This test verifies that, after reversion panel is shown, continue deleting the word will dismiss the reversion panel.
After seeing the reversion panel, start deleting the corrected word character by character. You should see the panel being dismissed once you start deleting.
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.