PHPUnit assertFileIsWritable() Function

The assertFileIsWritable() function is a builtin function in PHPUnit and is used to assert whether the file specified is a file is writable or not. This assertion will return true in the case if either given filename exists and is writable else return false. In case of true the asserted test case got passed else test case got failed.

Syntax:

assertFileIsWritable(string $filename[, string $message = ''])

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

• $filename: This parameter is a string that denotes the file name.
• $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 assertFileIsWritable() function in PHPUnit:

Example 1:

<?php 
use PHPUnit\Framework\TestCase; 
  
class GeeksPhpunitTestCase extends TestCase 
{ 
    public function testNegativeTestcaseForassertFileIsWritable() 
    { 
        $filename = "/home/lovely/Documents/phptest"; 
  
        // Assert function to test whether given 
        // file name exists and readable 
        $this->assertFileIsWritable( 
            $filename, 
            "filename exists and writable"
        ); 
    } 
} 
  
?> 

Output:

PHPUnit 8.5.8 by Sebastian Bergmann and contributors.

F                                                 1 / 1 (100%)

Time: 90 ms, Memory: 10.00 MB

There was 1 failure:

1) GeeksPhpunitTestCase::testNegativeTestcaseForassertFileIsWritable
filename exists and writable
Failed asserting that file "/home/lovely/Documents/phptest" exists.

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

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

Example 2:

<?php 
use PHPUnit\Framework\TestCase; 
  
class GeeksPhpunitTestCase extends TestCase 
{ 
    public function testPositiveTestcaseForassertFileIsWritable() 
    { 
        $filename = "/home/lovely/Documents"; 
  
        // Assert function to test whether given 
        // file name exists and readable 
        $this->assertFileIsWritable( 
            $filename, 
            "filename exists and writable"
        ); 
    } 
} 
  
?> 

Output:

PHPUnit 8.5.8 by Sebastian Bergmann and contributors.

.                                       1 / 1 (100%)

Time: 94 ms, Memory: 10.00 MB

OK (1 test, 2 assertions)