@Test
public void test_null_xor_missing() {

  FunctionExpression xor = dsl.xor(DSL.ref(BOOL_TYPE_MISSING_VALUE_FIELD, BOOLEAN),
      DSL.ref(BOOL_TYPE_MISSING_VALUE_FIELD, BOOLEAN));
  assertEquals(BOOLEAN, xor.type());
  assertEquals(LITERAL_MISSING, xor.valueOf(valueEnv()));
  xor = dsl.xor(DSL.ref(BOOL_TYPE_NULL_VALUE_FIELD, BOOLEAN),
      DSL.ref(BOOL_TYPE_NULL_VALUE_FIELD, BOOLEAN));
  assertEquals(BOOLEAN, xor.type());
  assertEquals(LITERAL_NULL, xor.valueOf(valueEnv()));
  xor = dsl.xor(DSL.ref(BOOL_TYPE_NULL_VALUE_FIELD, BOOLEAN),
      DSL.ref(BOOL_TYPE_MISSING_VALUE_FIELD, BOOLEAN));
  assertEquals(BOOLEAN, xor.type());
  assertEquals(LITERAL_NULL, xor.valueOf(valueEnv()));
  xor = dsl.xor(DSL.ref(BOOL_TYPE_MISSING_VALUE_FIELD, BOOLEAN),
      DSL.ref(BOOL_TYPE_NULL_VALUE_FIELD, BOOLEAN));
  assertEquals(BOOLEAN, xor.type());
  assertEquals(LITERAL_NULL, xor.valueOf(valueEnv()));
}