I would like to know how to test my package against multiple versions of the dependency packages in a CI environment. For example, it would be great to be able to test against the CRAN versions of the dependencies as well as the in-development Github versions to get early warning about breaking changes. Alternatively, I'd like to be able to test against old package versions to make sure I'm not unintentionally making my code depend against latest CRAN package versions.
The travis-ci R community documentation shows how to test a package on travis against a matrix of r versions:
language: r r: - oldrel - release - devel
However, package versions derive from either a package DESCRIPTION file or a packrat lockfile, either of which only results in a single set of package versions. I gather Rstudio package manager may cover this use case, but I don't have access to it. Perhaps there is a way to have multiple packrat/renv lockfiles and test against each one?