added command to create invoices via bash (#1574)

tests/Invoice/NumberGenerator/IncrementingNumberGenerator.php

@@ -0,0 +1,46 @@
+<?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\Invoice\NumberGenerator;
+
+use App\Invoice\InvoiceModel;
+use App\Invoice\NumberGeneratorInterface;
+
+class IncrementingNumberGenerator implements NumberGeneratorInterface
+{
+    private $counter = 0;
+
+    /**
+     * @param InvoiceModel $model
+     */
+    public function setModel(InvoiceModel $model)
+    {
+    }
+
+    /**
+     * @return string
+     */
+    public function getInvoiceNumber(): string
+    {
+        return $this->counter++;
+    }
+
+    /**
+     * Returns the unique ID of this number generator.
+     *
+     * Prefix it with your company name followed by a hyphen (e.g. "acme-"),
+     * if this is a third-party generator.
+     *
+     * @return string
+     */
+    public function getId(): string
+    {
+        return 'testing';
+    }
+}