.png)](https://packagist.org/packages/cypresslab/GitElephant) 
+[![Montly Downloads](https://poser.pugx.org/cypresslab/gitelephant/d/monthly.png)](https://packagist.org/packages/cypresslab/gitelephant)
+
+[![Build Status](https://travis-ci.org/matteosister/GitElephant.png?branch=master)](https://travis-ci.org/matteosister/GitElephant) 
+[![Code Check](https://github.com/matteosister/GitElephant/workflows/.github/workflows/code_checks.yaml/badge.svg)](.github/workflows/code_checks.yaml)
+[![Dependency Status](https://www.versioneye.com/user/projects/53da38094b3ac86052000019/badge.svg?style=flat)](https://www.versioneye.com/user/projects/53da38094b3ac86052000019) 
+[![Scrutinizer Quality Score](https://scrutinizer-ci.com/g/matteosister/GitElephant/badges/quality-score.png?s=c7ca8a7c5ea9c64b291f6bcaef27955ed6d8a836)](https://scrutinizer-ci.com/g/matteosister/GitElephant/) 
+[![Code Coverage](https://scrutinizer-ci.com/g/matteosister/GitElephant/badges/coverage.png?s=fd7981a4f57fd639912d1a415e3dd92615ddce51)](https://scrutinizer-ci.com/g/matteosister/GitElephant/) 
+[![SensioLabsInsight](https://insight.sensiolabs.com/projects/d6da541e-d928-4f70-868a-dd0b6426a7b5/mini.png)](https://insight.sensiolabs.com/projects/d6da541e-d928-4f70-868a-dd0b6426a7b5)
 
 GitElephant is an abstraction layer to manage your git repositories with php
 
diff --git a/composer.json b/composer.json
index 4dda76c6..4441f677 100644
--- a/composer.json
+++ b/composer.json
@@ -19,18 +19,19 @@
     ],
     "require": {
         "php": ">=7.2.0",
-        "symfony/process": "~2.8|~3.0|~4.0|~5.0",
-        "symfony/filesystem": "~2.8|~3.0|~4.0|~5.0",
-        "symfony/finder": "~2.8|~3.0|~4.0|~5.0",
-        "phpcollection/phpcollection": "~0.4|~5.0"
+        "symfony/process": "~3.4|~4.0|~5.0",
+        "symfony/filesystem": "~3.4|~4.0|~5.0",
+        "symfony/finder": "~3.4|~4.0|~5.0",
+        "phpcollection/phpcollection": "~0.4|~0.5"
     },
     "require-dev": {
         "php": ">=7.2.0",
         "phpunit/phpunit": "~8.0|~9.0",
         "mockery/mockery": "~1.1",
-        "symfony/var-dumper": "~3.0|~4.0|~5.0",
-        "rector/rector": "^0.7.6",
-        "symplify/easy-coding-standard": "^v7.2.5"
+        "rector/rector": "*",
+        "symplify/easy-coding-standard": "*",
+        "phpstan/phpstan": "*",
+        "phpstan/phpstan-phpunit": "*"
     },
     "minimum-stability": "stable",
     "autoload": {
diff --git a/phpstan.neon b/phpstan.neon
new file mode 100644
index 00000000..2a2058c1
--- /dev/null
+++ b/phpstan.neon
@@ -0,0 +1,20 @@
+parameters:
+	level: 6
+	paths:
+		- src
+		# - tests
+	
+	# things we disable for the moement, but one day...
+	inferPrivatePropertyTypeFromConstructor: true
+	checkMissingIterableValueType: false
+	checkGenericClassInNonGenericObjectType: false
+	ignoreErrors:
+		- 
+			message: '#Unsafe usage of new static\(\).#'
+			path: %currentWorkingDirectory%
+		-
+			message: '#Parameter \#1 \$command of class Symfony\\Component\\Process\\Process constructor expects array, string given.#'
+			path: src/GitElephant/Command/Caller/Caller.php
+
+includes:
+    - vendor/phpstan/phpstan-phpunit/extension.neon
diff --git a/src/GitElephant/Command/BaseCommand.php b/src/GitElephant/Command/BaseCommand.php
index 321558ce..9486beaa 100644
--- a/src/GitElephant/Command/BaseCommand.php
+++ b/src/GitElephant/Command/BaseCommand.php
@@ -35,7 +35,7 @@ class BaseCommand
     /**
      * the command name
      *
-     * @var string
+     * @var string|null
      */
     private $commandName = null;
 
@@ -77,31 +77,31 @@ class BaseCommand
     /**
      * the command subject
      *
-     * @var string|SubCommandCommand
+     * @var string|SubCommandCommand|null
      */
     private $commandSubject = null;
 
     /**
      * the command second subject (i.e. for branch)
      *
-     * @var string|SubCommandCommand
+     * @var string|SubCommandCommand|null
      */
     private $commandSubject2 = null;
 
     /**
      * the path
      *
-     * @var string
+     * @var string|null
      */
     private $path = null;
 
     /**
-     * @var string
+     * @var string|null
      */
     private $binaryVersion;
 
     /**
-     * @var Repository
+     * @var Repository|null
      */
     private $repo;
 
@@ -143,6 +143,12 @@ public function clearAll(): void
         $this->binaryVersion = null;
     }
 
+    /**
+     * Get a new instance of this command
+     *
+     * @param Repository $repo
+     * @return static
+     */
     public static function getInstance(Repository $repo = null)
     {
         return new static($repo);
@@ -153,7 +159,7 @@ public static function getInstance(Repository $repo = null)
      *
      * @param string $commandName the command name
      */
-    protected function addCommandName($commandName): void
+    protected function addCommandName(string $commandName): void
     {
         $this->commandName = $commandName;
     }
@@ -456,9 +462,11 @@ private function getCLISubjects(): string
     }
 
     /**
+     * Get the version of the git binary
+     *
      * @return string|null
      */
-    public function getBinaryVersion(): string
+    public function getBinaryVersion(): ?string
     {
         if (is_null($this->binaryVersion)) {
             $this->binaryVersion = $this->repo->getCaller()->getBinaryVersion();
diff --git a/src/GitElephant/Command/Caller/AbstractCaller.php b/src/GitElephant/Command/Caller/AbstractCaller.php
index 2e15b238..1a5b3ff7 100644
--- a/src/GitElephant/Command/Caller/AbstractCaller.php
+++ b/src/GitElephant/Command/Caller/AbstractCaller.php
@@ -30,14 +30,14 @@ abstract class AbstractCaller implements CallerInterface
     /**
      * Git binary path
      *
-     * @var string
+     * @var string|null
      */
     protected $binaryPath;
 
     /**
      * Git binary version
      *
-     * @var string
+     * @var string|null
      */
     protected $binaryVersion;
 
@@ -48,6 +48,13 @@ abstract class AbstractCaller implements CallerInterface
      */
     protected $outputLines = [];
 
+    /**
+     * raw output of the command
+     *
+     * @var string
+     */
+    protected $rawOutput;
+
     /**
      * @inheritdoc
      */
@@ -117,4 +124,14 @@ public function getOutputLines(bool $stripBlankLines = false): array
 
         return $this->outputLines;
     }
+
+    /**
+     * Get RawOutput
+     *
+     * @return string
+     */
+    public function getRawOutput(): string
+    {
+        return $this->rawOutput;
+    }
 }
diff --git a/src/GitElephant/Command/Caller/Caller.php b/src/GitElephant/Command/Caller/Caller.php
index d124f48b..41a8e94f 100644
--- a/src/GitElephant/Command/Caller/Caller.php
+++ b/src/GitElephant/Command/Caller/Caller.php
@@ -38,13 +38,6 @@ class Caller extends AbstractCaller
      */
     private $repositoryPath;
 
-    /**
-     * raw output
-     *
-     * @var string
-     */
-    private $rawOutput;
-
     /**
      * Class constructor
      *
diff --git a/src/GitElephant/Command/Caller/CallerInterface.php b/src/GitElephant/Command/Caller/CallerInterface.php
index 5a9da4d2..2f1f8d3a 100644
--- a/src/GitElephant/Command/Caller/CallerInterface.php
+++ b/src/GitElephant/Command/Caller/CallerInterface.php
@@ -34,17 +34,37 @@ interface CallerInterface
      *
      * @return CallerInterface
      */
-    public function execute(string $cmd, bool $git = true, string $cwd = null): CallerInterface;
+    public function execute(
+        string $cmd,
+        bool $git = true,
+        string $cwd = null
+    ): CallerInterface;
 
     /**
      * after calling execute this method should return the output
      *
      * @param bool $stripBlankLines strips the blank lines
      *
-     * @return array
+     * @return array<string>
      */
     public function getOutputLines(bool $stripBlankLines = false): array;
 
+    /**
+     * Returns the output of the last executed command.
+     * May be adjusted, such as trimmed.
+     *
+     * @return string
+     */
+    public function getOutput(): string;
+
+    /**
+     * Returns the output of the last executed command.
+     * May not be adjusted, not trimmed or anything, really raw.
+     *
+     * @return string
+     */
+    public function getRawOutput(): string;
+
     /**
      * Get the binary path
      *
diff --git a/src/GitElephant/Command/Caller/CallerSSH2.php b/src/GitElephant/Command/Caller/CallerSSH2.php
index 0a3478a9..a9df906d 100644
--- a/src/GitElephant/Command/Caller/CallerSSH2.php
+++ b/src/GitElephant/Command/Caller/CallerSSH2.php
@@ -55,17 +55,22 @@ public function __construct($resource, $gitPath = '/usr/bin/git')
      *
      * @return CallerInterface
      */
-    public function execute($cmd, $git = true, $cwd = null): \GitElephant\Command\Caller\CallerInterface
-    {
+    public function execute(
+        $cmd,
+        $git = true,
+        $cwd = null
+    ): \GitElephant\Command\Caller\CallerInterface {
         if ($git) {
             $cmd = $this->getBinaryPath() . ' ' . $cmd;
         }
         $stream = ssh2_exec($this->resource, $cmd);
-        stream_set_blocking($stream, 1);
+        stream_set_blocking($stream, true);
         $data = stream_get_contents($stream);
         fclose($stream);
+        
+        $this->rawOutput = $data === false ? '' : $data;
         // rtrim values
-        $values = array_map('rtrim', explode(PHP_EOL, $data));
+        $values = array_map('rtrim', explode(PHP_EOL, $this->rawOutput));
         $this->outputLines = $values;
 
         return $this;
diff --git a/src/GitElephant/Command/DiffCommand.php b/src/GitElephant/Command/DiffCommand.php
index c33560cb..542c00dd 100644
--- a/src/GitElephant/Command/DiffCommand.php
+++ b/src/GitElephant/Command/DiffCommand.php
@@ -48,7 +48,7 @@ public function __construct(Repository $repo = null)
      *
      * @param TreeishInterface      $of   the reference to diff
      * @param TreeishInterface|null $with the source reference to diff with $of, if not specified is the current HEAD
-     * @param null                  $path the path to diff, if not specified the full repository
+     * @param string|null                 $path the path to diff, if not specified the full repository
      *
      * @throws \RuntimeException
      * @return string
@@ -83,7 +83,7 @@ public function diff($of, $with = null, $path = null): string
             }
             $this->addPath($path);
         }
-        
+
         $this->addCommandSubject($subject);
 
         return $this->getCommand();
diff --git a/src/GitElephant/Command/LsTreeCommand.php b/src/GitElephant/Command/LsTreeCommand.php
index 47e964ee..9e5d75a2 100644
--- a/src/GitElephant/Command/LsTreeCommand.php
+++ b/src/GitElephant/Command/LsTreeCommand.php
@@ -74,7 +74,7 @@ public function fullTree($ref = 'HEAD'): string
     /**
      * tree of a given path
      *
-     * @param string            $ref  reference
+     * @param string|TreeishInterface        $ref  reference
      * @param string|NodeObject $path path
      *
      * @throws \RuntimeException
diff --git a/src/GitElephant/Command/MainCommand.php b/src/GitElephant/Command/MainCommand.php
index b047fa78..b0d00bad 100644
--- a/src/GitElephant/Command/MainCommand.php
+++ b/src/GitElephant/Command/MainCommand.php
@@ -58,7 +58,7 @@ public function __construct(Repository $repo = null)
      * @param bool $bare
      *
      * @throws \RuntimeException
-     * @return MainCommand
+     * @return string
      */
     public function init($bare = false): string
     {
@@ -131,15 +131,16 @@ public function unstage($what): string
     /**
      * Commit
      *
-     * @param string        $message  the commit message
+     * @param string|null        $message  the commit message
      * @param bool          $stageAll commit all changes
      * @param string|Author $author   override the author for this commit
+     * @param bool $allowEmpty whether to add param `--allow-empty` to commit command
      *
      * @throws \RuntimeException
      * @throws \InvalidArgumentException
      * @return string
      */
-    public function commit($message, $stageAll = false, $author = null, $allowEmpty = false): string
+    public function commit(?string $message, bool $stageAll = false, $author = null, bool $allowEmpty = false): string
     {
         $this->clearAll();
 
@@ -170,7 +171,7 @@ public function commit($message, $stageAll = false, $author = null, $allowEmpty
     /**
      * Checkout a treeish reference
      *
-     * @param string|Branch $ref the reference to checkout
+     * @param string|Branch|TreeishInterface $ref the reference to checkout
      *
      * @throws \RuntimeException
      * @return string
@@ -238,7 +239,7 @@ public function move($from, $to): string
     public function remove($path, $recursive, $force): string
     {
         $this->clearAll();
-        
+
         $path = trim($path);
         if (!$this->validatePath($path)) {
             throw new \InvalidArgumentException('Invalid path');
@@ -253,7 +254,7 @@ public function remove($path, $recursive, $force): string
         if ($force) {
             $this->addCommandArgument('-f');
         }
-        
+
         $this->addPath($path);
 
         return $this->getCommand();
diff --git a/src/GitElephant/Command/Remote/AddSubCommand.php b/src/GitElephant/Command/Remote/AddSubCommand.php
index 5a3ba205..46acd586 100644
--- a/src/GitElephant/Command/Remote/AddSubCommand.php
+++ b/src/GitElephant/Command/Remote/AddSubCommand.php
@@ -88,7 +88,7 @@ public function addCmdSwitchOptions(): array
      * @param string $url     URL of remote
      * @param array  $options options for the add subcommand
      *
-     * @return string
+     * @return AddSubCommand
      */
     public function prepare($name, $url, $options = []): self
     {
diff --git a/src/GitElephant/Command/ResetCommand.php b/src/GitElephant/Command/ResetCommand.php
index b71c8ff7..b973ea8d 100644
--- a/src/GitElephant/Command/ResetCommand.php
+++ b/src/GitElephant/Command/ResetCommand.php
@@ -44,11 +44,10 @@ public function reset($arg = null, array $options = []): string
         $this->clearAll();
         $this->addCommandName(self::GIT_RESET_COMMAND);
         // if there are options add them.
-        if (!is_null($options)) {
-            foreach ($options as $option) {
-                $this->addCommandArgument($option);
-            }
+        foreach ($options as $option) {
+            $this->addCommandArgument($option);
         }
+
         if ($arg != null) {
             $this->addCommandSubject2($arg);
         }
diff --git a/src/GitElephant/Command/RevParseCommand.php b/src/GitElephant/Command/RevParseCommand.php
index e2ee96f8..8e84e665 100644
--- a/src/GitElephant/Command/RevParseCommand.php
+++ b/src/GitElephant/Command/RevParseCommand.php
@@ -91,11 +91,10 @@ public function revParse($arg = null, array $options = []): string
         $this->clearAll();
         $this->addCommandName(self::GIT_REV_PARSE_COMMAND);
         // if there are options add them.
-        if (!is_null($options)) {
-            foreach ($options as $option) {
-                $this->addCommandArgument($option);
-            }
+        foreach ($options as $option) {
+            $this->addCommandArgument($option);
         }
+
         if (!is_null($arg)) {
             $this->addCommandSubject2($arg);
         }
diff --git a/src/GitElephant/Command/StashCommand.php b/src/GitElephant/Command/StashCommand.php
index 571fe22a..058760ac 100644
--- a/src/GitElephant/Command/StashCommand.php
+++ b/src/GitElephant/Command/StashCommand.php
@@ -96,7 +96,7 @@ public function listStashes(array $options = null): string
     /**
      * Shows details for a specific stash
      *
-     * @param string $stash
+     * @param string|int $stash
      *
      * @return string
      */
@@ -212,7 +212,7 @@ public function create(): string
     }
 
     /**
-     * @param $stash
+     * @param int|string $stash
      *
      * @return string
      */
diff --git a/src/GitElephant/Command/SubCommandCommand.php b/src/GitElephant/Command/SubCommandCommand.php
index 9ad4c336..a1443e26 100644
--- a/src/GitElephant/Command/SubCommandCommand.php
+++ b/src/GitElephant/Command/SubCommandCommand.php
@@ -35,6 +35,8 @@ class SubCommandCommand extends BaseCommand
 {
     /**
      * Subjects to a subcommand name
+     *
+     * @var array<SubCommandCommand|array|string>
      */
     private $orderedSubjects = [];
 
@@ -55,9 +57,15 @@ public function __construct(Repository $repo = null)
     public function clearAll(): void
     {
         parent::clearAll();
-        $this->orderedSubjects = null;
+        $this->orderedSubjects = [];
     }
 
+    /**
+     * Add a subject to this subcommand
+     *
+     * @param SubCommandCommand|array|string $subject
+     * @return void
+     */
     protected function addCommandSubject($subject): void
     {
         $this->orderedSubjects[] = $subject;
@@ -65,10 +73,10 @@ protected function addCommandSubject($subject): void
 
     protected function getCommandSubjects(): array
     {
-        return is_array($this->orderedSubjects) ? $this->orderedSubjects : [];
+        return $this->orderedSubjects;
     }
 
-    protected function extractArguments($args): string
+    protected function extractArguments(array $args): string
     {
         $orderArgs = [];
         foreach ($args as $arg) {
@@ -96,10 +104,6 @@ public function getCommand(): string
     {
         $command = $this->getCommandName();
 
-        if (is_null($command)) {
-            throw new \RuntimeException("commandName must be specified to build a subcommand");
-        }
-
         $command .= ' ';
         $args = $this->getCommandArguments();
         if (count($args) > 0) {
diff --git a/src/GitElephant/Command/TagCommand.php b/src/GitElephant/Command/TagCommand.php
index eb72485a..b4c58a83 100644
--- a/src/GitElephant/Command/TagCommand.php
+++ b/src/GitElephant/Command/TagCommand.php
@@ -48,7 +48,7 @@ public function __construct(Repository $repo = null)
      *
      * @param string      $name       The new tag name
      * @param string|null $startPoint the new tag start point.
-     * @param null        $message    the tag message
+     * @param string|null       $message    the tag message
      *
      * @throws \RuntimeException
      * @return string the command
diff --git a/src/GitElephant/Exception/InvalidBranchNameException.php b/src/GitElephant/Exception/InvalidBranchNameException.php
index eec59ec6..9c5ea8ce 100644
--- a/src/GitElephant/Exception/InvalidBranchNameException.php
+++ b/src/GitElephant/Exception/InvalidBranchNameException.php
@@ -27,5 +27,10 @@
  */
 class InvalidBranchNameException extends \InvalidArgumentException
 {
+    /**
+     * The message of the exception
+     *
+     * @var string
+     */
     protected $message = 'The name provided is not a valid branch name';
 }
diff --git a/src/GitElephant/Exception/InvalidRepositoryPathException.php b/src/GitElephant/Exception/InvalidRepositoryPathException.php
index dced9ae3..11ade45c 100644
--- a/src/GitElephant/Exception/InvalidRepositoryPathException.php
+++ b/src/GitElephant/Exception/InvalidRepositoryPathException.php
@@ -27,6 +27,11 @@
  */
 class InvalidRepositoryPathException extends \InvalidArgumentException
 {
+    /**
+     * The exception message template
+     *
+     * @var string
+     */
     protected $messageTpl = 'The path provided (%s) is not a valid git repository path';
 
     /**
diff --git a/src/GitElephant/Objects/Author.php b/src/GitElephant/Objects/Author.php
index aafff67c..e694a7d3 100644
--- a/src/GitElephant/Objects/Author.php
+++ b/src/GitElephant/Objects/Author.php
@@ -64,9 +64,9 @@ public function setEmail(string $email): void
     /**
      * email getter
      *
-     * @return string
+     * @return string|null
      */
-    public function getEmail(): string
+    public function getEmail(): ?string
     {
         return $this->email;
     }
@@ -84,9 +84,9 @@ public function setName(string $name): void
     /**
      * name getter
      *
-     * @return mixed
+     * @return string|null
      */
-    public function getName(): string
+    public function getName(): ?string
     {
         return $this->name;
     }
diff --git a/src/GitElephant/Objects/Branch.php b/src/GitElephant/Objects/Branch.php
index 43b39ada..cc347aed 100644
--- a/src/GitElephant/Objects/Branch.php
+++ b/src/GitElephant/Objects/Branch.php
@@ -84,9 +84,12 @@ public static function create(
         string $name,
         string $startPoint = null
     ): \GitElephant\Objects\Branch {
+        /** @var BranchCommand */
+        $branchCommand = BranchCommand::getInstance($repository);
+
         $repository
             ->getCaller()
-            ->execute(BranchCommand::getInstance($repository)->create($name, $startPoint));
+            ->execute($branchCommand->create($name, $startPoint));
 
         return new self($repository, $name);
     }
@@ -151,7 +154,7 @@ public function __construct(Repository $repository, string $name)
      *
      * @throws \InvalidArgumentException
      */
-    private function createFromCommand()
+    private function createFromCommand(): void
     {
         $command = BranchCommand::getInstance($this->getRepository())->listBranches();
         $outputLines = $this->repository->getCaller()->execute($command)->getOutputLines(true);
@@ -210,7 +213,7 @@ public static function getMatches(string $branchString): array
         while (empty($matches) and $regex = array_pop($regexList)) {
             preg_match($regex, trim($branchString), $matches);
         }
-        
+
         if (empty($matches)) {
             throw new \InvalidArgumentException(sprintf('the branch string is not valid: %s', $branchString));
         }
diff --git a/src/GitElephant/Objects/Diff/Diff.php b/src/GitElephant/Objects/Diff/Diff.php
index e5d1a094..f57e0af3 100644
--- a/src/GitElephant/Objects/Diff/Diff.php
+++ b/src/GitElephant/Objects/Diff/Diff.php
@@ -20,6 +20,7 @@
 
 namespace GitElephant\Objects\Diff;
 
+use GitElephant\Command\Caller\CallerInterface;
 use GitElephant\Command\DiffCommand;
 use GitElephant\Command\DiffTreeCommand;
 use GitElephant\Repository;
@@ -47,7 +48,7 @@ class Diff implements \ArrayAccess, \Countable, \Iterator
     /**
      * DiffObject instances
      *
-     * @var array
+     * @var array<DiffObject>
      */
     private $diffObjects = [];
 
@@ -81,7 +82,7 @@ public static function create(
      * bare Diff object
      *
      * @param \GitElephant\Repository $repository  repository instance
-     * @param null                    $diffObjects diff objects
+     * @param array<DiffObject>                  $diffObjects  array of diff objects
      */
     public function __construct(Repository $repository, array $diffObjects = [])
     {
@@ -93,9 +94,9 @@ public function __construct(Repository $repository, array $diffObjects = [])
     /**
      * get the commit properties from command
      *
-     * @param null $commit1 commit 1
-     * @param null $commit2 commit 2
-     * @param null $path    path
+     * @param string|null$commit1 commit 1
+     * @param string|null$commit2 commit 2
+     * @param string|null$path    path
      *
      * @throws \RuntimeException
      * @throws \Symfony\Component\Process\Exception\InvalidArgumentException
@@ -126,7 +127,7 @@ public function createFromCommand($commit1 = null, $commit2 = null, $path = null
             }
             $command = DiffCommand::getInstance($this->repository)->diff($commit1, $commit2, $path);
         }
-        
+
         $outputLines = $this->getCaller()->execute($command)->getOutputLines();
         $this->parseOutputLines($outputLines);
     }
@@ -149,9 +150,9 @@ private function parseOutputLines(array $outputLines): void
     }
 
     /**
-     * @return \GitElephant\Command\Caller\Caller
+     * @return \GitElephant\Command\Caller\CallerInterface
      */
-    private function getCaller(): \GitElephant\Command\Caller\Caller
+    private function getCaller(): CallerInterface
     {
         return $this->getRepository()->getCaller();
     }
@@ -203,7 +204,7 @@ public function offsetGet($offset)
     /**
      * ArrayAccess interface
      *
-     * @param int   $offset offset
+     * @param int|null   $offset offset
      * @param mixed $value  value
      */
     public function offsetSet($offset, $value): void
diff --git a/src/GitElephant/Objects/Diff/DiffChunk.php b/src/GitElephant/Objects/Diff/DiffChunk.php
index 3ccfa4b9..39706d3a 100644
--- a/src/GitElephant/Objects/Diff/DiffChunk.php
+++ b/src/GitElephant/Objects/Diff/DiffChunk.php
@@ -72,7 +72,7 @@ class DiffChunk implements \ArrayAccess, \Countable, \Iterator
     /**
      * array of lines
      *
-     * @var array
+     * @var array<DiffChunkLine>
      */
     private $lines = [];
 
@@ -86,7 +86,7 @@ class DiffChunk implements \ArrayAccess, \Countable, \Iterator
     public function __construct(array $lines)
     {
         $this->position = 0;
-        
+
         $this->getLinesNumbers($lines[0]);
         $this->parseLines(array_slice($lines, 1));
     }
@@ -98,7 +98,7 @@ public function __construct(array $lines)
      *
      * @throws \Exception
      */
-    private function parseLines(array $lines)
+    private function parseLines(array $lines): void
     {
         $originUnchanged = $this->originStartLine;
         $destUnchanged = $this->destStartLine;
@@ -234,7 +234,7 @@ public function offsetExists($offset): bool
      *
      * @param int $offset offset
      *
-     * @return null
+     * @return DiffChunkLine|null
      */
     public function offsetGet($offset)
     {
@@ -244,7 +244,7 @@ public function offsetGet($offset)
     /**
      * ArrayAccess interface
      *
-     * @param int   $offset offset
+     * @param int|null   $offset offset
      * @param mixed $value  value
      */
     public function offsetSet($offset, $value): void
@@ -269,7 +269,7 @@ public function offsetUnset($offset): void
     /**
      * Countable interface
      *
-     * @return int|void
+     * @return int
      */
     public function count(): int
     {
diff --git a/src/GitElephant/Objects/Diff/DiffChunkLine.php b/src/GitElephant/Objects/Diff/DiffChunkLine.php
index 97bd11a0..49c15007 100644
--- a/src/GitElephant/Objects/Diff/DiffChunkLine.php
+++ b/src/GitElephant/Objects/Diff/DiffChunkLine.php
@@ -68,7 +68,7 @@ public function setType(string $type): void
     /**
      * type getter
      *
-     * @return mixed
+     * @return string
      */
     public function getType(): string
     {
@@ -88,7 +88,7 @@ public function setContent(string $content): void
     /**
      * content getter
      *
-     * @return mixed
+     * @return string
      */
     public function getContent(): string
     {
diff --git a/src/GitElephant/Objects/Diff/DiffChunkLineAdded.php b/src/GitElephant/Objects/Diff/DiffChunkLineAdded.php
index 5790c1fa..bf08ff54 100644
--- a/src/GitElephant/Objects/Diff/DiffChunkLineAdded.php
+++ b/src/GitElephant/Objects/Diff/DiffChunkLineAdded.php
@@ -45,8 +45,8 @@ public function __construct(int $number, string $content)
      *
      * @return int
      */
-    public function getOriginNumber(): int
+    public function getOriginNumber(): ?int
     {
-        return '';
+        return null;
     }
 }
diff --git a/src/GitElephant/Objects/Diff/DiffChunkLineChanged.php b/src/GitElephant/Objects/Diff/DiffChunkLineChanged.php
index 2178d28f..6dbd4e5f 100644
--- a/src/GitElephant/Objects/Diff/DiffChunkLineChanged.php
+++ b/src/GitElephant/Objects/Diff/DiffChunkLineChanged.php
@@ -49,7 +49,7 @@ public function setNumber(int $number): void
      *
      * @return int
      */
-    public function getNumber(): int
+    public function getNumber(): ?int
     {
         return $this->number;
     }
@@ -59,7 +59,7 @@ public function getNumber(): int
      *
      * @return int
      */
-    public function getOriginNumber(): int
+    public function getOriginNumber(): ?int
     {
         return $this->getNumber();
     }
@@ -69,7 +69,7 @@ public function getOriginNumber(): int
      *
      * @return int
      */
-    public function getDestNumber(): int
+    public function getDestNumber(): ?int
     {
         return $this->getNumber();
     }
diff --git a/src/GitElephant/Objects/Diff/DiffChunkLineDeleted.php b/src/GitElephant/Objects/Diff/DiffChunkLineDeleted.php
index a753f45c..ff97dd36 100644
--- a/src/GitElephant/Objects/Diff/DiffChunkLineDeleted.php
+++ b/src/GitElephant/Objects/Diff/DiffChunkLineDeleted.php
@@ -45,8 +45,8 @@ public function __construct(int $number, string $content)
      *
      * @return int
      */
-    public function getDestNumber(): int
+    public function getDestNumber(): ?int
     {
-        return '';
+        return null;
     }
 }
diff --git a/src/GitElephant/Objects/Diff/DiffChunkLineUnchanged.php b/src/GitElephant/Objects/Diff/DiffChunkLineUnchanged.php
index 3cb5450c..c446e7ca 100644
--- a/src/GitElephant/Objects/Diff/DiffChunkLineUnchanged.php
+++ b/src/GitElephant/Objects/Diff/DiffChunkLineUnchanged.php
@@ -73,7 +73,7 @@ public function setOriginNumber(int $number): void
      *
      * @return int
      */
-    public function getOriginNumber(): int
+    public function getOriginNumber(): ?int
     {
         return $this->originNumber;
     }
@@ -93,7 +93,7 @@ public function setDestNumber(int $number): void
      *
      * @return int
      */
-    public function getDestNumber(): int
+    public function getDestNumber(): ?int
     {
         return $this->destNumber;
     }
diff --git a/src/GitElephant/Objects/Diff/DiffObject.php b/src/GitElephant/Objects/Diff/DiffObject.php
index 9616ad8d..55cb394c 100644
--- a/src/GitElephant/Objects/Diff/DiffObject.php
+++ b/src/GitElephant/Objects/Diff/DiffObject.php
@@ -38,35 +38,35 @@ class DiffObject implements \ArrayAccess, \Countable, \Iterator
     /**
      * the cursor position
      *
-     * @var int
+     * @var int|null
      */
     private $position;
 
     /**
      * the original file path for the diff object
      *
-     * @var string
+     * @var string|null
      */
     private $originalPath;
 
     /**
      * the destination path for the diff object
      *
-     * @var string
+     * @var string|null
      */
     private $destinationPath;
 
     /**
      * rename similarity index
      *
-     * @var int
+     * @var int|null
      */
     private $similarityIndex;
 
     /**
      * the diff mode
      *
-     * @var string
+     * @var string|null
      */
     private $mode;
 
@@ -116,9 +116,9 @@ public function __construct(array $lines)
     /**
      * toString magic method
      *
-     * @return mixed
+     * @return string|null
      */
-    public function __toString(): string
+    public function __toString(): ?string
     {
         return $this->originalPath;
     }
@@ -274,7 +274,7 @@ public function offsetExists($offset): bool
      *
      * @param int $offset offset
      *
-     * @return null
+     * @return DiffChunk|null
      */
     public function offsetGet($offset)
     {
@@ -284,7 +284,7 @@ public function offsetGet($offset)
     /**
      * ArrayAccess interface
      *
-     * @param int   $offset offset
+     * @param int|null   $offset offset
      * @param mixed $value  value
      */
     public function offsetSet($offset, $value): void
diff --git a/src/GitElephant/Objects/Log.php b/src/GitElephant/Objects/Log.php
index f6e2b06a..24a0f07b 100644
--- a/src/GitElephant/Objects/Log.php
+++ b/src/GitElephant/Objects/Log.php
@@ -95,7 +95,7 @@ public function __construct(
      * @param string  $ref         treeish reference
      * @param string  $path        path
      * @param int     $limit       limit
-     * @param string  $offset      offset
+     * @param int  $offset      offset
      * @param boolean $firstParent first parent
      *
      * @throws \RuntimeException
@@ -128,11 +128,7 @@ private function parseOutputLines(array $outputLines): void
         $commits = Utilities::pregSplitFlatArray($outputLines, '/^commit (\w+)$/');
 
         foreach ($commits as $commitOutputLines) {
-            if (is_string($commitOutputLines)) {
-                $this->commits[] = Commit::createFromOutputLines($this->getRepository(), [$commitOutputLines]);
-            } elseif (is_iterable($commitOutputLines)) {
-                $this->commits[] = Commit::createFromOutputLines($this->getRepository(), $commitOutputLines);
-            }
+            $this->commits[] = Commit::createFromOutputLines($this->getRepository(), $commitOutputLines);
         }
     }
 
@@ -208,6 +204,7 @@ public function offsetGet($offset): ?\GitElephant\Objects\Commit
      * @param int   $offset offset
      * @param mixed $value  value
      *
+     * @return void
      * @throws \RuntimeException
      */
     public function offsetSet($offset, $value)
@@ -220,6 +217,7 @@ public function offsetSet($offset, $value)
      *
      * @param int $offset offset
      *
+     * @return void
      * @throws \RuntimeException
      */
     public function offsetUnset($offset)
diff --git a/src/GitElephant/Objects/LogRange.php b/src/GitElephant/Objects/LogRange.php
index 66784adc..7678a5dc 100644
--- a/src/GitElephant/Objects/LogRange.php
+++ b/src/GitElephant/Objects/LogRange.php
@@ -52,9 +52,9 @@ class LogRange implements \ArrayAccess, \Countable, \Iterator
      * @param \GitElephant\Repository $repository  repo
      * @param string                  $refStart    starting reference (excluded from the range)
      * @param string                  $refEnd      ending reference
-     * @param null                    $path        path
+     * @param string|null                   $path        path
      * @param int                     $limit       limit
-     * @param null                    $offset      offset
+     * @param int                   $offset      offset
      * @param boolean                 $firstParent first parent
      *
      * @throws \RuntimeException
@@ -66,7 +66,7 @@ public function __construct(
         $refEnd,
         $path = null,
         int $limit = 15,
-        int $offset = null,
+        int $offset = 0,
         bool $firstParent = false
     ) {
         $this->repository = $repository;
@@ -80,7 +80,7 @@ public function __construct(
      * @param string  $refEnd      treeish reference
      * @param string  $path        path
      * @param int     $limit       limit
-     * @param string  $offset      offset
+     * @param int  $offset      offset
      * @param boolean $firstParent first parent
      *
      * @throws \RuntimeException
@@ -94,7 +94,7 @@ private function createFromCommand(
         $refEnd,
         $path = null,
         int $limit = 15,
-        int $offset = null,
+        int $offset = 0,
         bool $firstParent = false
     ): void {
         $command = LogRangeCommand::getInstance($this->getRepository())->showLog(
@@ -205,6 +205,7 @@ public function offsetGet($offset): ?\GitElephant\Objects\Commit
      * @param int   $offset offset
      * @param mixed $value  value
      *
+     * @return void
      * @throws \RuntimeException
      */
     public function offsetSet($offset, $value)
@@ -217,6 +218,7 @@ public function offsetSet($offset, $value)
      *
      * @param int $offset offset
      *
+     * @return void
      * @throws \RuntimeException
      */
     public function offsetUnset($offset)
@@ -227,7 +229,7 @@ public function offsetUnset($offset)
     /**
      * Countable interface
      *
-     * @return int|void
+     * @return int
      */
     public function count(): int
     {
diff --git a/src/GitElephant/Objects/Remote.php b/src/GitElephant/Objects/Remote.php
index 696fe6b6..3611fbc9 100644
--- a/src/GitElephant/Objects/Remote.php
+++ b/src/GitElephant/Objects/Remote.php
@@ -67,7 +67,7 @@ class Remote
     private $remoteHEAD = null;
 
     /**
-     * @var array
+     * @var array<Branch>
      */
     private $branches;
 
@@ -75,13 +75,12 @@ class Remote
      * Class constructor
      *
      * @param \GitElephant\Repository $repository   repository instance
-     * @param string                  $name         remote name
+     * @param string|null                  $name         remote name
      * @param bool                    $queryRemotes Do not fetch new information from remotes
      *
      * @throws \RuntimeException
      * @throws \InvalidArgumentException
      * @throws \UnexpectedValueException
-     * @return \GitElephant\Objects\Remote
      */
     public function __construct(Repository $repository, string $name = null, bool $queryRemotes = true)
     {
@@ -90,8 +89,6 @@ public function __construct(Repository $repository, string $name = null, bool $q
             $this->name = trim($name);
             $this->createFromCommand($queryRemotes);
         }
-
-        return $this;
     }
 
     /**
@@ -120,7 +117,7 @@ public static function pick(
      * @throws \Symfony\Component\Process\Exception\LogicException
      * @throws \Symfony\Component\Process\Exception\InvalidArgumentException
      * @throws \Symfony\Component\Process\Exception\RuntimeException
-     * @return array
+     * @return array<string>
      */
     public function getVerboseOutput(RemoteCommand $remoteCmd = null): array
     {
@@ -146,7 +143,7 @@ public function getVerboseOutput(RemoteCommand $remoteCmd = null): array
      * @throws \Symfony\Component\Process\Exception\LogicException
      * @throws \Symfony\Component\Process\Exception\InvalidArgumentException
      * @throws \Symfony\Component\Process\Exception\RuntimeException
-     * @return array
+     * @return array<string>
      */
     public function getShowOutput(
         string $name = null,
@@ -199,11 +196,11 @@ private function createFromCommand(bool $queryRemotes = true): self
     /**
      * parse details from remote show
      *
-     * @param array|string $remoteDetails Output lines for a remote show
+     * @param array $remoteDetails Output lines for a remote show
      *
      * @throws \UnexpectedValueException
      */
-    public function parseOutputLines(array $remoteDetails)
+    public function parseOutputLines(array $remoteDetails): void
     {
         array_filter($remoteDetails);
         $name = array_shift($remoteDetails);
@@ -250,7 +247,7 @@ public function parseOutputLines(array $remoteDetails)
                 $groups['localRefs'] = $lineno;
             }
         }
-        
+
         $this->setBranches($this->aggregateBranchDetails($groups, $remoteDetails));
     }
 
@@ -262,7 +259,7 @@ public function parseOutputLines(array $remoteDetails)
      *                             are respective of the "group" detail present in $remoteDetails
      * @param array $remoteDetails Output of git-remote show [name]
      *
-     * @return array
+     * @return array<array<string>>
      */
     protected function aggregateBranchDetails($groupLines, $remoteDetails): array
     {
@@ -301,9 +298,9 @@ protected function aggregateBranchDetails($groupLines, $remoteDetails): array
     /**
      * parse the details related to remote branch references
      *
-     * @param array $lines
+     * @param array<string> $lines
      *
-     * @return array
+     * @return array // <string, array<string, string>>
      */
     public function parseRemoteBranches(array $lines): array
     {
@@ -325,9 +322,9 @@ public function parseRemoteBranches(array $lines): array
      * parse the details related to local branches and the remotes that they
      * merge with
      *
-     * @param array $lines
+     * @param array<string> $lines
      *
-     * @return array
+     * @return array // <array<string>>
      */
     public function parseLocalPullBranches($lines): array
     {
@@ -349,9 +346,9 @@ public function parseLocalPullBranches($lines): array
      * parse the details related to local branches and the remotes that they
      * push to
      *
-     * @param array $lines
+     * @param array<string> $lines
      *
-     * @return array
+     * @return array // <array<string>>
      */
     public function parseLocalPushRefs($lines): array
     {
diff --git a/src/GitElephant/Objects/Tree.php b/src/GitElephant/Objects/Tree.php
index d5162dc6..29444f6a 100644
--- a/src/GitElephant/Objects/Tree.php
+++ b/src/GitElephant/Objects/Tree.php
@@ -36,28 +36,28 @@
 class Tree extends NodeObject implements \ArrayAccess, \Countable, \Iterator
 {
     /**
-     * @var string
+     * @var string|null
      */
     private $ref;
 
     /**
      * the cursor position
      *
-     * @var int
+     * @var int|null
      */
     private $position;
 
     /**
      * the tree subject
      *
-     * @var NodeObject
+     * @var NodeObject|null
      */
     private $subject;
 
     /**
      * tree children
      *
-     * @var array
+     * @var array<TreeObject>
      */
     private $children = [];
 
@@ -71,7 +71,7 @@ class Tree extends NodeObject implements \ArrayAccess, \Countable, \Iterator
     /**
      * the blob of the actual tree
      *
-     * @var \GitElephant\Objects\NodeObject
+     * @var \GitElephant\Objects\NodeObject|null
      */
     private $blob;
 
@@ -249,7 +249,7 @@ public function getBreadcrumb(): array
      *
      * @param array $outputLines output lines
      *
-     * @return mixed
+     * @return void
      */
     private function scanPathsForBlob(array $outputLines): void
     {
@@ -297,7 +297,7 @@ private static function sortChildren(NodeObject $a, NodeObject $b): int
      *
      * @param string $line a single line output from the git binary
      *
-     * @return mixed
+     * @return void
      */
     private function parseLine(string $line): void
     {
@@ -393,7 +393,7 @@ public function getLastCommit($ref = 'master'): ?\GitElephant\Objects\Commit
     /**
      * get the tree object for this tree
      *
-     * @return \GitElephant\Objects\NodeObject
+     * @return \GitElephant\Objects\NodeObject|null
      */
     public function getObject(): ?\GitElephant\Objects\NodeObject
     {
@@ -403,9 +403,9 @@ public function getObject(): ?\GitElephant\Objects\NodeObject
     /**
      * Blob getter
      *
-     * @return \GitElephant\Objects\NodeObject
+     * @return \GitElephant\Objects\NodeObject|null
      */
-    public function getBlob(): \GitElephant\Objects\NodeObject
+    public function getBlob(): ?\GitElephant\Objects\NodeObject
     {
         return $this->blob;
     }
@@ -413,9 +413,9 @@ public function getBlob(): \GitElephant\Objects\NodeObject
     /**
      * Get Subject
      *
-     * @return \GitElephant\Objects\NodeObject
+     * @return \GitElephant\Objects\NodeObject|null
      */
-    public function getSubject(): \GitElephant\Objects\NodeObject
+    public function getSubject(): ?\GitElephant\Objects\NodeObject
     {
         return $this->subject;
     }
@@ -423,9 +423,9 @@ public function getSubject(): \GitElephant\Objects\NodeObject
     /**
      * Get Ref
      *
-     * @return string
+     * @return string|null
      */
-    public function getRef(): string
+    public function getRef(): ?string
     {
         return $this->ref;
     }
@@ -448,7 +448,7 @@ public function offsetExists($offset): bool
      *
      * @param int $offset offset
      *
-     * @return null
+     * @return NodeObject|null
      */
     public function offsetGet($offset)
     {
@@ -458,8 +458,8 @@ public function offsetGet($offset)
     /**
      * ArrayAccess interface
      *
-     * @param int   $offset offset
-     * @param mixed $value  value
+     * @param int|null   $offset offset
+     * @param TreeObject $value  value
      */
     public function offsetSet($offset, $value): void
     {
@@ -493,9 +493,9 @@ public function count(): int
     /**
      * Iterator interface
      *
-     * @return mixed
+     * @return TreeObject|null
      */
-    public function current()
+    public function current(): ?TreeObject
     {
         return $this->children[$this->position];
     }
diff --git a/src/GitElephant/Objects/TreeishInterface.php b/src/GitElephant/Objects/TreeishInterface.php
index 97174e25..405270fa 100644
--- a/src/GitElephant/Objects/TreeishInterface.php
+++ b/src/GitElephant/Objects/TreeishInterface.php
@@ -32,12 +32,12 @@ interface TreeishInterface
      *
      * @abstract
      */
-    public function getSha();
+    public function getSha(): ?string;
 
     /**
      * toString magic method, should return the sha of the treeish
      *
      * @abstract
      */
-    public function __toString();
+    public function __toString(): string;
 }
diff --git a/src/GitElephant/Repository.php b/src/GitElephant/Repository.php
index 4e3bb934..4c8f1fd6 100644
--- a/src/GitElephant/Repository.php
+++ b/src/GitElephant/Repository.php
@@ -78,7 +78,7 @@ class Repository
     /**
      * the caller instance
      *
-     * @var \GitElephant\Command\Caller\Caller
+     * @var \GitElephant\Command\Caller\CallerInterface
      */
     private $caller;
 
@@ -145,9 +145,9 @@ public static function open($repositoryPath, string $binary = null, $name = null
      * and save it in a temp folder
      *
      * @param string|Repository $git            the git remote url, or the filesystem path
-     * @param null              $repositoryPath path
+     * @param string|null             $repositoryPath path
      * @param string|null $binary         the path to the git binary
-     * @param null              $name           repository name
+     * @param string|null             $name           repository name
      *
      * @throws \RuntimeException
      * @throws \Symfony\Component\Filesystem\Exception\IOException
@@ -224,7 +224,11 @@ public function stage($path = '.'): self
      */
     public function unstage($path): self
     {
-        $this->caller->execute(MainCommand::getInstance($this)->unstage($path), true, null, [0, 1]);
+        if ($this->caller instanceof Caller) {
+            $this->caller->execute(MainCommand::getInstance($this)->unstage($path), true, null, [0, 1]);
+        } else {
+            $this->caller->execute(MainCommand::getInstance($this)->unstage($path), true, null);
+        }
 
         return $this;
     }
@@ -313,7 +317,7 @@ public function commit(string $message, $stageAll = false, $ref = null, $author
      * @throws \Symfony\Component\Process\Exception\RuntimeException
      * @return array
      */
-    public function revParse(string $arg = null, array $options = []): array
+    public function revParse($arg = null, array $options = []): array
     {
         $this->caller->execute(RevParseCommand::getInstance()->revParse($arg, $options));
 
@@ -408,7 +412,7 @@ public function getStatusOutput(): array
      * Create a new branch
      *
      * @param string $name       the new branch name
-     * @param null   $startPoint the reference to create the branch from
+     * @param string|null  $startPoint the reference to create the branch from
      *
      * @throws \RuntimeException
      * @throws \Symfony\Component\Process\Exception\RuntimeException
@@ -603,8 +607,8 @@ public function merge(Branch $branch, string $message = '', string $mode = 'auto
      * This function change the state of the repository on the filesystem
      *
      * @param string $name       The new tag name
-     * @param null   $startPoint The reference to create the tag from
-     * @param null   $message    the tag message
+     * @param string|null  $startPoint The reference to create the tag from
+     * @param string|null  $message    the tag message
      *
      * @throws \RuntimeException
      * @throws \Symfony\Component\Process\Exception\RuntimeException
@@ -784,9 +788,9 @@ public function getBranchOrTag(string $name)
         }
 
         $tagFinderOutput = $this->caller
-            ->execute(TagCommand::getInstance($this)
-            ->listTags())->getOutputLines(true);
-        
+            ->execute(TagCommand::getInstance($this)->listTags())
+            ->getOutputLines(true);
+
         foreach ($tagFinderOutput as $line) {
             if ($line === $name) {
                 return new Tag($this, $name);
@@ -830,7 +834,7 @@ public function countCommits($start = 'HEAD'): int
      *
      * @param string|TreeishInterface|array $ref         the treeish to check, as a string, as an object or as an array
      * @param string|NodeObject             $path        the physical path to the tree relative to the repository root
-     * @param int|null                      $limit       limit to n entries
+     * @param int                      $limit       limit to n entries
      * @param int|null                      $offset      skip n entries
      * @param boolean|false                 $firstParent skip commits brought in to branch by a merge
      *
@@ -840,7 +844,7 @@ public function getLog(
         $ref = 'HEAD',
         $path = null,
         int $limit = 10,
-        int $offset = null,
+        ?int $offset = null,
         bool $firstParent = false
     ): \GitElephant\Objects\Log {
         return new Log($this, $ref, $path, $limit, $offset, $firstParent);
@@ -852,7 +856,7 @@ public function getLog(
      * @param string            $refStart
      * @param string            $refEnd
      * @param string|NodeObject $path        the physical path to the tree relative to the repository root
-     * @param int|null          $limit       limit to n entries
+     * @param int          $limit       limit to n entries
      * @param int|null          $offset      skip n entries
      * @param boolean|false     $firstParent skip commits brought in to branch by a merge
      *
@@ -957,8 +961,8 @@ public function getTree($ref = 'HEAD', $path = null): \GitElephant\Objects\Tree
     /**
      * Get a Diff object for a commit with its parent, by default the diff is between the current head and its parent
      *
-     * @param \GitElephant\Objects\Commit|string      $commit1 A TreeishInterface instance
-     * @param \GitElephant\Objects\Commit|string|null $commit2 A TreeishInterface instance
+     * @param \GitElephant\Objects\Commit|TreeishInterface|string|null $commit1 The first commit to compare
+     * @param \GitElephant\Objects\Commit|TreeishInterface|string|null $commit2 The commit to compare to
      * @param null|string|NodeObject                  $path    The path to get the diff for or a Object instance
      *
      * @throws \RuntimeException
@@ -966,9 +970,9 @@ public function getTree($ref = 'HEAD', $path = null): \GitElephant\Objects\Tree
      * @return Objects\Diff\Diff
      */
     public function getDiff(
-        string $commit1 = null,
-        string $commit2 = null,
-        string $path = null
+        $commit1 = null,
+        $commit2 = null,
+        $path = null
     ): \GitElephant\Objects\Diff\Diff {
         return Diff::create($this, $commit1, $commit2, $path);
     }
@@ -977,7 +981,7 @@ public function getDiff(
      * Clone a repository
      *
      * @param string      $url           the repository url (i.e. git://github.com/matteosister/GitElephant.git)
-     * @param null        $to            where to clone the repo
+     * @param string|null       $to            where to clone the repo
      * @param string|null $repoReference Repo reference to clone. Required if performing a shallow clone.
      * @param int|null    $depth         Depth to clone repo. Specify 1 to perform a shallow clone
      * @param bool        $recursive     Whether to recursively clone child repos.
@@ -1346,11 +1350,11 @@ public function stashList(array $options = null): array
     /**
      * Shows details for a stash
      *
-     * @param string $stash
+     * @param string|int $stash
      *
      * @return string
      */
-    public function stashShow(string $stash): string
+    public function stashShow($stash): string
     {
         $stashCommand = StashCommand::getInstance($this);
         $command = $stashCommand->show($stash);
@@ -1362,9 +1366,9 @@ public function stashShow(string $stash): string
     /**
      * Drops a stash
      *
-     * @param string $stash
+     * @param string|int $stash
      */
-    public function stashDrop(string $stash): void
+    public function stashDrop($stash): void
     {
         $stashCommand = StashCommand::getInstance($this);
         $command = $stashCommand->drop($stash);
@@ -1374,10 +1378,10 @@ public function stashDrop(string $stash): void
     /**
      * Applies a stash
      *
-     * @param string  $stash
+     * @param string|int $stash
      * @param boolean $index
      */
-    public function stashApply(string $stash, bool $index = false): void
+    public function stashApply($stash, bool $index = false): void
     {
         $stashCommand = StashCommand::getInstance($this);
         $command = $stashCommand->apply($stash, $index);
@@ -1387,10 +1391,10 @@ public function stashApply(string $stash, bool $index = false): void
     /**
      *  Applies a stash, then removes it from the stash
      *
-     * @param string  $stash
+     * @param string|int $stash
      * @param boolean $index
      */
-    public function stashPop(string $stash, bool $index = false): void
+    public function stashPop($stash, bool $index = false): void
     {
         $stashCommand = StashCommand::getInstance($this);
         $command = $stashCommand->pop($stash, $index);
@@ -1401,9 +1405,9 @@ public function stashPop(string $stash, bool $index = false): void
      *  Creates and checks out a new branch named <branchname> starting from the commit at which the <stash> was originally created
      *
      * @param string $branch
-     * @param string $stash
+     * @param string|int $stash
      */
-    public function stashBranch(string $branch, string $stash): void
+    public function stashBranch(string $branch, $stash): void
     {
         $stashCommand = StashCommand::getInstance($this);
         $command = $stashCommand->branch($branch, $stash);
diff --git a/src/GitElephant/Status/Status.php b/src/GitElephant/Status/Status.php
index f2a86414..36eccc6d 100644
--- a/src/GitElephant/Status/Status.php
+++ b/src/GitElephant/Status/Status.php
@@ -37,7 +37,7 @@ class Status
     private $repository;
 
     /**
-     * @var array
+     * @var array<StatusFile>
      */
     protected $files;
 
@@ -79,7 +79,7 @@ private function createFromCommand(): void
     /**
      * all files
      *
-     * @return Sequence
+     * @return Sequence<StatusFile>
      */
     public function all(): \PhpCollection\Sequence
     {
@@ -89,7 +89,7 @@ public function all(): \PhpCollection\Sequence
     /**
      * untracked files
      *
-     * @return Sequence
+     * @return Sequence<StatusFile>
      */
     public function untracked(): \PhpCollection\Sequence
     {
@@ -99,7 +99,7 @@ public function untracked(): \PhpCollection\Sequence
     /**
      * modified files
      *
-     * @return Sequence
+     * @return Sequence<StatusFile>
      */
     public function modified(): \PhpCollection\Sequence
     {
@@ -109,7 +109,7 @@ public function modified(): \PhpCollection\Sequence
     /**
      * added files
      *
-     * @return Sequence
+     * @return Sequence<StatusFile>
      */
     public function added(): \PhpCollection\Sequence
     {
@@ -119,7 +119,7 @@ public function added(): \PhpCollection\Sequence
     /**
      * deleted files
      *
-     * @return Sequence
+     * @return Sequence<StatusFile>
      */
     public function deleted(): \PhpCollection\Sequence
     {
@@ -129,7 +129,7 @@ public function deleted(): \PhpCollection\Sequence
     /**
      * renamed files
      *
-     * @return Sequence
+     * @return Sequence<StatusFile>
      */
     public function renamed(): \PhpCollection\Sequence
     {
@@ -139,7 +139,7 @@ public function renamed(): \PhpCollection\Sequence
     /**
      * copied files
      *
-     * @return Sequence
+     * @return Sequence<StatusFile>
      */
     public function copied(): \PhpCollection\Sequence
     {
@@ -168,7 +168,7 @@ private function parseOutputLines(array $lines): void
     /**
      * @param string $line
      *
-     * @return mixed
+     * @return array<string>|null
      */
     protected function splitStatusLine(string $line)
     {
@@ -182,7 +182,7 @@ protected function splitStatusLine(string $line)
      *
      * @param string $type
      *
-     * @return Sequence
+     * @return Sequence<StatusFile>
      */
     protected function filterByType(string $type): \PhpCollection\Sequence
     {
diff --git a/src/GitElephant/Status/StatusFile.php b/src/GitElephant/Status/StatusFile.php
index 7b8bf44f..32f37268 100644
--- a/src/GitElephant/Status/StatusFile.php
+++ b/src/GitElephant/Status/StatusFile.php
@@ -107,7 +107,7 @@ public function isRenamed(): bool
     }
 
     /**
-     * Get Name
+     * Get the file name
      *
      * @return string
      */
@@ -139,7 +139,7 @@ public function getWorkingTreeStatus(): ?string
     /**
      * description of the status
      *
-     * @return string
+     * @return void
      */
     public function calculateDescription(): void
     {
@@ -185,8 +185,13 @@ public function setDescription(string $description): void
     }
 
     /**
-     * Get Description
+     * Get Description.
+     * Note that in certain environments, git might
+     * format the output differently, leading to the description
+     * being an empty string. Use setDescription(string) to set it yourself.
      *
+     * @see #calulcateDescription()
+     * @see #setDescription($description)
      * @return string
      */
     public function getDescription(): string
@@ -209,11 +214,12 @@ public function setType(string $type): void
     }
 
     /**
-     * Get Type
+     * Get the Type of status/change.
+     * Please note that this type might not be set by default.
      *
      * @return string
      */
-    public function getType(): string
+    public function getType(): ?string
     {
         return $this->type;
     }
diff --git a/src/GitElephant/Status/StatusIndex.php b/src/GitElephant/Status/StatusIndex.php
index ecc84b63..99e81a22 100644
--- a/src/GitElephant/Status/StatusIndex.php
+++ b/src/GitElephant/Status/StatusIndex.php
@@ -30,7 +30,7 @@
 class StatusIndex extends Status
 {
     /**
-     * @return Sequence
+     * @return Sequence<StatusFile>
      */
     public function untracked(): \PhpCollection\Sequence
     {
@@ -40,7 +40,7 @@ public function untracked(): \PhpCollection\Sequence
     /**
      * all files with modified status in the index
      *
-     * @return Sequence
+     * @return Sequence<StatusFile>
      */
     public function all(): \PhpCollection\Sequence
     {
@@ -59,7 +59,7 @@ function (StatusFile $statusFile) {
      *
      * @param string $type
      *
-     * @return Sequence
+     * @return Sequence<StatusFile>
      */
     protected function filterByType(string $type): \PhpCollection\Sequence
     {
diff --git a/src/GitElephant/Utilities.php b/src/GitElephant/Utilities.php
index 76ef2d5c..260477c3 100644
--- a/src/GitElephant/Utilities.php
+++ b/src/GitElephant/Utilities.php
@@ -33,7 +33,7 @@ class Utilities
      * @param string[] $list  a flat array
      * @param string $pattern a regular expression
      *
-     * @return string[]
+     * @return array<int, array<int, string>>
      */
     public static function pregSplitArray(array $list, string $pattern): array
     {
@@ -56,7 +56,7 @@ public static function pregSplitArray(array $list, string $pattern): array
      * @param string[] $list  a flat array
      * @param string $pattern a regular expression
      *
-     * @return string[]
+     * @return array<int, array<int, string>>
      */
     public static function pregSplitFlatArray(array $list, string $pattern): array
     {
diff --git a/tests/GitElephant/Command/CallerTest.php b/tests/GitElephant/Command/CallerTest.php
index 202a4fd0..38cc2e20 100644
--- a/tests/GitElephant/Command/CallerTest.php
+++ b/tests/GitElephant/Command/CallerTest.php
@@ -76,7 +76,7 @@ public function testGetOutput(): void
         $caller = new Caller(null, $this->getRepository()->getPath());
         $mainCommand = new MainCommand();
         $caller->execute($mainCommand->init());
-        $this->assertRegExp(
+        $this->myAssertMatchesRegularExpression(
             sprintf('/^(.*)%s/', str_replace('/', '\/', $this->getRepository()->getPath())),
             $caller->getOutput()
         );
@@ -107,7 +107,7 @@ public function testGetRawOutput(): void
         $this->getRepository()->init();
         $caller = new Caller(null, $this->getRepository()->getPath());
         $caller->execute('status');
-        $this->assertRegExp('/master/', $caller->getRawOutput($caller->getRawOutput()));
+        $this->myAssertMatchesRegularExpression('/master/', $caller->getRawOutput());
     }
 
     /**
diff --git a/tests/GitElephant/Objects/CommitTest.php b/tests/GitElephant/Objects/CommitTest.php
index 60234687..f5167cfd 100644
--- a/tests/GitElephant/Objects/CommitTest.php
+++ b/tests/GitElephant/Objects/CommitTest.php
@@ -54,7 +54,7 @@ public function testCommit(): void
         $this->assertInstanceOf('\Datetime', $this->commit->getDatetimeCommitter());
         $this->assertInstanceOf('\GitElephant\Objects\Commit\Message', $this->commit->getMessage());
         $this->assertEquals('first commit', $this->commit->getMessage()->toString());
-        $this->assertRegExp('/^\w{40}$/', $this->commit->getSha());
+        $this->myAssertMatchesRegularExpression('/^\w{40}$/', $this->commit->getSha());
         $this->assertEquals([], $this->commit->getParents());
         $this->addFile('foo2');
         $mainCommand = new MainCommand();
@@ -63,7 +63,7 @@ public function testCommit(): void
         $this->getCaller()->execute($showCommand->showCommit('HEAD'));
         $this->commit = Commit::pick($this->getRepository());
         $parents = $this->commit->getParents();
-        $this->assertRegExp('/^\w{40}$/', $parents[0]);
+        $this->myAssertMatchesRegularExpression('/^\w{40}$/', $parents[0]);
     }
 
     /**
diff --git a/tests/GitElephant/Objects/Diff/DiffTest.php b/tests/GitElephant/Objects/Diff/DiffTest.php
index bd265ff7..65878a70 100644
--- a/tests/GitElephant/Objects/Diff/DiffTest.php
+++ b/tests/GitElephant/Objects/Diff/DiffTest.php
@@ -50,9 +50,23 @@ public function testDiff(): void
         $this->assertInstanceOf('\GitElephant\Objects\Diff\DiffChunk', $chunk);
         $this->assertArrayInterfaces($chunk);
         $this->assertCount(5, $chunk);
+
         foreach ($chunk as $chunkLine) {
             $this->assertInstanceOf('\GitElephant\Objects\Diff\DiffChunkLine', $chunkLine);
         }
+
+        $this->assertInstanceOf('\GitElephant\Objects\Diff\DiffChunkLineUnchanged', $chunk[0]);
+        $this->assertInstanceOf('\GitElephant\Objects\Diff\DiffChunkLineChanged', $chunk[1]);
+        $this->assertInstanceOf('\GitElephant\Objects\Diff\DiffChunkLineDeleted', $chunk[2]);
+        $this->assertInstanceOf('\GitElephant\Objects\Diff\DiffChunkLineAdded', $chunk[3]);
+        $this->assertInstanceOf('\GitElephant\Objects\Diff\DiffChunkLineUnchanged', $chunk[4]);
+        
+        $this->assertEquals(1, $chunk[0]->getOriginNumber());
+        $this->assertEquals(1, $chunk[0]->getDestNumber());
+        $this->assertEquals(2, $chunk[1]->getNumber());
+        $this->assertEquals(2, $chunk[1]->getOriginNumber());
+        $this->assertEquals(3, $chunk[4]->getDestNumber());
+        $this->assertEquals(4, $chunk[4]->getOriginNumber());
     }
 
     private function assertArrayInterfaces($obj): void
diff --git a/tests/GitElephant/Objects/RemoteTest.php b/tests/GitElephant/Objects/RemoteTest.php
index 015b146d..10bae2b2 100644
--- a/tests/GitElephant/Objects/RemoteTest.php
+++ b/tests/GitElephant/Objects/RemoteTest.php
@@ -108,9 +108,9 @@ public function sampleRemoteShowRemoteName(): string
      *
      * @return string
      */
-    public function sampleRemoteShowRemoteHEAD(): void
+    public function sampleRemoteShowRemoteHEAD(): string
     {
-        'Apollo';
+        return 'Apollo';
     }
 
     /**
diff --git a/tests/GitElephant/Objects/TreeTest.php b/tests/GitElephant/Objects/TreeTest.php
index 131bcd7c..99034549 100644
--- a/tests/GitElephant/Objects/TreeTest.php
+++ b/tests/GitElephant/Objects/TreeTest.php
@@ -88,7 +88,7 @@ public function testWithPath(): void
      */
     public function testSubmodule(): void
     {
-        $tempDir = realpath(sys_get_temp_dir()) . 'gitelephant_' . md5(uniqid(rand(), 1));
+        $tempDir = realpath(sys_get_temp_dir()) . 'gitelephant_' . md5(uniqid());
         // horrible hack because php is beautiful.
         $tempName = @tempnam($tempDir, 'gitelephant');
         $path = $tempName;
diff --git a/tests/GitElephant/RepositoryTest.php b/tests/GitElephant/RepositoryTest.php
index 7532ecdd..7b128a75 100644
--- a/tests/GitElephant/RepositoryTest.php
+++ b/tests/GitElephant/RepositoryTest.php
@@ -397,6 +397,7 @@ public function testGetObjectLog(): void
         $repo->commit('added E.txt', true);
 
         $tree = $repo->getTree();
+        /** @var NodeObject */
         $obj = $tree[0];
 
         $log = $this->getRepository()->getObjectLog($obj);
@@ -686,7 +687,7 @@ public function testMove(): void
         $this->getRepository()->commit('commit 1', true);
         $this->getRepository()->move('foo', 'bar');
         $status = $this->getRepository()->getStatusOutput();
-        $this->assertRegExp('/(.*):    foo -> bar/', implode("\n", $status));
+        $this->myAssertMatchesRegularExpression('/(.*):    foo -> bar/', implode("\n", $status));
     }
 
     /**
@@ -700,7 +701,7 @@ public function testRemove(): void
         $this->getRepository()->remove('foo');
         $status = $this->getRepository()->getStatusOutput();
 
-        $this->assertRegExp('/(.*):    foo/', implode("\n", $status));
+        $this->myAssertMatchesRegularExpression('/(.*):    foo/', implode("\n", $status));
     }
 
     /**
diff --git a/tests/GitElephant/Status/StatusTest.php b/tests/GitElephant/Status/StatusTest.php
index 5b598f0e..75f8a9e8 100644
--- a/tests/GitElephant/Status/StatusTest.php
+++ b/tests/GitElephant/Status/StatusTest.php
@@ -186,6 +186,28 @@ public function testWorkingTreeStatus(): void
         $this->assertCount(0, $index->all());
     }
 
+    /**
+     * Test the name, type and describe getter & setter
+     *
+     * @return void
+     */
+    public function testStatusFiles(): void
+    {
+        $this->addFile('test');
+        $this->repository->stage();
+        $s = $this->repository->getStatus();
+        $files = $s->all();
+        $this->assertCount(1, $files);
+        foreach ($files as $file) {
+            $this->assertEquals('test', $file->getName());
+            $this->assertEquals(null, $file->getType());
+            $file->setDescription('test');
+            $this->assertEquals('test', $file->getDescription());
+            $file->setType(StatusFile::UNMODIFIED);
+            $this->assertEquals(StatusFile::UNMODIFIED, $file->getType());
+        }
+    }
+
     /**
      * @param mixed $subject
      */
diff --git a/tests/GitElephant/TestCase.php b/tests/GitElephant/TestCase.php
index 3b11817c..75ca0e9b 100644
--- a/tests/GitElephant/TestCase.php
+++ b/tests/GitElephant/TestCase.php
@@ -36,7 +36,7 @@ class TestCase extends \PHPUnit\Framework\TestCase
     protected $caller;
 
     /**
-     * @var Repository
+     * @var Repository|array<Repository>
      */
     protected $repository;
 
@@ -51,11 +51,11 @@ class TestCase extends \PHPUnit\Framework\TestCase
     protected $finder;
 
     /**
-     * @param string $name
+     * @param string|int|null $name the name or index of the repository
      *
      * @return \GitElephant\Repository
      */
-    protected function getRepository(string $name = null)
+    protected function getRepository($name = null)
     {
         if ($this->repository == null) {
             $this->initRepository($name);
@@ -122,9 +122,12 @@ protected function tearDown(): void
     }
 
     /**
+     * Write to file. Creates the file if not existing.
+     * Overwrites content if already existing.
+     *
      * @param string      $name       file name
      * @param string|null $folder     folder name
-     * @param null        $content    content
+     * @param string|null        $content    content
      * @param Repository  $repository repository to add file to
      *
      * @return void
@@ -201,17 +204,17 @@ protected function addFolder($name): void
         $fs->mkdir($this->path . DIRECTORY_SEPARATOR . $name);
     }
 
-    protected function addSubmodule($url, $path): void
+    protected function addSubmodule(string $url, string $path): void
     {
         $this->getRepository()->addSubmodule($url, $path);
     }
 
     /**
-     * @param $classname
+     * @param string $classname
      *
      * @return MockObject
      */
-    protected function getMock($classname): MockObject
+    protected function getMock(string $classname): MockObject
     {
         return $this
             ->getMockBuilder($classname)
@@ -251,7 +254,13 @@ protected function addCommandToMockContainer(MockObject $container, string $comm
             ->willReturn($this->getMockCommand());
     }
 
-    protected function addOutputToMockRepo(MockObject $repo, array $output): void
+    /**
+     *
+     * @param MockObject $repo
+     * @param string|array $output
+     * @return void
+     */
+    protected function addOutputToMockRepo(MockObject $repo, $output): void
     {
         $repo
             ->expects($this->any())
@@ -282,17 +291,32 @@ protected function getMockRepository(): MockObject
         );
     }
 
+    /**
+     * Do a test on a certain commit
+     *
+     * @param Commit $commit the commit to test
+     * @param string $sha
+     * @param string $tree
+     * @param string $author the name of the author
+     * @param string $committer the name of the committer
+     * @param string $emailAuthor
+     * @param string $emailCommitter
+     * @param integer $datetimeAuthor
+     * @param integer $datetimeCommitter
+     * @param string $message
+     * @return void
+     */
     protected function doCommitTest(
         Commit $commit,
-        $sha,
-        $tree,
-        $author,
-        $committer,
-        $emailAuthor,
-        $emailCommitter,
-        $datetimeAuthor,
-        $datetimeCommitter,
-        $message
+        string $sha,
+        string $tree,
+        string $author,
+        string $committer,
+        string $emailAuthor,
+        string $emailCommitter,
+        int $datetimeAuthor,
+        int $datetimeCommitter,
+        string $message
     ): void {
         $this->assertInstanceOf(Commit::class, $commit);
         $this->assertEquals($sha, $commit->getSha());
@@ -309,4 +333,23 @@ protected function doCommitTest(
         $this->assertEquals($datetimeCommitter, $commit->getDatetimeCommitter()->format('U'));
         $this->assertEquals($message, $commit->getMessage()->getShortMessage());
     }
+
+    /**
+     * Compatibility function for PHP 7.2:
+     * PHPUnit 9. only supports PHP >= 7.3,
+     * but has a different compatibility regarding the assertRegex function
+     *
+     * @param string $pattern
+     * @param string $string
+     * @param string $message
+     * @return void
+     */
+    protected function myAssertMatchesRegularExpression($pattern, $string, $message = '')
+    {
+        if (method_exists($this, 'assertMatchesRegularExpression')) {
+            $this->assertMatchesRegularExpression($pattern, $string, $message);
+        } else {
+            $this->assertRegExp($pattern, $string, $message);
+        }
+    }
 }
diff --git a/tests/GitElephant/UtilitiesTest.php b/tests/GitElephant/UtilitiesTest.php
index d113195b..664cf7c1 100644
--- a/tests/GitElephant/UtilitiesTest.php
+++ b/tests/GitElephant/UtilitiesTest.php
@@ -20,6 +20,11 @@
  */
 final class UtilitiesTest extends TestCase
 {
+    /**
+     * An array containing chars
+     *
+     * @var array<string>
+     */
     private $arr = [
         'a',
         'b',
@@ -34,6 +39,11 @@ final class UtilitiesTest extends TestCase
      * @dataProvider pregSplitArrayProvider()
      *
      * @covers \GitElephant\Utilities::pregSplitArray
+     *
+     * @param array<string> $expected
+     * @param array<string> $list
+     * @param string $pattern
+     * @return void
      */
     public function testPregSplitArray(array $expected, array $list, string $pattern): void
     {
@@ -47,7 +57,11 @@ public function testPregSplitArray(array $expected, array $list, string $pattern
     }
 
     /**
+     *
+     *
      * @dataProvider
+     *
+     * @return void
      */
     public function testPregSplitFlatArray(): void
     {
@@ -61,6 +75,11 @@ public function testPregSplitFlatArray(): void
         );
     }
 
+    /**
+     * Get the array test contents
+     *
+     * @return array
+     */
     public function pregSplitArrayProvider(): array
     {
         return [