a) Critically evaluate the test for dishonesty under the Theft Act 1968.

b) While shopping at a supermarket, Mary picks up a tin of fruits and puts it in her handbag. She notices that the stockroom door is open. She enters the stockroom and takes two apples and puts them in her handbag. While queuing at the checkout, she notices the manager watching her. Fearing he has seen what she had done earlier, she transfers the tin from her handbag into the supermarket trolley and pays for it.

Discuss Mary's criminal liability, if any.

Please describe up to one thousand five hundred words. Please insert relevant cases with authorities. Thank you.