PHPUnit assertNan() Function

The assertNan() function is a builtin function in PHPUnit and is used to assert whether the variable is NAN or not. This assertion will return true in the case if the variable is NAN else returns false. In case of true the asserted test case got passed else test case got failed.

Syntax:

assertNan(mixed $variable[, string $message = ''])

Parameters: This function accepts two parameters as mentioned above and described below:

• $Variable: This parameter represents any type of variable.
• $message: This parameter takes a string value. When the test case got failed this string message got displayed as an error message.

Below examples illustrate the assertNan() function in PHPUnit:

Example 1:

PHP

<?php
use PHPUnit\Framework\TestCase;

class GeeksPhpunitTestCase extends TestCase
{
    public function testNegativeTestcaseForassertNan()
    {
        $variable = 0*0;

        // Assert function to test whether given
        // variable is (NAN) or not
        $this->assertNan(
          $variable,
          "variable is (NAN) or not"
        );
    }
}

?>

Output:

PHPUnit 8.5.8 by Sebastian Bergmann and contributors.

F                                                  1 / 1 (100%)

Time: 88 ms, Memory: 10.00 MB

There was 1 failure:

1) GeeksPhpunitTestCase::testNegativeTestcaseForassertNan
variable is (NAN) or not
Failed asserting that 0 is nan.

/home/lovely/Documents/php/test.php:15

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

Example 2:

PHP

<?php
use PHPUnit\Framework\TestCase;

class GeeksPhpunitTestCase extends TestCase
{
    public function testPositiveTestcaseForassertNan()
    {
        $variable = NAN;

        // Assert function to test whether given
        // variable is (NAN) or not
        $this->assertNan(
          $variable,
          "variable is (NAN) or not"
        );
    }
}

?>

Output:

PHPUnit 8.5.8 by Sebastian Bergmann and contributors.

.                                                  1 / 1 (100%)

Time: 87 ms, Memory: 10.00 MB

OK (1 test, 1 assertion)

Reference:https://phpunit.readthedocs.io/en/9.2/assertions.html#assertnan