There are several aspects that don't click in your story.
You claim you have been assigned a Test Manager who has less seniority with the company than you do. This in itself should not be a problem, as it is your manager's job and responsibility to assign team management roles. Even if your colleague is a shaved ape (I.E: incompetent with no communication skills whatsoever), it's still not your job to contest his authority. He may be younger, dumber and less skilled than your are, but he is your manager's choice. If you have a problem with your manager's choice, feel free to take it up with him in a 1 on 1 meeting. Do not take your dissatisfaction for not being first choice for the role to your colleague. Take it up to the manager or the manager of the manager.
Furthermore, you seem to be upset by the way he chose to do his job (managing test plan creation and execution). Please note that this is HIS job, not yours, so he will be rewarded or punished for how it ends up being done. If his manner of communicating tasks to you and the test team is unfair, upsetting or inept, make notes of it and address them in a meeting with him and his boss. Make sure your arguments are full-proof and that there's nothing you could have done to make it better (or that he ignored all your requests for improvements).
Why would you assume he wants to make you look stupid? Maybe he has poor communication skills, or he simply doesn't know what to do. Try telling him his choice of relaying tasks is less than optimal and you are ready to help him improve if he wants it. Some technical aspects may be helped with your expertise, but communication gaps are usually outside of the scope of normal work relations.