A Storehouse.Adapter that keeps files in memory, for tests: every callback, the optional ones too, with no disk, no bucket and no container, and each test's files its own, as Ecto's sandbox keeps each test's rows.

# test/test_helper.exs
{:ok, _pid} = Storehouse.Memory.start_link()
ExUnit.start()

# config/test.exs
config :storehouse, adapter: Storehouse.Memory

# in a test, or a case template's setup
setup do
  Storehouse.Memory.checkout()
end

Whose files

A process that has called checkout/0 owns the files it stores, and sees only those: two tests run with async: true never see each other's files, even under the same key. The processes it starts with Task see them too (they carry it in $callers), and any other process once allow/2 lets it. A file a process stores before any checkout goes to a space every such process shares. An owner's files go when it exits.

Uploads straight to the store

presign_upload/3 gives an upload whose URL no server takes: in a test, make the browser's part of it with put_upload/2, which takes the bytes as the store would, of the signed type and size only.

Failures

fail_next/2 makes the next call of a callback give an error, for the tests of an app's error paths:

Storehouse.Memory.fail_next(:delete, :unavailable)
assert {:error, :unavailable} = Storehouse.delete(key)

See Storehouse.Test for assertions on what was stored.