Bob and Shirley attempted to form a corporation for the restaurant Bob & Shirley's. Bob and Shirley inadvertently failed to file the articles of incorporation. Can they still be treated as a corporation? If yes, how and in which situations?

If I am not mistaken, this would still be considered a corporation under intent, correct? If not, please elaborate in as much detail as possible. Roughly 10 or more sentences.

Technically, there is no country, state, or locality listed in the question. However, my guess is that it pertains to the United States.