Just Testing You

Alice asks a question. Bob looks at her incredulously and gives an answer. His tone conveys, quite clearly, that she should know this already. Alice is embarrassed, and in a feeble attempt to cover her ignorance, informs Bob that she was "Just Testing You." Stock Phrase, usually accompanied by excessive blushing and a sheepish grin.

Anime and Manga
""Is this thing [dog whistle] on? I can't hear it." "It's a frequency too high for humans to hear." "[Awkward pause] I knew that. I was testing you.""
 * Cowboy Bebop:

Comic Books

 * In one instalment of Dinosaur Comics, God himself asks T-Rex where wind comes from, and defends himself: "UM OF COURSE I KNOW I JUST WANT TO SEE IF YOU DO"
 * Seen in an E-Man parody of Marvel Comics--Pointy-Haired Boss Stanley Presents is hideously out of touch with the current continuity his company prints, and keeps making references to things that haven't been true for over a decade. When called on it, "I know that, I was just testing you."

Literature
""Even school teachers know that one!""
 * In the Discworld book Making Money, when Mr. Bent has a paper corrected by one of his younger employees and suffers a breakdown, Moist initially wonders why he simply didn't claim he was testing them.

Live-Action TV
"Sam: We've seen that wreath before, Dean. Dean: Where? Sam: The Walshes. Yesterday. Dean: [trying to cover] ...I know... I was just testing you..."
 * The Supernatural episode "A Very Supernatural Christmas":


 * Done in an episode of the original Star Trek. Kirk and Spock set up a challenge/response password before Kirk beamed down to a planet in order to prevent imposters from getting beamed up. Naturally a shapeshifter takes Kirk's form and tries to get Spock to beam him up. When he doesn't know the password, he tries to cover it up by saying that he was just testing Spock. Spock catches on immediately and concludes that Kirk must be in trouble, since the real Kirk would never "test" him like that.
 * In the WKRP episode "Put Up or Shut Up," Johnny Fever has a drug flashback. He asks Andy, the station manager, "Do you see anybody over in that corner?" After Andy says no, Johnny says, "Neither do I. Just testing you."

Video Games

 * Played on several levels in Knights of the Old Republic. Bastila asks you a few simple questions about your background. You can answer truthfully or sarcastically. She admits to testing you to see if you were honest and able to treat the Force Bond seriously. What she's really testing

Western Animation
"New York kid: Oh brother, you guys don't even know what "queef" means? Stan: Of course we know what "queef" means! New York kid: Yeah? What is it, then? Kyle: Why? Don't you know?"
 * A variant occurs with kids, usually regarding a rude word or a sexual/bodily function. From South Park:

"Jimmy: May I suggest that instead of the arm-missiles button, you push the one right below it? Carl: I know what button to push! I was just testing you."
 * Jimmy Neutron episode "Carl Wheezer Boy Genius"