Fix adjustment metadata spec

spec/models/adjustment_metadata_spec.rb

@@ -2,7 +2,7 @@ require 'spec_helper'
 
 describe AdjustmentMetadata do
   it "is valid when built from factory" do
-    adjustment = build(:adjustment)
-    expect(adjustment).to be_valid
+    adjustment_metadata = build(:adjustment_metadata)
+    expect(adjustment_metadata).to be_valid
   end
 end