You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: test_fulfillment_inventory_client.rb
    path of file: ./repos/peddler/test/unit/mws
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

require 'helper'
require 'mws/fulfillment_inventory/client'

class TestMWSFulfillmentInventoryClient < Min
    
  def test_listing_inventory_supply
    operation = {
      'Action' => 'ListInventorySupply',
      'SellerSkus.member.1' => '1'
    }

    @client.stub(:run, nil) do
      @client.list_inventory_supply(seller_skus: '1')
    end

    assert_equal operation, @client.operation
  end