This works

spec/unit/shoulda/matchers/active_record/have_db_index_matcher_spec.rb

@@ -3,8 +3,20 @@ require 'unit_spec_helper'
 describe Shoulda::Matchers::ActiveRecord::HaveDbIndexMatcher, type: :model do
   context 'have_db_index' do
     it 'accepts an existing index' do
-      expect(with_index_on(:age1, parent_class: DevelopmentRecord)).to have_db_index(:age1)
-      expect(with_index_on(:age2, parent_class: ProductionRecord)).to have_db_index(:age2)
+      model_connected_to_development = with_index_on(
+        :age1,
+        model_name: 'EmployeeInDevelopment',
+        table_name: 'employees_in_development',
+        parent_class: DevelopmentRecord,
+      )
+      model_connected_to_production = with_index_on(
+        :age2,
+        model_name: 'EmployeeInProduction',
+        table_name: 'employees_in_production',
+        parent_class: ProductionRecord,
+      )
+      expect(model_connected_to_development).to have_db_index(:age1)
+      expect(model_connected_to_production).to have_db_index(:age2)
     end
 
     it 'rejects a nonexistent index' do
@@ -78,11 +90,15 @@ describe Shoulda::Matchers::ActiveRecord::HaveDbIndexMatcher, type: :model do
   end
 
   def with_index_on(column_name, index_options = {})
+    model_name = index_options.delete(:model_name) || 'Employee'
+    table_name = index_options.delete(:table_name) || 'employees'
     parent_class = index_options.delete(:parent_class) || ActiveRecord::Base
 
-    create_table('employees', connection: parent_class.connection) do |table|
+    create_table(table_name, connection: parent_class.connection) do |table|
       table.integer column_name
-    end.add_index(:employees, column_name, index_options)
-    define_model_class('Employee', parent_class: parent_class).new
+    end.add_index(table_name.to_sym, column_name, index_options)
+    define_model_class(model_name, parent_class: parent_class) do |model|
+      model.table_name = table_name
+    end.new
   end
 end