# Shows the discrepancy between the `embeds_one` & `embeds_many` build API:
#
# - `embeds_many` accepts a class as a second argument on `build`
# - `embeds_one` does not
#
# After some experimentation, you can work around this with `_type` in the attrs,
# but I would expect the build API to be consistent between the two
# 
# Issue exists in upstream v6, v7, v8
class BatchOperation
  include Mongoid::Document

  embeds_one :fetcher
  embeds_many :fetchers
end

class Fetcher
  include Mongoid::Document
  embedded_in :batch_operation
end

class FileFetcher < Fetcher
end

class PageFetcher < Fetcher
end

BatchOperation.collection.drop

operation = BatchOperation.create
operation.build_fetcher({}, FileFetcher)
operation.fetchers.build({}, PageFetcher)
# Expected: [ FileFetcher, PageFetcher ]
# Upstream: [ Fetcher, PageFetcher ]
pp [operation.fetcher.class, operation.fetchers[0].class]

# This saves immediately so isn't suitable:
# operation.fetcher = FileFetcher.new

# This can work, but is inconsistent with the embeds_many API
# operation.build_fetcher(_type: "FileFetcher")