@Test
 public void testEqualsOnNonExistingKey() {
   assertFalse(Predicatr.parse("true & com.foo#bar?", variables));
 }
 @Test
 public void testEquals() {
   assertTrue(Predicatr.parse("true & com.acme#foobar?", variables));
 }
 @Test
 public void testNotEquals() {
   assertFalse(Predicatr.parse("! com.acme#foobar?", variables));
 }
 @Test
 public void testExistence() {
   assertTrue(Predicatr.parse("true & com.platzhaltr?", variables));
 }
 @Test
 public void testNotExistence() {
   assertFalse(Predicatr.parse("!com.platzhaltr?", variables));
 }
 @Test
 public void testDotInName() {
   assertTrue(Predicatr.parse("true & com.platzhaltr", variables));
 }
 @Test
 public void testVariableWithNot() {
   assertTrue(Predicatr.parse("!no & true", variables));
 }
 @Test
 public void testMultipleVariable() {
   assertTrue(Predicatr.parse("yes | no", variables));
 }
 @Test
 public void testSingleVariable() {
   assertTrue(Predicatr.parse("true & yes", variables));
   assertTrue(Predicatr.parse("true | yes", variables));
 }
 @Test
 public void testUnusedVariables() {
   assertTrue(Predicatr.parse("true | false", variables));
 }