Add compatibility test to CircleCI

Author: joshcanhelp

.circleci/config.yml

@@ -20,9 +20,12 @@ commands:
           paths:
             - vendor
 
-jobs: 
-  php_7: 
-    docker: 
+jobs:
+  phpcs_compat:
+    steps:
+      - run: composer phpcs
+  php_7:
+    docker:
       - image: circleci/php:7.1
     steps:
       - prepare
@@ -46,8 +49,9 @@ workflows:
   snyk:
     jobs:
       - php_7
+      - phpcs_compat
       - snyk:
           # Must define SNYK_TOKEN env
-          context: snyk-env 
-          requires: 
-            - php_7
+          context: snyk-env
+          requires:
+            - php_7

.phpcs.xml.dist

@@ -0,0 +1,26 @@
+<?xml version="1.0"?>
+<ruleset name="Laravel-Auth0" namespace="Auth0PHP\CS\Standard">
+    <description>A custom coding standard for the Laravel Auth0 package</description>
+
+    <file>./src</file>
+
+    <!-- Only check PHP files. -->
+    <arg name="extensions" value="php"/>
+
+    <!-- Show progress, show the error codes for each message (source). -->
+    <arg value="sp"/>
+
+    <!-- Strip the filepaths down to the relevant bit. -->
+    <arg name="basepath" value="."/>
+
+    <!-- Show coloured output, if available. -->
+    <arg name="colors"/>
+
+    <!--
+    PHPCompatibility sniffs to check for PHP cross-version incompatible code.
+    https://github.com/PHPCompatibility/PHPCompatibility
+    -->
+    <config name="testVersion" value="5.5-"/>
+    <rule ref="PHPCompatibility"/>
+
+</ruleset>

composer.json

@@ -9,7 +9,15 @@
         "illuminate/contracts": "5.* | ^6.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^4 | ^7"
+        "phpunit/phpunit": "^4 | ^7",
+        "squizlabs/php_codesniffer": "^3.2",
+        "phpcompatibility/php-compatibility": "^8.1",
+        "dealerdirect/phpcodesniffer-composer-installer": "^0.5.0"
+    },
+    "scripts": {
+        "test": "SHELL_INTERACTIVE=1 \"vendor/bin/phpunit\" --coverage-text ",
+        "phpcs": "\"vendor/bin/phpcs\"",
+        "sniffs": "\"vendor/bin/phpcs\" -e"
     },
     "autoload": {
         "classmap": [