asort.php

<?php

class NameValuePair
{
    /** @var string */
    private $name;

    /** @var mixed */
    private $value;

    /**
     * NameValuePair constructor.
     *
     * @param string $name
     * @param mixed $value
     */
    public function __construct($name, $value)
    {
        $this->name = $name;
        $this->value = $value;
    }

    /**
     * @return string
     */
    public function getName()
    {
        return $this->name;
    }

    /**
     * @return mixed
     */
    public function getValue()
    {
        return $this->value;
    }
}

/**
 * Class ASortObjectTest
 *
 * bin/phpunit -c app/phpunit.xml --stderr --filter ASortObjectTest
 */
class ASortObjectTest extends PHPUnit_Framework_TestCase
{
    /** @var NameValuePair[] */
    private $nameValuePairs;

    /** @var array */
    const EXPECTED_SORTED_VALUES = [
        'a',
        'b',
        'c',
        'd',
        'e',
        'f',
        'g',
        'h',
        'i',
        'j',
        'k',
        'l',
        'm',
        'n',
        'o',
        'p',
        'q',
        'r',
        's'
    ];

    public function setUp()
    {
        $this->nameValuePairs = [
            new NameValuePair('l', 'l'),
            new NameValuePair('b', 'b'),
            new NameValuePair('k', 'k'),
            new NameValuePair('c', 'c'),
            new NameValuePair('o', 'o'),
            new NameValuePair('e', 'e'),
            new NameValuePair('m', 'm'),
            new NameValuePair('q', 'q'),
            new NameValuePair('f', 'f'),
            new NameValuePair('g', 'g'),
            new NameValuePair('p', 'p'),
            new NameValuePair('d', 'd'),
            new NameValuePair('h', 'h'),
            new NameValuePair('i', 'i'),
            new NameValuePair('j', 'j'),
            new NameValuePair('s', 's'),
            new NameValuePair('n', 'n'),
            new NameValuePair('r', 'r'),
            new NameValuePair('a', 'a'),
        ];
    }

    public function testAsortOnNameValuePairInstances()
    {
        asort($this->nameValuePairs);
        $sortedValues = array_map(function (NameValuePair $nameValuePair) {
            return $nameValuePair->getValue();
        }, $this->nameValuePairs);

        $this->assertSame(
            array_values(self::EXPECTED_SORTED_VALUES),
            array_values($sortedValues)
        );
    }

    public function testUasortOnNameValuePairInstances()
    {
        uasort($this->nameValuePairs, function (NameValuePair $left, NameValuePair $right) {
            return strcmp($left->getName(), $right->getName());
        });

        $sortedValues = array_map(function (NameValuePair $nameValuePair) {
            return $nameValuePair->getValue();
        }, $this->nameValuePairs);

        $this->assertSame(
            array_values(self::EXPECTED_SORTED_VALUES),
            array_values($sortedValues)
        );
    }
}

PHPUnit 5.7.27 by Sebastian Bergmann and contributors.

.. 2 / 2 (100%)

Time: 2.75 seconds, Memory: 146.00MB

OK (2 tests, 2 assertions)

• Can't find any documentation online about how PHP treats objects within in an array when performing an asort
• Would have thought the default behaviour would be something along the lines of spl_object_hash and a sort on the hashes
• Appears to sort using the $name property of the NameValuePair instance, not the $value
• Is PHP doing something like get_object_vars() to get the object as an array and then sorting on that? get_object_vars would return an empty array on private properties though
• How is PHP getting to the $name attribute? Why is it picking the $name attribute?
• Is something else at play here?