generate migrations with new .change method for rails >= 3.1. closes h…

…eartcombo#1345

lib/generators/active_record/templates/migration.rb

@@ -1,5 +1,9 @@
 class DeviseCreate<%= table_name.camelize %> < ActiveRecord::Migration
+<% if ::Rails::VERSION::MAJOR == 3 && ::Rails::VERSION::MINOR >= 1 -%>
+  def self.change
+<% else -%>
   def self.up
+<% end -%>
     create_table(:<%= table_name %>) do |t|
       t.database_authenticatable :null => false
       t.recoverable
@@ -11,7 +15,7 @@ def self.up
       # t.lockable :lock_strategy => :<%= Devise.lock_strategy %>, :unlock_strategy => :<%= Devise.unlock_strategy %>
       # t.token_authenticatable
 
-<% for attribute in attributes -%>
+<% attributes.each do |attribute| -%>
       t.<%= attribute.type %> :<%= attribute.name %>
 <% end -%>
 
@@ -25,7 +29,9 @@ def self.up
     # add_index :<%= table_name %>, :authentication_token, :unique => true
   end
 
+<% unless ::Rails::VERSION::MAJOR == 3 && ::Rails::VERSION::MINOR >= 1 -%>
   def self.down
     drop_table :<%= table_name %>
   end
+<% end -%>
 end

lib/generators/active_record/templates/migration_existing.rb

@@ -5,13 +5,13 @@ def self.up
       t.recoverable
       t.rememberable
       t.trackable
-    
+
       # t.encryptable
       # t.confirmable
       # t.lockable :lock_strategy => :<%= Devise.lock_strategy %>, :unlock_strategy => :<%= Devise.unlock_strategy %>
       # t.token_authenticatable
 
-<% for attribute in attributes -%>
+<% attributes.each do |attribute| -%>
       t.<%= attribute.type %> :<%= attribute.name %>
 <% end -%>
 
@@ -29,6 +29,6 @@ def self.up
   def self.down
     # By default, we don't want to make any assumption about how to roll back a migration when your
     # model already existed. Please edit below which fields you would like to remove in this migration.
-    raise ActiveRecord::IrreversibleMigration   
+    raise ActiveRecord::IrreversibleMigration
   end
 end

test/generators/active_record_generator_test.rb

@@ -7,20 +7,30 @@ class ActiveRecordGeneratorTest < Rails::Generators::TestCase
     tests ActiveRecord::Generators::DeviseGenerator
     destination File.expand_path("../../tmp", __FILE__)
     setup :prepare_destination
-  
+
     test "all files are properly created" do
-      run_generator %w(monster)
-      assert_file "app/models/monster.rb", /devise/, /attr_accessible (:[a-z_]+(, )?)+/
-      assert_migration "db/migrate/devise_create_monsters.rb"
+      with_rails_version :MAJOR => 3, :MINOR => 0 do
+        run_generator %w(monster)
+        assert_file "app/models/monster.rb", /devise/, /attr_accessible (:[a-z_]+(, )?)+/
+        assert_migration "db/migrate/devise_create_monsters.rb", /def self\.up/
+      end
     end
-
+
+    test "all files are properly created with rails31 migration syntax" do
+      with_rails_version :MAJOR => 3, :MINOR => 1 do
+        run_generator %w(monster)
+        assert_file "app/models/monster.rb", /devise/, /attr_accessible (:[a-z_]+(, )?)+/
+        assert_migration "db/migrate/devise_create_monsters.rb", /def self\.change/
+      end
+    end
+
     test "update model migration when model exists" do
       run_generator %w(monster)
       assert_file "app/models/monster.rb"
       run_generator %w(monster)
       assert_migration "db/migrate/add_devise_to_monsters.rb"
     end
-  
+
     test "all files are properly deleted" do
       run_generator %w(monster)
       run_generator %w(monster)

test/support/helpers.rb

@@ -57,4 +57,20 @@ def swap(object, new_values)
       object.send :"#{key}=", value
     end
   end
+
+  def with_rails_version(constants, &block)
+    saved_constants = {}
+    constants.each do |constant, val|
+      saved_constants[constant] = ::Rails::VERSION.const_get constant
+      Kernel::silence_warnings { ::Rails::VERSION.const_set(constant, val) }
+    end
+
+    begin
+      block.call
+    ensure
+      constants.each do |constant, val|
+        Kernel::silence_warnings { ::Rails::VERSION.const_set(constant, saved_constants[constant]) }
+      end
+    end
+  end
 end