Add deterministic XXH64 hashing specs (#4460)

Author: philippthun

spec/unit/lib/cloud_controller/diego/staging_action_builder_spec.rb

@@ -0,0 +1,34 @@
+require 'spec_helper'
+require 'cloud_controller/diego/staging_action_builder'
+
+module VCAP::CloudController
+  module Diego
+    RSpec.describe StagingActionBuilder do
+      subject(:builder) { described_class.new(config, nil, nil, nil, nil, nil, nil) }
+
+      let(:config) { Config.new({ staging: { legacy_md5_buildpack_paths_enabled: } }) }
+
+      describe '#buildpack_path' do
+        context 'when legacy_md5_buildpack_paths_enabled is false' do
+          let(:legacy_md5_buildpack_paths_enabled) { false }
+
+          it 'hashes buildpack key using XXH64' do
+            expect(builder.send(:buildpack_path, 'key')).to eq('/tmp/buildpacks/447762562de14334')
+          end
+
+          it 'preserves leading zeros in the hash' do
+            expect(builder.send(:buildpack_path, 'cl')).to eq('/tmp/buildpacks/00d7b37f249a2722')
+          end
+        end
+
+        context 'when legacy_md5_buildpack_paths_enabled is true' do
+          let(:legacy_md5_buildpack_paths_enabled) { true }
+
+          it 'uses MD5 to hash the buildpack key' do
+            expect(builder.send(:buildpack_path, 'key')).to eq('/tmp/buildpacks/3c6e0b8a9c15224a8228b9a98ca1531d')
+          end
+        end
+      end
+    end
+  end
+end

spec/unit/middleware/mixins/user_reset_interval_spec.rb

@@ -10,6 +10,10 @@ module Middleware
       let(:reset_interval_in_minutes) { 60 }
       let(:user_guid_offset) { 592.seconds }
 
+      it 'produces the expected XXH64 hash' do
+        expect(Digest::XXH64.idigest(user_guid)).to eq(16_213_529_883_637_274_992)
+      end
+
       context "time is set to beginning of hour + the user's offset" do
         before { Timecop.freeze Time.now.beginning_of_hour + user_guid_offset }
         after { Timecop.return }