I have a very toxic colleague. He talks a lot behind people's backs and the union context makes him impossible to fire. He's the team coordinator but he doesn't really have any power over me.
Having said that, recently he's been doing little tests on me (I don't know if I'm the only one) to see if I'm working when I'm “green” on teams, for exemple sometimes he send me a useless message very late at night as if he wanted to see what time I start the next day.
It's very insidious, and not concrete enough for me to tell my boss. On the other hand, I wonder whether I'm just pretending nothing's happened and answering his tests as if I hadn't understood his purpose? Or do I confront him?