The exhaustive tests are in test/controller/html/sanitizer_test.rb. This tests that the helpers hook up correctly to the sanitizer classes.

Methods
T
Instance Public methods
test_sanitize_form()
# File actionview/test/template/sanitize_helper_test.rb, line 15
def test_sanitize_form
  assert_equal '', sanitize("<form action=\"/foo/bar\" method=\"post\"><input></form>")
end
test_sanitize_is_marked_safe()
# File actionview/test/template/sanitize_helper_test.rb, line 36
def test_sanitize_is_marked_safe
  assert sanitize("<html><script></script></html>").html_safe?
end
test_should_sanitize_illegal_style_properties()
# File actionview/test/template/sanitize_helper_test.rb, line 19
def test_should_sanitize_illegal_style_properties
  raw      = %Q(display:block; position:absolute; left:0; top:0; width:100%; height:100%; z-index:1; background-color:black; background-image:url(http://www.ragingplatypus.com/i/cam-full.jpg); background-x:center; background-y:center; background-repeat:repeat;)
  expected = %Q(display: block; width: 100%; height: 100%; background-color: black; background-x: center; background-y: center;)
  assert_equal expected, sanitize_css(raw)
end
test_strip_tags()
# File actionview/test/template/sanitize_helper_test.rb, line 25
def test_strip_tags
  assert_equal("Dont touch me", strip_tags("Dont touch me"))
  assert_equal("This is a test.", strip_tags("<p>This <u>is<u> a <a href='test.html'><strong>test</strong></a>.</p>"))
  assert_equal "This has a  here.", strip_tags("This has a <!-- comment --> here.")
  assert_equal "", strip_tags("<script>")
end
test_strip_tags_will_not_encode_special_characters()
# File actionview/test/template/sanitize_helper_test.rb, line 32
def test_strip_tags_will_not_encode_special_characters
  assert_equal "test\r\n\r\ntest", strip_tags("test\r\n\r\ntest")
end