Inspecting dependency package version at runtime

[danschultzer]

@mike_bianco

{:poison, "~> 2.0 or ~> 3.0 or ~> 4.0"}

In deps but use version ~> 4.0 for the tests in the package.

You can just set it up like that, and run mix deps.update poison. It’ll fetch the most recent 4.x version.

If you need to test different versions in CI, then I would add a second mix.lock file, and do it similar to how Phoenix does it: phoenix/mix.exs at f3fe0188aaa53bfa10d7750cffe5008d211756bf · phoenixframework/phoenix · GitHub

@mike_bianco

For some reason, it looks like this data isn’t available when running tests in the geoip gem:

pry(4)> :application.get_key :poison, :vsn
:undefined

That error would mean that Poison isn’t loaded before you run :application.get_key/2 in the current process. Have you checked that it’s loaded just before calling :application.get_key/2?