Be default the disklimit sandbox parameter limits output file sizes to 20 MB and the streamsize parameter limits stdout/stderr output to 2 MB. I don't remember any explicit limits on input, though there's always some sort of limit somewhere. But I recall pasting some huge input strings (several MB) into the web interface in the past.
Testing with 1000 integers is under any of those limits.
Likewise, I don't know of any limits on test cases except:
- If entering them through the web interface you'll get exhausted long before the limit is reached.
- The job still has to run in a few seconds (the default maximum run time on a Jobe server is 50 secs).
- The result table will become tediously long to read.
If you're planning on running large numbers of tests you probably want to use a combinator template grader - see the documentation. Then you can run computer-generated tests. Combinator template graders are non-trivial, but straightforward enough once you've got used to how they work. Most of our in-house question types nowadays use combinator template graders because they give you total control over how the code is tested and how results are displayed. I think that would be a much better approach than trying to manage questions via XML files.