PHPUnit assertStringStartsWith() Function

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

Syntax:

assertStringStartsWith(string $prefix, string $string
[, string $message = ''])

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

• $expectedprefix: This parameter is of any type which represents the expected prefix string.
• $actualstring: This parameter is of any type which represents the actual string.
• $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 assertStringStartsWith() function in PHPUnit:

Example 1:

PHP

<?php
use PHPUnit\Framework\TestCase;

class GeeksPhpunitTestCase extends TestCase
{
    public function testNegativeTestcaseForassertStringStartsWith()
    {
        $expectedprefix = ('dis');
        $actualstring = ('agreedis');

        // Assert function to test whether
        // actual string content starts with
        // expected prefix string content or not
        $this->assertStringStartsWith(
            $expectedprefix,
            $actualstring,
            "actual string content start with expected
             prefix content or not"
        );
    }
}

?>

Output:

PHPUnit 8.5.8 by Sebastian Bergmann and contributors.

F                                                         1 / 1 (100%)

Time: 89 ms, Memory: 10.00 MB

There was 1 failure:

1) GeeksPhpunitTestCase::testNegativeTestcaseForassertStringStartsWith
actual string content start with expected prefix content or not
Failed asserting that 'agreedis' starts with "dis".

/home/lovely/Documents/php/test.php:17

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

Example 2:

PHP

<?php
use PHPUnit\Framework\TestCase;

class GeeksPhpunitTestCase extends TestCase
{
    public function testPositiveTestcaseForassertStringStartsWith()
    {
        $expectedprefix = ('dis');
        $actualstring = ('disagree');

        // Assert function to test whether
        // actual string content starts with
        // expected prefix string content or not
        $this->assertStringStartsWith(
            $expectedprefix,
            $actualstring,
            "actual string content start with expected
             prefix content or not"
        );
    }
}

?>

Output:

PHPUnit 8.5.8 by Sebastian Bergmann and contributors.

.                                                 1 / 1 (100%)

Time: 88 ms, Memory: 10.00 MB

OK (1 test, 1 assertion)

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