assertNan()

<?php
use PHPUnit\Framework\TestCase;

class NanTest extends TestCase
{
    public function testFailure()
    {
        $this->assertNan(1);
    }
}
?>

phpunit NanTest
PHPUnit 5.6.0 by Sebastian Bergmann and contributors.

F

Time: 0 seconds, Memory: 5.00Mb

There was 1 failure:

1) NanTest::testFailure
Failed asserting that 1 is nan.

/home/sb/NanTest.php:6

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