Cover endOfPeriod method of the Navigation class

The custom frequency requires a timezone configuration, forcing it
to run in the integration test scope.

Running the integration tests requires a database connection in the
build process. It enables other case tests.

The API Tests cause interference in other tests, requiring isolating
them.

phpunit.xml

@@ -33,6 +33,7 @@
          stopOnFailure="true">
     <php>
         <env name="APP_ENV" value="testing"/>
+        <env name="DB_HOST" value="127.0.0.1"/>
         <env name="CACHE_DRIVER" value="array"/>
         <env name="SESSION_DRIVER" value="array"/>
         <env name="QUEUE_DRIVER" value="sync"/>