Fix spec flake in GpoConfirmationUploader

app/services/gpo_confirmation_uploader.rb

@@ -1,6 +1,6 @@
 class GpoConfirmationUploader
-  def initialize
-    @now = Time.zone.now
+  def initialize(now = Time.zone.now)
+    @now = now
   end
 
   def run

spec/services/gpo_confirmation_uploader_spec.rb

@@ -1,7 +1,8 @@
 require 'rails_helper'
 
 RSpec.describe GpoConfirmationUploader do
-  let(:uploader) { described_class.new }
+  let(:uploader) { described_class.new(now) }
+  let(:now) { Time.zone.now }
 
   let(:export) { 'foo|bar' }
   let(:confirmations) do
@@ -52,12 +53,13 @@
     subject { uploader.send(:upload_export, export) }
 
     let(:sftp_connection) { instance_double('Net::SFTP::Session') }
-    let(:string_io) { StringIO.new(export) }
 
     it 'uploads the export via sftp' do
       expect(Net::SFTP).to receive(:start).with(*sftp_options).and_yield(sftp_connection)
-      expect(StringIO).to receive(:new).with(export).and_return(string_io)
-      expect(sftp_connection).to receive(:upload!).with(string_io, upload_folder)
+      expect(sftp_connection).to receive(:upload!) do |string_io, folder|
+        expect(string_io.string).to eq(export)
+        expect(folder).to eq(upload_folder)
+      end
 
       subject
     end
@@ -115,7 +117,7 @@ def sftp_options
   end
 
   def upload_folder
-    timestamp = Time.zone.now.strftime('%Y%m%d-%H%M%S')
+    timestamp = now.strftime('%Y%m%d-%H%M%S')
     File.join(IdentityConfig.store.usps_upload_sftp_directory, "batch#{timestamp}.psv")
   end