Test failed on Gradescope when answers are correct

[JiajingZ]

Describe the bug
closely followed the otter sample, the tests failed for "q2a" and "q3b" on the Gradescope while the answers are correct in the tested submission Rmd. files and tests can be passed when running locally in R. See pictures below:

To Reproduce
Follow exactly the steps at https://github.com/ucbds-infra/ottr-sample using files in folder "hw01"

Expected behavior
all tests should pass for the tested submission .Rmd file.

Version
Python version: 3.7.3
Otter-Grader version: 1.1.5

[sukhjitsehra]

You have to include requirements.R file when creating autograder.zip file. that includes cran location for R.