Poastmonger

And GLaDOS interjects like, "You didn't do this. She did all the work!"

I find that interjection fascinating because. Like.

GLaDOS doesn't actually know anything about what happened behind the scenes. She lost track of Chell and Wheatley after Wheatley opened up a wall panel and they bolted off together into the facility's inner workings. She doesn't see them again until Chell falls for her fake door trap, at which point GLaDOS is unpleasantly surprised to discover that Chell's disabled the turrets and neurotoxin in the meantime.

She has no evidentiary foundation to base that accusation on.

This is also before GLaDOS recognizes Wheatley as the Dumbass Core, so it's not based on an assessment of him.

The only explanation it leaves is that it's based on her assessment of Chell. Despite GLaDOS's enmity towards Chell, the one thing she rarely goes after Chell for is her intelligence.

When she does, it's an admission of her high standards for Chell; Like when the fake door trap works and GLaDOS concedes, "I didn't actually think that would work. I already built a much better, smarter trap up ahead for when this one fails." That's a backhanded insult. It's calling her dumb, but in a disappointed way rather than an affirming way.

Chell tests very well. Between the two games, GLaDOS has developed a strong understanding of Chell's aptitude for critical thinking and problem-solving in stressful situations.