assertStringNotEqualsFile example

$this->assertFileExists($this->secretsDir.'/test.encrypt.public.php');
        $this->assertFileExists($this->secretsDir.'/test.decrypt.private.php');

        $encKey = file_get_contents($this->secretsDir.'/test.encrypt.public.php');
        $decKey = file_get_contents($this->secretsDir.'/test.decrypt.private.php');

        $this->assertFalse($vault->generateKeys());
        $this->assertStringEqualsFile($this->secretsDir.'/test.encrypt.public.php', $encKey);
        $this->assertStringEqualsFile($this->secretsDir.'/test.decrypt.private.php', $decKey);

        $this->assertTrue($vault->generateKeys(true));
        $this->assertStringNotEqualsFile($this->secretsDir.'/test.encrypt.public.php', $encKey);
        $this->assertStringNotEqualsFile($this->secretsDir.'/test.decrypt.private.php', $decKey);
    }

    public function testEncryptAndDecrypt()
    {
        $vault = new SodiumVault($this->secretsDir);
        $vault->generateKeys();

        $plain = "plain\ntext";

        $vault->seal('foo', $plain);