silverstripe-framework/tests/php/Forms/TreeMultiselectFieldTest.php

<?php

namespace SilverStripe\Forms\Tests;

use SilverStripe\Assets\File;
use SilverStripe\Dev\SapphireTest;
use SilverStripe\Forms\TreeMultiselectField;

class TreeMultiselectFieldTest extends SapphireTest
{
    protected static $fixture_file = 'TreeDropdownFieldTest.yml';

    public function testReadonly()
    {
        $field = new TreeMultiselectField('TestTree', 'Test tree', File::class);
        $asdf = $this->objFromFixture(File::class, 'asdf');
        $subfolderfile1 = $this->objFromFixture(File::class, 'subfolderfile1');
        $field->setValue(implode(',', [$asdf->ID, $subfolderfile1->ID]));

        $readonlyField = $field->performReadonlyTransformation();
        $this->assertEquals(
            <<<"HTML"
<span id="TestTree_ReadonlyValue" class="readonly">
	&lt;Special &amp; characters&gt;, TestFile1InSubfolder
</span><input type="hidden" name="TestTree" value="{$asdf->ID},{$subfolderfile1->ID}" class="hidden" id="TestTree" />
HTML
            ,
            (string)$readonlyField->Field()
        );
    }
}