I don't believe she's testing him. She could be, and it could be proven she was in the next chapter, but I say, no way. She literally just calmed down after blowing up on him because she was super stressed with her thesis. She has no time to think and come up with the idea of testing him right on the spot when she's emotionally and mentally exhausted.
I thought she'd use Hakdo's long-lasting crush on his bestie as a reason to break up tho.
I'm very curious what made Serizawa more emotional than usual this time. Because he was "feeling it more than usual" and let himself be more vulnerable than usual, Sanada finally realized what Serizawa was waiting for all this time and that they've been having this on and off affair for about 5-6 years when he realized what the next step was. Like.... Serizawa must have been on his wits end /on edge during this 14th year of their friendship.






If Mo actually knew how these two see him, he'd be like: "Where the hell did you 2 get the idea I'm your cure or smth? I didn't even do ANYTHING for you, Shen Li! I only cooked as your caretaker, He Tian!"