@Test
 public void testInvalid() {
   assertNull(screamer.getParameter(6));
 }
 @Test
 public void testLevel() {
   assertEquals("dB", screamer.getParameter(5).getUnit());
 }
 @Test
 public void testDrive() {
   assertEquals("", screamer.getParameter(3).getUnit());
 }
 @Test
 public void testTone() {
   assertEquals("", screamer.getParameter(4).getUnit());
 }
 @Test
 public void testHi() {
   assertEquals("dB", screamer.getParameter(2).getUnit());
 }