TypeError, function() { node.substringData() })
    assert_throws_js(TypeError, function() { node.substringData(0) })
  }, type + ".substringData() with too few arguments")

  test(function() {
    var node = create()
    assert_equals(node.data, "test")

    assert_equals(node.substringData(0, 1, "test"), "t")
  }, type + ".substringData() with too many arguments")

  test(function() {
    var node = create()
    assert_equals(node.data, "test")

    assert_throws_dom("IndexSizeError", function() { node.su