Helpers around testing with Snap.

Unlike SQL databases, ElasticSearch/OpenSearch does not provide transaction isolation, which is how Ecto.Adapters.SQL.Sandbox isolates test processes, allowing multiple tests to run asynchronously.

Snap uses a different approach. It can set an index namespace for a running process, which scopes all the convenience API operations to that index namespace, so they don't collide with each other.

This allows tests to run asynchronously, improving the performance.

To set this up, you'll want to use tags in ExUnit

In your test you'll do something similar to:

setup context do
  if context[:snap] do
    namespace = Snap.Test.generate_namespace_for_pid(self())
    Snap.Cluster.Namespace.set_process_namespace(Cluster, namespace)
    Snap.Test.drop_indexes(Cluster)

    on_exit(fn ->
      Snap.Cluster.Namespace.set_process_namespace(Cluster, namespace)
      Snap.Test.drop_indexes(Cluster)
    end)
  end
end

@tag :snap
test "test something with snap" do
  ...
end

This generate a unique namespace for the running process and assigns to the cluster. It clears the indexes to make sure the test is starting from scratch.

It setups up a on_exit/1 callback, which runs in a separate process after the test has completed. The namespace is passed through from the test's process, so it can teardown all the indexes created by the test.