This test verifies that, after reversion panel is shown, typing whitespace will dismiss the reversion panel.
After seeing the reversion panel, type whitespace. You should see the panel being dismissed once you start typing.
Note, this test can fail due to user specific spell checking data. If the user has previously frequently revert 'message' to 'mesage'. To fix this, remove all files in ~/Library/Spelling, then kill AppleSpell.service process.