chromium/third_party/blink/web_tests/editing/pasteboard/paste-as-plaintext-only-has-text-expected.txt

To run this test manually, simply try invoking the copy command on this page followed by the paste as plain text command. If it works, text/plain should be the only MIME type, 'Hello' should be associated with text/plain, and the empty string should be associated with text/html.
Types: text/plain
text/plain: "Hello"
text/html: ""