ingle3.matches(":checked"), "single3 not :checked");

  single1.checked = true;
  assert_true(single1.checked, "single1 IS checked [after single1 checked]");
  assert_true(single1.matches(":checked"),
      "single1 IS :checked [after single1 checked]");
  assert_false(single2.checked, "single2 not checked [after single1 checked]");
  assert_false(single2.matches(":checked"),
      "single2 not :checked [after single1 checked]");
  assert_false(single3.checked, "single3 not checked [after single1 checked]")