Test methods fail using Storage. Illuminate\Http\Testing\imagepng() in Laravel

Hello, I'm doing TDD to test my development, my tests were passing until I decided to reinstall php to repair the sqlite driver for testing (the main driver is mysql). So when I run my hole suite of tests this error shows in every method that uses the storage:

Error : Call to undefined function Illuminate\Http\Testing\imagepng()
 {laravel}/framework/src/Illuminate/Http/Testing/FileFactory.php:46
 {laravel}/framework/src/Illuminate/Support/helpers.php:1038
 {laravel}/framework/src/Illuminate/Http/Testing/FileFactory.php:49
 {laravel}/framework/src/Illuminate/Http/Testing/FileFactory.php:31
 {laravel}/tests/Feature/FacilityTest.php:38

This one is a method that throws the above error (the line 38 is signaled):

/**
 * @test
 * Test for: a Facility can be registered by an admin.
 */
public function a_facility_can_be_registered_by_an_admin()
{
    /** Given a correct information for a facility */
    \Storage::fake('public');

   // Next line is 38 the problematic one:
    $data = ["name" => "Facility A", 'image' => UploadedFile::fake()->image('facility-a.jpg')];

    /** When the request is made by an admin */
    $admin = $this->createUser([], 'admin');
    $response = $this->apiAs($admin, 'POST', '/api/v1/manage/facilities', $data);

    /** Then the facility should be registered */
    $response->assertStatus(Response::HTTP_CREATED);
}

I really don't know why.

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If this helps, this is my phpunit file:

phpunit.xml

<?xml version="1.0" encoding="UTF-8"?>
<phpunit backupGlobals="false"
         backupStaticAttributes="false"
         bootstrap="vendor/autoload.php"
         colors="true"
         convertErrorsToExceptions="true"
         convertNoticesToExceptions="true"
         convertWarningsToExceptions="true"
         processIsolation="false"
         stopOnFailure="false">
    <testsuites>
        <testsuite name="Feature">
            <directory suffix="Test.php">./tests/Feature</directory>
        </testsuite>

        <testsuite name="Unit">
            <directory suffix="Test.php">./tests/Unit</directory>
        </testsuite>
    </testsuites>
    <filter>
        <whitelist processUncoveredFilesFromWhitelist="true">
            <directory suffix=".php">./app</directory>
        </whitelist>
    </filter>
    <php>
        <env name="APP_ENV" value="testing"/>
        <env name="CACHE_DRIVER" value="array"/>
        <env name="SESSION_DRIVER" value="array"/>
        <env name="QUEUE_DRIVER" value="sync"/>
        <env name="DB_CONNECTION" value="sqlite"/>
    </php>
</phpunit>

---

Thanks in advance.

via Chebli Mohamed