PHPUnit cannot mock __get function on mock object - php

Question

I am trying to mock a mysqli object for my unit testing and therefore I have to either mock the property mysqli_result::__get() or mock the property mysqli_result::num_rows directly.
I already looked for a solution but the answers I found were just not working.
My Code looks like this:
use PHPUnit\Framework\TestCase;
class Mocks extends TestCase{
public function makeMysqliMock(array $queries): mysqli{
// build mocked mysqli-object
#$link = $this
# ->getMockBuilder("mysqli")
# // set methods
# ->setMethods(['__get', "query", "real_escape_string"])
# ->getMock();
$link = $this->createMock("mysqli");
// set method 'real_escape_string'
$link->expects($this->any())
->method("real_escape_string")
->will($this->returnCallback(function($str){
return addslashes($str);
}));
// set method 'query'
$link->expects($this->any())
->method("query")
->will($this->returnCallback(function(string $query) use ($queries){
// pick the query result for the current test
$data = isset($queries[$query]) ? $queries[$query] : null;
// build mocked 'mysqli_result'
if (is_array($data)){
$result = $this
->getMockBuilder("mysqli_result")
->setMethods(["fetch_assoc", "__get"])
->disableOriginalConstructor()
->getMock();
// build simulated fetch method
$result->expects($this->any())
->method("fetch_assoc")
->withAnyParameters()
->will($this->returnCallback(function() use ($data){
// set internal result pointer
static $index = 0;
// return current result - increment pointer
return isset($data[$index]) ? $data[$index++] : false;
}));
$result->expects($this->at(0))
->method("__get")
->with($this->equalTo("mysqli_num_rows"))
->will($this->returnValue(count($data)));
return $result;
}else {
return is_null($data) ? false : 1;
}
}));
return $link;
}
}
When I run that code phpunit gives me the following error message:
C:\xampp\htdocs\werimanage\php>php phpunit-6.0.11.phar tests
PHPUnit 6.0.11 by Sebastian Bergmann and contributors.
PHP Fatal error: Method Mock_mysqli_result_d3aa5482::__get() must take exactly 1 argument in phar://C:/xampp/htdocs/werimanage/php/phpunit-6.0.11.phar/phpunit-mock-objects/Generator.php(263) : eval()'d code on line 53
Fatal error: Method Mock_mysqli_result_d3aa5482::__get() must take exactly 1 argument in phar://C:/xampp/htdocs/werimanage/php/phpunit-6.0.11.phar/phpunit-mock-objects/Generator.php(263) : eval()'d code on line 53
So I do not know what the error is or how to fix it. I would really appreciate your help. Thanks!

Answer 1

according to the php documentation the method __get requires 1 argument (more over this is the error phpUnit is returning).
You can see on the documentation :
public mixed __get ( string $name )
The $name argument is the name of
the property being interacted with.
I imagine that you will be calling the __get method foreach of your column in your sql request. You then have to mock all the calls and the returns of the __get method with each argument (each column).
Hope this will help you.

Answer 2

This error happens because magic method __get must accept one parameter -- the name of the property. When PHPUnit generates the code to declare the mock it uses the declaration of the method from the original class. Since there is no method __get declared for mysqli_result PHPUnit mock generator declares it as __get() without parameters, and this is encountered as error.
If you really want to do your coding and testing the way you do it, you can use the following approach:
class SuperMock extends mysqli_result {
public function __get($name){
}
}
class Mocks extends PHPUnit_Framework_TestCase
{
public function testGet()
{
$data = ['one' => 1, 'two' => 2];
$mock = $this->getMockBuilder('SuperMock')
->disableOriginalConstructor()
->setMethods(['__get', 'fetch_assoc'])
->getMock();
$mock->expects($this->once())
->method('__get')
->with('nonexistent')
->willReturn(42);
$mock->expects($this->once())
->method('fetch_assoc')
->willReturn($data);
$this->assertInstanceOf('mysqli_result', $mock);
$this->assertSame(42, $mock->nonexistent);
$this->assertSame($data, $mock->fetch_assoc());
}
public function testDirectProperty(){
$mock = $this->getMockBuilder('SuperMock')
->disableOriginalConstructor()
->setMethods(['__get', 'fetch_assoc'])
->getMock();
$mock->nonexistent = 42;
$this->assertSame(42, $mock->nonexistent);
}
}
This will technically solve the issue. Still I would suggest revising your testing strategy. Because now it looks like you are testing how the interaction with a database is performed. But do you really need to test if data is fetched as an associative array, and that number of rows is figured out through mysqli_num_rows property? Going this way makes tests too much coupled to the production code. I believe this is the case when it is more suffucient to test the result being retrieved rather than the internal details of this process.