Laravel 5.6 updates

Travis config update

Removed HHVM script as Laravel no longer support HHVM after releasing 5.3

vendor/dragonmantank/cron-expression/tests/Cron/FieldFactoryTest.php

@@ -0,0 +1,42 @@
+<?php
+
+namespace Cron\Tests;
+
+use Cron\FieldFactory;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @author Michael Dowling <mtdowling@gmail.com>
+ */
+class FieldFactoryTest extends TestCase
+{
+    /**
+     * @covers \Cron\FieldFactory::getField
+     */
+    public function testRetrievesFieldInstances()
+    {
+        $mappings = array(
+            0 => 'Cron\MinutesField',
+            1 => 'Cron\HoursField',
+            2 => 'Cron\DayOfMonthField',
+            3 => 'Cron\MonthField',
+            4 => 'Cron\DayOfWeekField',
+        );
+
+        $f = new FieldFactory();
+
+        foreach ($mappings as $position => $class) {
+            $this->assertSame($class, get_class($f->getField($position)));
+        }
+    }
+
+    /**
+     * @covers \Cron\FieldFactory::getField
+     * @expectedException InvalidArgumentException
+     */
+    public function testValidatesFieldPosition()
+    {
+        $f = new FieldFactory();
+        $f->getField(-1);
+    }
+}