Your DD sounds so cute and funny! My DS would give silly answers to easy questions all the time at that age. We sometimes had opposite days in the house (still do).
We did warn his preschool teacher that he sometimes does things like that if he thinks it's easy; we suggested giving harder questions to see what he did, and never heard of any problems in preschool, so he probably just answered correctly. And during the kindergarten screening, which DS did at 3, he liked showing off to strangers, so he didn't mind answering any of the questions.
He went through a (short) phase where he wanted workbooks. So we did some. I found that if he did something once, he would do it correctly. If, later on, there was something basically the same, he would answer incorrectly on purpose. I ignored that and went on to newer material.
You mentioned possible testing. One time I did talk to him about giving correct answers was before his IQ test at age 4. I told him that he will probably be asked some questions that sound either too easy or too silly, but answer them anyway because you have to answer correctly to get to the more fun/interesting/challenging questions.
