added annotation based exporter (#1831)

* added user exporter
* added project exporter
* added customer exporter
* added activity exporter

tests/Export/Spreadsheet/Writer/XlsxWriterTest.php

@@ -0,0 +1,37 @@
+<?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\Export\Spreadsheet\Writer;
+
+use App\Export\Spreadsheet\Writer\XlsxWriter;
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @covers \App\Export\Spreadsheet\Writer\XlsxWriter
+ */
+class XlsxWriterTest extends TestCase
+{
+    public function testWriter()
+    {
+        $sut = new XlsxWriter();
+
+        self::assertEquals('xlsx', $sut->getFileExtension());
+        self::assertEquals('application/vnd.openxmlformats-officedocument.spreadsheetml.sheet', $sut->getContentType());
+
+        $spreadsheet = new Spreadsheet();
+
+        $file = $sut->save($spreadsheet);
+        self::assertInstanceOf(\SplFileInfo::class, $file);
+        self::assertTrue(file_exists($file->getRealPath()));
+
+        // TODO test autofilter
+        // TODO test freeze pane
+    }
+}