ci_phpunit_test: Help needed about test double with queries - php

Question

i'm learning about unit testing with CodeIgniter and i would to ask some questions about testing queries with Mocks class.
I tried to implement the following class News_model with the method get_news_all() that returns all news data from table 'news' and get_news returns only title and text fields from the same.
class News_model extends CI_Model
{
public function __construct(){
$this->load->database();
}
public function get_news_all()
{
$query=$this->db->get('news');
$result=$query->result_array();
return $result;
}
public function get_news()
{
$this->db->select('title, text');
$this->db->from('news');
$query=$this->db->get();
$result=$query->result_array();
return $result;
}
After i tried to build a News_model_with_mocks_test for testing method get_news_all() and in this case test runs fine:
class News_model_with_mocks_test extends TestCase
{
public function setUp()
{
$this->resetInstance();
$loader=$this->getMockBuilder('CI_Loader')->setMethods(['database'])->getMock();
$loader->method('database')->willReturn($loader);
$this->CI->load=$loader;
if(!class_exists('CI_DB', false))
{
eval('class CI_DB extends CI_DB_query_builder {}');
}
$this->obj=new News_model();
}
public function test_1()
{
$result_array = [
[
"id" => "1",
"title" => "News",
"slug" => "news",
"text" => "News",
],
[
"id" => "2",
"title" => "News2",
"slug" => "news2",
"text" => "News2",
],
];
$db_result=$this->getMockBuilder('CI_DB_result')->disableOriginalConstructor()->getMock();
$db_result->method('result_array')->willReturn($result_array);
$db = $this->getMockBuilder('CI_DB')->disableOriginalConstructor()->getMock();
$db->expects($this->once())->method('get')->with('news')->willReturn($db_result);
$this->obj->db=$db;
$result=$this->obj->get_news_all();
$this->assertEquals($result_array,$result);
}
}
But i don't know how to do tests for the method get_news(), i tried something as this:
public function test_1()
{
$result_array2 = [
[
"title" => "News",
"text" => "News",
],
[
"title" => "News2",
"text" => "News2",
],
];
$db_result=$this->getMockBuilder('CI_DB_result')->disableOriginalConstructor()->getMock();
$db_result->method('result_array')->willReturn($result_array2);
$db = $this->getMockBuilder('CI_DB')->disableOriginalConstructor()->getMock();
$db->expects($this->once())->method('query')->with('select title,text from news')->willReturn($db_result);
$this->obj->db=$db;
$result=$this->obj->get_news();
$this->assertEquals($result_array2,$result);
}
phpunit thows the following exception:
PHP Fatal error: Call to a member function result_array() on a non- object in /opt/lampp/htdocs/codeigniter/application/models/Users_model.php on line 21
I don't know how to test double with select queries! Thank you in advance for your answers.

Answer 1

i read more documentation in these days and i understood that it was a misunderstanding for me about usage of Mocks. In other words we have to define methods and returning values that we will expect and inject them to original classes. This is the method get_users of the class News_model that i wrote above:
public function get_news()
{
$this->db->select('title, text');
$this->db->from('news');
$query=$this->db->get();
$result=$query->result_array();
return $result;
}
We simply want that the get() method will return a result array which contains only title and text fields for each record:
class News_model_with_mocks_test extends TestCase
{
public function setUp()
{
$this->resetInstance();
$loader=$this->getMockBuilder('CI_Loader')->setMethods(['database'])->getMock();
$loader->method('database')->willReturn($loader);
$this->CI->load=$loader;
if(!class_exists('CI_DB', false))
{
eval('class CI_DB extends CI_DB_query_builder {}');
}
$this->obj=new News_model();
}
public function test_1()
{
$result_array = [
[
"title" => "News test",
"text" => "News text",
],
[
"title" => "News2",
"text" => "Testo news2",
],
];
$db_result=$this->getMockBuilder('CI_DB_result')->disableOriginalConstructor()->getMock();
$db_result->method('result_array')->willReturn($result_array);
$db = $this->getMockBuilder('CI_DB')->disableOriginalConstructor()->getMock();
$db->expects($this->once())->method('get')->willReturn($db_result);
$this->obj->db=$db;
$result=$this->obj->get_news();
$this->assertEquals($result_array,$result);
}
}
I hope that this solution could help someone that could have same doubts!