improved invoices with new renderer (#306)

* added docx renderer and demo template
* added csv renderer and demo template
* added xlsx renderer and demo template
* added ods renderer and demo template
* added user calculator
* added invoice documentation

tests/Model/InvoiceModelTest.php

@@ -0,0 +1,65 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Tests\Model;
+
+use App\Entity\Customer;
+use App\Entity\InvoiceTemplate;
+use App\Entity\Timesheet;
+use App\Invoice\Calculator\DefaultCalculator;
+use App\Invoice\NumberGenerator\DateNumberGenerator;
+use App\Model\InvoiceModel;
+use App\Repository\Query\InvoiceQuery;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @covers \App\Model\InvoiceModel
+ */
+class InvoiceModelTest extends TestCase
+{
+    public function testDefaultValues()
+    {
+        $sut = new InvoiceModel();
+        $this->assertNull($sut->getNumberGenerator());
+        $this->assertNull($sut->getCalculator());
+        $this->assertNull($sut->getTemplate());
+        $this->assertNull($sut->getCustomer());
+        $this->assertNull($sut->getQuery());
+        $this->assertNull($sut->getDueDate());
+        $this->assertEmpty($sut->getEntries());
+        $this->assertInternalType('array', $sut->getEntries());
+        $this->assertInstanceOf(\DateTime::class, $sut->getInvoiceDate());
+    }
+
+    public function testSetter()
+    {
+        $sut = new InvoiceModel();
+
+        $sut->setTemplate((new InvoiceTemplate())->setDueDays(10));
+        $sut->setCustomer(new Customer());
+        $sut->setQuery(new InvoiceQuery());
+        $sut->setEntries([new Timesheet()]);
+        $sut->setNumberGenerator(new DateNumberGenerator());
+        $sut->setCalculator(new DefaultCalculator());
+
+        $this->assertInstanceOf(DateNumberGenerator::class, $sut->getNumberGenerator());
+        $this->assertInstanceOf(DefaultCalculator::class, $sut->getCalculator());
+        $this->assertInstanceOf(InvoiceTemplate::class, $sut->getTemplate());
+        $this->assertInstanceOf(Customer::class, $sut->getCustomer());
+        $this->assertInstanceOf(InvoiceQuery::class, $sut->getQuery());
+        $this->assertInstanceOf(\DateTime::class, $sut->getDueDate());
+        $this->assertInstanceOf(Timesheet::class, $sut->getEntries()[0]);
+        $this->assertInstanceOf(\DateTime::class, $sut->getInvoiceDate());
+
+        $this->assertEquals(
+            (new \DateTime('+10 days'))->format('Y-m-d'),
+            $sut->getDueDate()->format('Y-m-d')
+        );
+    }
+}