improvement: cover Chart with integration test

Author: Nazar65

dev/tests/integration/testsuite/Magento/Backend/Model/Dashboard/ChartTest.php

@@ -0,0 +1,81 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\Backend\Model;
+
+use Magento\Backend\Model\Dashboard\Chart;
+use Magento\TestFramework\Helper\Bootstrap;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Verify chart data by different period.
+ *
+ * @magentoAppArea adminhtml
+ */
+class ChartTest extends TestCase
+{
+    /**
+     * @var Chart
+     */
+    private $model;
+
+    /**
+     * @inheritdoc
+     */
+    protected function setUp()
+    {
+        $this->model = Bootstrap::getObjectManager()->create(Chart::class);
+    }
+
+    /**
+     * Verify getByPeriod with all types of period
+     *
+     * @magentoDataFixture Magento/Sales/_files/order_list_with_invoice.php
+     * @dataProvider getChartDataProvider
+     * @return void
+     */
+    public function testGetByPeriodWithParam(int $expectedDataQty, string $period, string $chartParam): void
+    {
+        $this->assertCount($expectedDataQty, $this->model->getByPeriod($period, $chartParam));
+    }
+
+    /**
+     * Expected chart data
+     *
+     * @return array
+     */
+    public function getChartDataProvider(): array
+    {
+        return [
+            [
+                24,
+                '24h',
+                'quantity'
+            ],
+            [
+                8,
+                '7d',
+                'quantity'
+            ],
+            [
+                6,
+                '1m',
+                'quantity'
+            ],
+            [
+                16,
+                '1y',
+                'quantity'
+            ],
+            [
+                28,
+                '2y',
+                'quantity'
+            ]
+        ];
+    }
+}