Why did He feel the need to constantly test her?

Richard had the feeling the two of them were constantly testing each other, but in ways he couldn't see.

The machines constantly test drugs and feed the results into computers.

They were constantly tested, studied, and examined, with records being taken of everything.

He was constantly testing the limits of decorum and good taste.

He constantly tests Tarak's leadership and control over the troop.

But you constantly test how far you may go.

We deal with our coaching staff constantly testing us physically, mentally and even sometimes spiritually.

Yet like Cragg he is constantly testing stereotypes and myths.

Case officers should constantly test their agents for changes in motivation or possible counterintelligence compromise.