I am a junior at a public university in US studying CS. Since start of spring semester of this year, I began working with a professor for undergraduate research (with hope of doing a senior thesis project with him). The problem is that he hasn't really given a project to me (and I don't know well enough about the field to propose a project). Instead, I've just been helping out other people in the lab test their project and doing minor work. At first, I decided to be patient and do the grunt work, thinking that I would learn something from it. But as the semester is ending, I'm starting to feel that I haven't gained much from the work. I honestly feel that I'm not even part of the lab.
I met with him recently and he still hasn't really settled on a project for me to start in my senior year. He has suggested some new topics he might be interested but I'm not even sure I'll be working on that. I decided to stop waiting and look for another professor to work. I found one who was willing to work with me. I feel optimistic about working with the new professor. I did not tell him about my work with the other professor.
I was thinking about telling the first professor (let's call him A) that I intend to work with another professor (Professor B), but (1) I'm not sure how professor A would react and (2) B and A have collaborated before and during the meeting, Professor B hinted that my project might involve collaboration with other faculty (which would include A).
I'm not sure how to proceed with this issue. If I was working on a project for Professor A, I know it would be wrong to switch suddenly to Professor B. But I'm not even doing anything in A's lab. So is it fine if I went ahead and just tell A even if I might have to collaborate with him later. Also, should I tell Professor B about my history with Professor A?