Ditto other responses, but for emphasis: test-interview is largely a documents-check interview, but the documents being checked are the originals of those submitted in support of the application, and is for verification purposes, verification the documents submitted are genuine and the information in them is consistent, including stamps in the passport being consistent with reported travel.
Probably not a bad idea to have, in one's possession, some additional documents, like the Notices of Assessment, but odds are the interviewer will not be interested in extra documents. (I actually included my NoAs with my application; no idea if that had any effect at all, but I did take the oath barely eight months after applying, which is to say I am confident it did not have a negative impact, but cannot say it helped.)
I would also note that if CIC has questions about the applicant's employment, the interviewer may ask questions about this (and will ordinarily at the least ask questions like "what do you do?" or "where do you work?" and "are you working now?" although some applicants are asked more detailed questions than that). If a verbal response is not sufficient to answer the question to CIC's satisfaction, having documentation to show employment is not likely to avoid a follow-up written request to submit additional information and documentation. In particular, there are probably no additional documents an applicant can bring to the interview which will avoid RQ . . . either RQ is not in cards, or it will be issued. Not much the applicant can do to change things (well, except to change things negatively, such as by failing to present a passport or id card, or presenting one that reveals a discrepancy, or by saying something which raises questions).
Best to focus on following the instructions in the notice received, and be prepared for the test. That's enough for most applicants. More is not likely to fix things, at that stage, if CIC has identified an issue. (If there is a problem, CIC will make a documents request and that will be the applicant's opportunity to fix/address that problem).
.............Thanks Buddy