Let travis run more PHP versions and run phpunit

.gitattributes

@@ -6,3 +6,7 @@
 /box.json export-ignore
 /examples export-ignore
 /phpcs.xml export-ignore
+/phpunit.xml export-ignore
+/tests export-ignore
+
+/examples linguist-documentation

.travis.yml

@@ -1,13 +1,13 @@
 language: php
 php:
 - '7.0'
-before_install:
-- composer global require kherge/box --prefer-dist
+- '7.1'
+- nightly
 install:
 - composer install --prefer-dist
-script:
-- true
 after_success:
+- composer global require kherge/box --prefer-dist
+- composer install --no-dev
 - ~/.composer/vendor/bin/box build --no-interaction
 deploy:
   skip_cleanup: true
@@ -18,3 +18,4 @@ deploy:
   on:
     repo: spejder/msml
     tags: true
+    php: '7.0'

composer.json

@@ -23,6 +23,7 @@
     ],
     "require-dev": {
         "squizlabs/php_codesniffer": "^3.0",
-        "kherge/box": "^2.7"
+        "kherge/box": "^2.7",
+        "phpunit/phpunit": "^6.1"
     }
 }

phpunit.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit bootstrap="./vendor/autoload.php"
+         colors="true"
+         stopOnFailure="false">
+    <testsuites>
+        <testsuite>
+            <directory>./tests</directory>
+        </testsuite>
+    </testsuites>
+</phpunit>

tests/README.md

@@ -0,0 +1 @@
+# Test cases