@Test
public void test_boolean_and_null() {

  FunctionExpression and =
      dsl.and(DSL.literal(LITERAL_TRUE), DSL.ref(BOOL_TYPE_NULL_VALUE_FIELD, BOOLEAN));
  assertEquals(BOOLEAN, and.type());
  assertEquals(LITERAL_NULL, and.valueOf(valueEnv()));
  and = dsl.and(DSL.ref(BOOL_TYPE_NULL_VALUE_FIELD, BOOLEAN), DSL.literal(LITERAL_TRUE));
  assertEquals(BOOLEAN, and.type());
  assertEquals(LITERAL_NULL, and.valueOf(valueEnv()));
  and = dsl.and(DSL.literal(LITERAL_FALSE), DSL.ref(BOOL_TYPE_NULL_VALUE_FIELD, BOOLEAN));
  assertEquals(BOOLEAN, and.type());
  assertEquals(LITERAL_FALSE, and.valueOf(valueEnv()));
  and = dsl.and(DSL.ref(BOOL_TYPE_NULL_VALUE_FIELD, BOOLEAN), DSL.literal(LITERAL_FALSE));
  assertEquals(BOOLEAN, and.type());
  assertEquals(LITERAL_FALSE, and.valueOf(valueEnv()));
}