setOption() public method

You can pass an $option name to set to $value, an array of $option names to set to $value, or an associative array of $option names and their values to set.
public setOption ( string | array $option, boolean | integer | null $value = null )
$option string | array String or array of strings or associative array of keys of option names to set $value to
$value boolean | integer | null Boolean, integer or null $value to set $option to (optional)
 public function testSettingAndUnsettingOptions()
 {
     $this->sandbox->setOption('error_level', 1);
     $this->assertEquals(1, $this->sandbox->getOption('error_level'));
     $this->sandbox->setOption('error_level', null);
     $this->assertEquals(null, $this->sandbox->getOption('error_level'));
 }