diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index 6d29a52..b7f5351 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -45,6 +45,8 @@ jobs:
         run: "php vendor/bin/phpcs src"
 #      - name: "PHPStan"
 #        run: "php vendor/bin/phpstan analyze src"
+      - name: Remove vendor directory for integration testing
+        run: rm -rf vendor
       - name: Setup Drupal
         run: |
           COMPOSER_MEMORY_LIMIT=-1 composer create-project drupal/recommended-project:${{ matrix.drupal }} ~/drupal --no-interaction
@@ -52,7 +54,7 @@ jobs:
           composer config minimum-stability dev
           composer config prefer-stable true
           composer config preferred-install dist
-          composer config repositories.0 path $GITHUB_WORKSPACE
+          composer config repositories.0 "{\"type\": \"path\", \"url\": \"$GITHUB_WORKSPACE\", \"options\": {\"symlink\": false}}"
           composer config repositories.1 composer https://packages.drupal.org/8
           COMPOSER_MEMORY_LIMIT=-1 composer require drupal/core-dev:${{ matrix.drupal }} --with-all-dependencies
       - name: "Add phpspec/prophecy-phpunit"
@@ -67,8 +69,63 @@ jobs:
       - name: "Analyze core/install.php"
         run: |
           cd ~/drupal
-          ./vendor/bin/drupal-check web/core/install.php
+          ./vendor/bin/drupal-check -vvv web/core/install.php
       - name: "Analyze dynamic_page_cache"
         run: |
           cd ~/drupal
-          ./vendor/bin/drupal-check web/core/modules/dynamic_page_cache || if (($? == 255)); then false; else true; fi
+          ./vendor/bin/drupal-check -vvv web/core/modules/dynamic_page_cache || if (($? == 255)); then false; else true; fi
+
+  contrib:
+    runs-on: "ubuntu-latest"
+    name: "${{ matrix.project }} | PHP ${{ matrix.php-version }} | Drupal ${{ matrix.drupal }}"
+    strategy:
+      matrix:
+        include:
+          - php-version: "7.3"
+            drupal: "~8.9"
+            project: config_update
+            additional_projects: ''
+            type: module
+          - php-version: "7.3"
+            drupal: "~8.9"
+            project: blazy
+            additional_projects: 'drupal/token drupal/ctools'
+            type: module
+    steps:
+      - name: "Checkout"
+        uses: "actions/checkout@v2"
+      - name: "Install PHP"
+        uses: "shivammathur/setup-php@v2"
+        with:
+          coverage: "none"
+          php-version: "${{ matrix.php-version }}"
+          tools: composer:v2
+          extensions: dom, curl, libxml, mbstring, zip, pdo, mysql, pdo_mysql, bcmath, gd, exif, iconv
+      - name: Setup Drupal
+        run: |
+          COMPOSER_MEMORY_LIMIT=-1 composer create-project drupal/recommended-project:${{ matrix.drupal }} ~/drupal --no-interaction
+          cd ~/drupal
+          composer config minimum-stability dev
+          composer config prefer-stable true
+          composer config preferred-install dist
+          composer config repositories.0 "{\"type\": \"path\", \"url\": \"$GITHUB_WORKSPACE\", \"options\": {\"symlink\": false}}"
+          composer config repositories.1 composer https://packages.drupal.org/8
+          COMPOSER_MEMORY_LIMIT=-1 composer require drupal/core-dev:${{ matrix.drupal }} --with-all-dependencies
+      - name: "Add phpspec/prophecy-phpunit"
+        run: |
+          cd ~/drupal
+          COMPOSER_MEMORY_LIMIT=-1 composer require --dev phpspec/prophecy-phpunit:^2
+        if: ${{ matrix.drupal == '^9.0' }}
+      - name: "require drupal-check"
+        run: |
+          cd ~/drupal
+          COMPOSER_MEMORY_LIMIT=-1 composer require mglaman/drupal-check *@dev
+      - name: "verify drupal-check version"
+        run: |
+          cd ~/drupal
+          ./vendor/bin/drupal-check --version
+      - name: 'Check ${{ matrix.project }}'
+        run: |
+          cd ~/drupal
+          COMPOSER_MEMORY_LIMIT=-1 composer require drupal/${{ matrix.project }} ${{ matrix.additional_projects }}
+          ./vendor/bin/drupal-check -vvv web/${{ matrix.type }}s/contrib/${{ matrix.project }} --no-progress || if (($? == 255 || $? == 127)); then false; else true; fi
diff --git a/composer.json b/composer.json
index 1f37630..50b8c0b 100644
--- a/composer.json
+++ b/composer.json
@@ -15,13 +15,13 @@
         "jean85/pretty-package-versions": "^1.5.0 || ^2.0.1",
         "mglaman/phpstan-drupal": "^0.12.8",
         "nette/neon": "^3.1",
+        "phpstan/phpstan-deprecation-rules": "^0.12.6",
         "symfony/console": "~3.2 || ~4.0",
         "symfony/process": "~3.2 || ~4.0",
         "webflo/drupal-finder": "^1.1"
     },
     "require-dev": {
         "phpstan/phpstan": "^0.12.81",
-        "phpstan/phpstan-deprecation-rules": "^0.12.6",
         "phpstan/phpstan-strict-rules": "^0.12.9",
         "squizlabs/php_codesniffer": "^3.4"
     },
diff --git a/composer.lock b/composer.lock
index 4132cc8..1fa72f8 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "f4050c285b6019c923376b498c756243",
+    "content-hash": "57f0b2c8e882be236d754290fadd466c",
     "packages": [
         {
             "name": "composer/xdebug-handler",
@@ -506,6 +506,57 @@
             ],
             "time": "2021-03-08T22:03:02+00:00"
         },
+        {
+            "name": "phpstan/phpstan-deprecation-rules",
+            "version": "0.12.6",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/phpstan/phpstan-deprecation-rules.git",
+                "reference": "46dbd43c2db973d2876d6653e53f5c2cc3a01fbb"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/phpstan/phpstan-deprecation-rules/zipball/46dbd43c2db973d2876d6653e53f5c2cc3a01fbb",
+                "reference": "46dbd43c2db973d2876d6653e53f5c2cc3a01fbb",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^7.1 || ^8.0",
+                "phpstan/phpstan": "^0.12.60"
+            },
+            "require-dev": {
+                "phing/phing": "^2.16.3",
+                "php-parallel-lint/php-parallel-lint": "^1.2",
+                "phpstan/phpstan-phpunit": "^0.12",
+                "phpunit/phpunit": "^7.5.20"
+            },
+            "type": "phpstan-extension",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "0.12-dev"
+                },
+                "phpstan": {
+                    "includes": [
+                        "rules.neon"
+                    ]
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "PHPStan\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "description": "PHPStan rules for detecting usage of deprecated classes, methods, properties, constants and traits.",
+            "support": {
+                "issues": "https://github.com/phpstan/phpstan-deprecation-rules/issues",
+                "source": "https://github.com/phpstan/phpstan-deprecation-rules/tree/0.12.6"
+            },
+            "time": "2020-12-13T10:20:54+00:00"
+        },
         {
             "name": "psr/container",
             "version": "1.1.1",
@@ -1271,57 +1322,6 @@
         }
     ],
     "packages-dev": [
-        {
-            "name": "phpstan/phpstan-deprecation-rules",
-            "version": "0.12.6",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/phpstan/phpstan-deprecation-rules.git",
-                "reference": "46dbd43c2db973d2876d6653e53f5c2cc3a01fbb"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/phpstan/phpstan-deprecation-rules/zipball/46dbd43c2db973d2876d6653e53f5c2cc3a01fbb",
-                "reference": "46dbd43c2db973d2876d6653e53f5c2cc3a01fbb",
-                "shasum": ""
-            },
-            "require": {
-                "php": "^7.1 || ^8.0",
-                "phpstan/phpstan": "^0.12.60"
-            },
-            "require-dev": {
-                "phing/phing": "^2.16.3",
-                "php-parallel-lint/php-parallel-lint": "^1.2",
-                "phpstan/phpstan-phpunit": "^0.12",
-                "phpunit/phpunit": "^7.5.20"
-            },
-            "type": "phpstan-extension",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "0.12-dev"
-                },
-                "phpstan": {
-                    "includes": [
-                        "rules.neon"
-                    ]
-                }
-            },
-            "autoload": {
-                "psr-4": {
-                    "PHPStan\\": "src/"
-                }
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "description": "PHPStan rules for detecting usage of deprecated classes, methods, properties, constants and traits.",
-            "support": {
-                "issues": "https://github.com/phpstan/phpstan-deprecation-rules/issues",
-                "source": "https://github.com/phpstan/phpstan-deprecation-rules/tree/0.12.6"
-            },
-            "time": "2020-12-13T10:20:54+00:00"
-        },
         {
             "name": "phpstan/phpstan-strict-rules",
             "version": "0.12.9",
diff --git a/src/Command/CheckCommand.php b/src/Command/CheckCommand.php
index 3f36ed5..0361791 100644
--- a/src/Command/CheckCommand.php
+++ b/src/Command/CheckCommand.php
@@ -2,7 +2,6 @@
 
 namespace DrupalCheck\Command;
 
-use DrupalCheck\Util\Tty;
 use DrupalFinder\DrupalFinder;
 use Nette\Neon\Neon;
 use PHPStan\ShouldNotHappenException;
@@ -179,6 +178,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
         $pharPath = \Phar::running();
         if ($pharPath !== '') {
             // Running in packaged Phar archive.
+            $output->writeln('<comment>Assumed running as Phar</comment>', OutputInterface::VERBOSITY_DEBUG);
             $phpstanBin = \realpath('vendor/phpstan/phpstan/phpstan.phar');
             $configuration_data['parameters']['bootstrapFiles'] = [\realpath($pharPath . '/error-bootstrap.php')];
             $configuration_data['includes'] = [
@@ -187,6 +187,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
             ];
         } elseif (file_exists(__DIR__ . '/../../vendor/autoload.php')) {
             // Running as a project dependency.
+            $output->writeln('<comment>Assumed running as local dependency</comment>', OutputInterface::VERBOSITY_DEBUG);
             $phpstanBin = \realpath(__DIR__ . '/../../vendor/phpstan/phpstan/phpstan.phar');
             $configuration_data['parameters']['bootstrapFiles'] = [\realpath(__DIR__ . '/../../error-bootstrap.php')];
             $configuration_data['includes'] = [
@@ -195,6 +196,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
             ];
         } elseif (file_exists(__DIR__ . '/../../../../autoload.php')) {
             // Running as a global dependency.
+            $output->writeln('<comment>Assumed running as global dependency</comment>', OutputInterface::VERBOSITY_DEBUG);
             $phpstanBin = \realpath(__DIR__ . '/../../../../phpstan/phpstan/phpstan.phar');
             $configuration_data['parameters']['bootstrapFiles'] = [\realpath(__DIR__ . '/../../error-bootstrap.php')];
             // The phpstan/extension-installer doesn't seem to register.