How to write unit test for get country name by code?

Question

I wrote a prepareDataSource function and unit test for that function as below. When I run test function it throw error: Error : Call to a member function loadByCode() on null Please help me how to fix it?

prepareDataSource function as below:

namespace MyApp\SaleReports\Ui\Component\Listing\Columns\CountryReport;

class CountryName extends \MyApp\SaleReports\Ui\Component\Listing\Columns\BaseColumn
{
    /**
     * Prepare Data Source
     *
     * @param array $dataSource
     * @return array
     */
    public function prepareDataSource(array $dataSource)
    {
        if (isset($dataSource['data']['items'])) {
            $fieldName = $this->getData('name');
            foreach ($dataSource['data']['items'] as & $item) {
                $country_id = $item['country_id'];
                $country = $this->_countryFactory->create()->**loadByCode**($country_id);
                $item[$fieldName] = $country->getName();
            }
        }

        return $dataSource;
    }
}

So I write unit test for this function as below:

<?php


namespace MyApp\SaleReports\Test\Unit\Ui\Component\Listing\Comlumns\CountryReport;

use Magento\Framework\TestFramework\Unit\Helper\ObjectManager;
use MyApp\SaleReports\Ui\Component\Listing\Columns\CountryReport\CountryName;
class CountryNameTest extends \PHPUnit\Framework\TestCase
{
    protected $_model;
    protected $_country;

    public function setUp()
    {
        $objectManager = new ObjectManager($this);
        $contextMock = $this->getMockBuilder(\Magento\Framework\View\Element\UiComponent\ContextInterface::class)
            ->getMockForAbstractClass();
        $processor = $this->getMockBuilder(\Magento\Framework\View\Element\UiComponent\Processor::class)
            ->disableOriginalConstructor()
            ->getMock();
        $contextMock->expects($this->never())
            ->method('getProcessor')
            ->willReturn($processor);
        $this->_country = $this->getMockBuilder(\Magento\Directory\Model\Country::class)
            ->disableOriginalConstructor()
            ->getMock();
        $this->_model = $objectManager->getObject(
            CountryName::class,
            [
                '_country' => $this->_country,
                'context' => $contextMock
            ]
        );
    }

    public function testPrepareDataSource()
    {
        $country_id = 'US';
        $itemName = "itemName";
        $oldItemValue = "oldItemValue";
        $expectDeliveryName = "United States";

        $dataSource = [
            'data' => [
                'items' => [
                    [
                        "country_id" => $country_id,
                        $itemName => $oldItemValue
                    ]
                ]
            ]
        ];



        $this->_model->setData('name', $itemName);
        $dataSource = $this->_model->prepareDataSource($dataSource);
        $this->assertEquals($expectDeliveryName, $dataSource['data']['items'][0][$itemName]);
    }
}

The BaseColumn class as below:

<?php


namespace MyApp\SaleReports\Ui\Component\Listing\Columns;

use Magento\Framework\View\Element\UiComponentFactory;
use Magento\Framework\View\Element\UiComponent\ContextInterface;
use Magento\Framework\Pricing\PriceCurrencyInterface;
use Magento\Directory\Model\CountryFactory;
use Magento\Store\Model\StoreManagerInterface;
use Magento\Directory\Model\CurrencyFactory;

class BaseColumn extends \Magento\Ui\Component\Listing\Columns\Column
{

    /**
     * Column name
     */
    const NAME = 'name';
    private $_report;
    /**
     * @var StoreManagerInterface
     */
    private $_storeManager;

    /**
     * @var CurrencyFactory
     */
    private $_currency;
    protected $_priceCurrency;
    protected $_countryFactory;

    protected $_storeResolver;

    public function __construct(
        ContextInterface $context,
        UiComponentFactory $uiComponentFactory,
        \MyApp\SaleReports\Model\Report $report,
        PriceCurrencyInterface $priceCurrency,
        CountryFactory $countryFactory,
        StoreManagerInterface $storeManager,
        CurrencyFactory $currencyFactory,
        \Magento\Store\Model\StoreResolver $storeResolver,
        array $components = [],
        array $data = []
    ) {
        parent::__construct($context, $uiComponentFactory, $components, $data);
        $this->_report = $report;
        $this->_priceCurrency = $priceCurrency;
        $this->_countryFactory = $countryFactory;
        $this->_storeManager = $storeManager;
        $this->_currency = $currencyFactory->create();
        $this->_storeResolver = $storeResolver;
    }

    /**
     * @return StoreInterface
     * @throws NoSuchEntityException
     */
    protected function getStore()
    {
        $currentStore = $this->_storeResolver->getCurrentStoreId();
        return $this->_storeManager->getStore($currentStore);
    }

    /**
     * Convert money by currency
     * @param $money_value
     * @return float
     * @throws NoSuchEntityException
     */
    protected function convertMoney($money_value)
    {
        $currencyCode = $this->getStore()->getCurrentCurrencyCode();
        return $this->_priceCurrency->convert($money_value, $this->getStore(), $currencyCode);
    }

    protected function getCurrency($currencyCode)
    {
        return $this->_currency->load($currencyCode);
    }

    /**
     * Get store base currency code
     *
     * @return string
     */
    public function getBaseCurrencyCode()
    {
        return $this->_storeManager->getStore()->getBaseCurrencyCode();
    }
}

Thank you so much, BienHV

Answer 1

Most (as far as I can tell) mocks do not return anything. If you call a method on a mock, it will return null. These errors usually turns up when method calls are chained: $this->_countryFactory->create()->loadByCode($country_id). Basically the call to create of the _countryFactory mock returns null; you can't call loadByCode on null.

The process is to mock the factory's create method to return something. Sample untested code:

$countryFactoryMock = $this->createMock(\Magento\Directory\Model\CountryFactory:class);
$country = $objectManager->getObject(Country:class, []);
$countryFactoryMock->method('create')->willReturn($country);

Also, I didn't look at the country model, but I believe loadByCode calls the database; more mocking may be necessary.