PHPUnit assertIsString() Function

The assertIsstring() function is a builtin function in PHPUnit and is used to assert whether the actually obtained value is a string value or not. This assertion will return true in the case if the actual value is string else returns false. In case of true the asserted test case got passed else test case got failed.

Syntax:

assertIsString($actual[, $message = ''])

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

• $actualvalue: This parameter is of any type which represents the actual data.
• $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 assertIsString() function in PHPUnit:

Example 1:

PHP

<?php
use PHPUnit\Framework\TestCase;

class GeeksPhpunitTestCase extends TestCase
{
    public function testNegativeTestcaseForassertIsString()
    {
        $actualvalue = 44;

        // Assert function to test whether given
        // actual value is a string or not
        $this->assertIsString(
          $actualvalue,
          "actual value is a string or not"
        );
    }
}

?>

Output:

PHPUnit 8.5.8 by Sebastian Bergmann and contributors.

F                                                 1 / 1 (100%)

Time: 117 ms, Memory: 10.00 MB

There was 1 failure:

1) GeeksPhpunitTestCase::testNegativeTestcaseForassertIsString
actual value is a string or not
Failed asserting that 220 is of type "string".

/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 testPositiveTestcaseForassertIsString()
    {
        $actualvalue = "420";

        // Assert function to test whether given
        // actual value is a string or not
        $this->assertIsString(
          $actualvalue,
          "actual value is a string 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#assertisstring