don't use phpunit's assertEquals to compare closures.

ClosureComparisonTest.php

<?php

class ClosureCompraisonTest extends PHPUnit_Framework_TestCase
{
    // passes. WTF???
    public function test_assertEquals()
    {
        $f1 = function () { return 1; };
        $f2 = function () { return 2; };
        $this->assertEquals($f1, $f2);
    }

    // fails, don't kid me
    public function test_assertNotEquals()
    {
        $f1 = function () { return 1; };
        $f2 = function () { return 2; };
        $this->assertNotEquals($f1, $f2);
    }

    // fails, of course
    public function test_assertSame()
    {
        $f1 = function () { return 1; };
        $f2 = function () { return 2; };
        $this->assertSame($f1, $f2);
    }

    // passes
    public function test_assertNotSame()
    {
        $f1 = function () { return 1; };
        $f2 = function () { return 2; };
        $this->assertNotSame($f1, $f2);
    }

    // passes
    public function test_doubleEqual()
    {
        $f1 = function () { return 1; };
        $f2 = function () { return 2; };
        $this->assertFalse($f1 == $f2);
    }

    // passes
    public function test_tripleEqual()
    {
        $f1 = function () { return 1; };
        $f2 = function () { return 2; };
        $this->assertFalse($f1 === $f2);
    }
}

gistfile1.txt

% ./vendor/phpunit/phpunit/phpunit.php ClosureComparisonTest.php
PHPUnit 3.7.27 by Sebastian Bergmann.

Configuration read from /Users/atsushi/prog/phpmethodreplacer/phpunit.xml.dist

.FF...

Time: 63 ms, Memory: 2.75Mb

There were 2 failures:

1) ClosureCompraisonTest::test_assertNotEquals
Failed asserting that Closure Object (
    0 => Closure Object (*RECURSION*)
) is not equal to Closure Object (
    0 => Closure Object (*RECURSION*)
).

/Users/atsushi/prog/phpmethodreplacer/ClosureComparisonTest.php:18

2) ClosureCompraisonTest::test_assertSame
Failed asserting that two variables reference the same object.

/Users/atsushi/prog/phpmethodreplacer/ClosureComparisonTest.php:26

FAILURES!
Tests: 6, Assertions: 6, Failures: 2.