There’s another option now: update your deps and it should just work - https://twitter.com/plataformatec/status/1091300824251285504

Just wanted to comment on this. The team working on Elixir does their best to keep Elixir versions backwards-compatible. The worst thing you should get after upgrading to a newer version is a bunch of new deprecation warnings.

I would actually encourage you to upgrade early because if something does get deprecated, you can stop doing that in your code and reduce the amount of work that you would otherwise have to do if you decided to upgrade months later. Dependencies also keep working as before as a rule, but since you may start getting new warnings, that can be something that prompts you to look into gradually upgrading your dependencies as well sooner rather than later. This is again going to be easier than skipping a few version of Elixir and getting a lot more issues with dependencies when you finally decide to upgrade.

It looks like the project is already doing that. The test file starts with

defmodule Project.Module do
    use Project.ModelCase

And in model_case.ex we’ve got

  setup tags do
    :ok = Ecto.Adapters.SQL.Sandbox.checkout(Project.Repo)

    unless tags[:async] do
      Ecto.Adapters.SQL.Sandbox.mode(Project.Repo, {:shared, self()})
    end

    :ok
  end

So since :async isn’t included in the use line I believe that means we’re using shared mode, so any process should be able to connect to the DB connection.

I really don’t recommend this. If you’re testing or developing with a database type other than what you use in production you’re setting yourself up for great production surprises.

There’s a special need in this project where the program needs to run on a local computer of somebody who doesn’t have any programming knowledge. I used Docker in the beginning but then decided that SQLite + an executable produced by distillery would be the ultimate one-click solution. Of course it wouldn’t make sense to test or develop with a different DB type.

I guess a more reasonable thing for me to do might be to just open a different branch for that, while keeping the main version to be run on the server on the main branch. Now I’m creating an extra :local environment for this purpose, that’s why the abovementioned happened.