There's a difference between reading and writing, and reading and writing well. I would expect the tests to expect higher proficiency than what is expected in your usual text messages.
While you can certainly argue that some texts have more substance to them than these literary works, you cannot deny that most texts have worse prose than the books.
> The quality of most text msgs is higher than what passes for “quality literature” in many lit classrooms.
First: Your HS kids hang out with a different crowd than my HS kids :-)
Second: This is about reading ability (comprehension, etc), not literature. Whether the quality of a text message is superior/inferior to whatever they use in literature classes is irrelevant.