phpunit assertion gotcha

phpunitAssertionsTest.php

<?php

class myClass
{
    public function __toString()
    {
        return "mememe";
    }
}

class TestCase extends PHPUnit_Framework_TestCase
{
    public function testAssertStringWithObject()
    {
        $class = new myClass();
        $this->assertEquals('mememe', $class);
    }

    public function testAssertStringWithSerialisedObject()
    {
        $class = new myClass();
        $this->assertEquals('mememe', "$class");
    }
}

$ phpunit testCaseTest.php
PHPUnit 3.5.15 by Sebastian Bergmann.

F.

Time: 1 second, Memory: 4.50Mb

There was 1 failure:

1) TestCase::testAssertStringWithObject
Failed asserting that 
myClass Object
(
)
 matches expected <string:mememe>.

/private/tmp/Testing/testCaseTest.php:16

FAILURES!
Tests: 2, Assertions: 2, Failures: 1.

$ phpunit testCaseTest.php 
PHPUnit 3.6.10 by Sebastian Bergmann.

..

Time: 1 second, Memory: 5.50Mb

OK (2 tests, 2 assertions)