All 5 Uses of

positive
in
Change of Heart, by Picoult

I need a drink," I told him, and he cocked an ear, because after all it was only 11:45 a.m. I went straight to the refrigerator—in spite of what my mother likely imagined, the only food inside of it was ketchup, a jar of pimientos, Ollies carrots, and yogurt with an expiration date from Bill Clinton's administration—and poured myself a glass of Yellow Tail chardonnay I wanted to be pleasantly buzzed before I turned on the television set, where no doubt my fifteen minutes of fame was now going to be marred by a suit with stripes that made my already plus-size butt look positively planetary.†

positively = with certainty

One night, when I was on duty, the inmates got intoxicated, and sure enough the pipes tested positive for alcohol residue one day, although the water source tested perfectly normal.
*

positive = indicating that a condition was found

So the water tested positive for something that looked like alcohol, but only in certain pipes.

"Here," he said, and I absolutely, positively stopped breathing.
*

positively = with certainty

Definitions:

(1) (positive as in: I'm absolutely positive!)
certain (having no doubt; or used for emphasis)
(2) (positive as in: had a positive effect)
good or beneficial
(3) (positive as in: positive feedback from my boss)
approval or agreement
(4) (positive as in: a positive attitude)
optimistic (expecting or focusing on good things); or agreeable
(5) (positive as in: The test came back positive.)
found a condition or substance to be present
indicating the presence of something being tested for -- especially a disease, condition, or substance
(6) (positive as in: a positive number)
greater than zero (of a number)
(7) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

See a comprehensive dictionary for less common meanings of positive including some in the fields of electricity, physics, chemistry, medicine, philosophy, and grammar. Note that most all senses of positive indicate that something is good or present.