Upgraded to Rails 4, and now getting "wrong number of arguments (1 for 2+)" error - ruby-on-rails-4

Question

I recently upgraded my app from Rails 3 to Rails 4, and I'm trying to run the specification tests. Code that I presume used to work just fine (before my time here) suddenly throws an error.
The error:
1) Admin::ReviewsController while logged in #index should get index
Failure/Error: stub_search("product")
ArgumentError:
wrong number of arguments (1 for 2+)
# ./spec/support/searchkick_stub.rb:5:in `stub_search'
# ./spec/controllers/admin/reviews_controller_spec.rb:8:in `block (3 levels) in <top (required)>'
Here is the searchkick_stub.rb:
module SearchkickStub
def stub_search(model)
klass = model.to_s.camelize.constantize
klass.any_instance.stub(:reindex) { true }
klass.stub(:search) do |term, options|
options ||= {}
#search_term ||= term
#search_params ||= options.dup
response = {
'hits' => {
'total' => 0,
'hits' => [],
}
}
result_opts = {
# per Searchkick::Query.new
page: [options[:page].to_i, 1].max,
per_page: (options[:limit] || options[:per_page] || 100000).to_i,
padding: [options[:padding].to_i, 0].max,
load: options[:load].nil? ? true : options[:load],
# per Searchkick::Query.execute
includes: options[:include] || options[:includes],
json: !options[:json].nil?,
}
Searchkick::Results.new(klass, response, result_opts)
end
# Code that reindexes Products will reindex their Inventories too.
stub_search(:inventory) if model == :product
end
end
The signature of stub_search is clearly for a single argument, not two or more like the error claims.
And here is where we use stub_search in reviews_controller_spec.rb
describe ReviewsController do
include SearchkickStub
before do
stub_search(:product)
...
end
end

Answer 1

Figured it out. Per https://github.com/rspec/rspec-rails/issues/941, the issue was the line: require 'minitest/autorun' in spec_helper.rb. This line was added to remove the followig warnings:
Warning: you should require 'minitest/autorun' instead.
Warning: or add 'gem "minitest"' before 'require "minitest/autorun"'
But it turns out that all you need is gem "minitest" in the Gemfile (even though it was already installed, as a dependency for something else, and appeared in Gemfile.lock).

Answer 2

I think the issue comes more from the ruby upgrade. There may have been changes to the interpreter around how block arguments were handled. The search method is stubbed to take 2 arguments in your code: term and options. But it's only invoked with one argument: "product".
options is set to a default value on the first line in that block with options ||= {} so not passing options may not have been a problem with 1.9.3, but with stricter argument checks it breaks in 2.1.5.
A simple fix is to set a default argument in the block arguments, eg.
klass.stub(:search) do |term, options|
to
klass.stub(:search) do |term, options={}|
You can also safely remove the options ||= {} line after doing this.