Tests writing with one class and reading with another.
function testReadOnly() {
$php = $this->storageFactory
->get('simpletest');
$name = $this
->randomName() . '/' . $this
->randomName() . '.php';
// Find a global that doesn't exist.
do {
$random = mt_rand(10000, 100000);
} while (isset($GLOBALS[$random]));
// Write out a PHP file and ensure it's successfully loaded.
$code = "<?php\n\$GLOBALS[{$random}] = TRUE;";
$success = $php
->save($name, $code);
$this
->assertSame($success, TRUE);
$php_read = $this->storageFactory
->get('readonly');
$php_read
->load($name);
$this
->assertTrue($GLOBALS[$random]);
// If the file was successfully loaded, it must also exist, but ensure the
// exists() method returns that correctly.
$this
->assertSame($php_read
->exists($name), TRUE);
// Saving and deleting should always fail.
$this
->assertFalse($php_read
->save($name, $code));
$this
->assertFalse($php_read
->delete($name));
}