Also create a joined table so the test won't fail

spec/shoulda/active_model/validate_presence_of_matcher_spec.rb

@@ -90,6 +90,10 @@ describe Shoulda::Matchers::ActiveModel::ValidatePresenceOfMatcher do
         has_and_belongs_to_many :children
         validates_presence_of :children
       end.new
+      create_table "children_parents", :id => false do |t|
+        t.integer :child_id
+        t.integer :parent_id
+      end
     end
 
     it "should require the attribute to be set" do
@@ -103,6 +107,10 @@ describe Shoulda::Matchers::ActiveModel::ValidatePresenceOfMatcher do
       @model = define_model :parent do
         has_and_belongs_to_many :children
       end.new
+      create_table "children_parents", :id => false do |t|
+        t.integer :child_id
+        t.integer :parent_id
+      end
     end
 
     it "should not require the attribute to be set" do

spec/support/model_builder.rb

@@ -12,12 +12,12 @@ module ModelBuilder
     end
   end
 
-  def create_table(table_name, &block)
+  def create_table(table_name, options = {}, &block)
     connection = ActiveRecord::Base.connection
 
     begin
       connection.execute("DROP TABLE IF EXISTS #{table_name}")
-      connection.create_table(table_name, &block)
+      connection.create_table(table_name, options, &block)
       @created_tables << table_name
       connection
     rescue Exception => e