Added that an DuplicateMigrationVersionError gets raised when multiple migrations have the same version number.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@2832 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

6 files changed, 63 insertions, 4 deletions

diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 90984b080b..bf4f9aa530 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -2,6 +2,12 @@ module ActiveRecord
   class IrreversibleMigration < ActiveRecordError#:nodoc:
   end
   
+  class DuplicateMigrationVersionError < ActiveRecordError#:nodoc:
+    def initialize(version)
+      super("Multiple migrations have the version number #{version}")
+    end
+  end
+  
   # Migrations can manage the evolution of a schema used by several physical databases. It's a solution
   # to the common problem of adding a field to make a new feature work in your local database, but being unsure of how to
   # push that change to other developers and to the production server. With migrations, you can describe the transformations
@@ -209,15 +215,22 @@ module ActiveRecord
 
     private
       def migration_classes
-        migrations = migration_files.collect do |migration_file|
+        migrations = migration_files.inject([]) do |migrations, migration_file|
           load(migration_file)
           version, name = migration_version_and_name(migration_file)
-          [ version.to_i, migration_class(name) ]
+          assert_unique_migration_version(migrations, version.to_i)
+          migrations << [ version.to_i, migration_class(name) ] 
         end
-        
+
         down? ? migrations.sort.reverse : migrations.sort
       end
-    
+      
+      def assert_unique_migration_version(migrations, version)
+        if !migrations.empty? && migrations.transpose.first.include?(version)
+          raise DuplicateMigrationVersionError.new(version)
+        end
+      end
+      
       def migration_files
         files = Dir["#{@migrations_path}/[0-9]*_*.rb"].sort_by do |f|
           migration_version_and_name(f).first.to_i
diff --git a/activerecord/test/fixtures/migrations_with_duplicate/1_people_have_last_names.rb b/activerecord/test/fixtures/migrations_with_duplicate/1_people_have_last_names.rb
new file mode 100644
index 0000000000..009729b330
--- /dev/null
+++ b/activerecord/test/fixtures/migrations_with_duplicate/1_people_have_last_names.rb
@@ -0,0 +1,9 @@
+class PeopleHaveLastNames < ActiveRecord::Migration
+  def self.up
+    add_column "people", "last_name", :string
+  end
+  
+  def self.down
+    remove_column "people", "last_name"
+  end
+end
\ No newline at end of file
diff --git a/activerecord/test/fixtures/migrations_with_duplicate/2_we_need_reminders.rb b/activerecord/test/fixtures/migrations_with_duplicate/2_we_need_reminders.rb
new file mode 100644
index 0000000000..ac5918f02a
--- /dev/null
+++ b/activerecord/test/fixtures/migrations_with_duplicate/2_we_need_reminders.rb
@@ -0,0 +1,12 @@
+class WeNeedReminders < ActiveRecord::Migration
+  def self.up
+    create_table("reminders") do |t|
+      t.column :content, :text
+      t.column :remind_at, :datetime
+    end
+  end
+  
+  def self.down
+    drop_table "reminders"
+  end
+end
\ No newline at end of file
diff --git a/activerecord/test/fixtures/migrations_with_duplicate/3_foo.rb b/activerecord/test/fixtures/migrations_with_duplicate/3_foo.rb
new file mode 100644
index 0000000000..916fe580fa
--- /dev/null
+++ b/activerecord/test/fixtures/migrations_with_duplicate/3_foo.rb
@@ -0,0 +1,7 @@
+class Foo < ActiveRecord::Migration
+  def self.up
+  end
+
+  def self.down
+  end
+end
\ No newline at end of file
diff --git a/activerecord/test/fixtures/migrations_with_duplicate/3_innocent_jointable.rb b/activerecord/test/fixtures/migrations_with_duplicate/3_innocent_jointable.rb
new file mode 100644
index 0000000000..21c9ca5328
--- /dev/null
+++ b/activerecord/test/fixtures/migrations_with_duplicate/3_innocent_jointable.rb
@@ -0,0 +1,12 @@
+class InnocentJointable < ActiveRecord::Migration
+  def self.up
+    create_table("people_reminders", :id => false) do |t|
+      t.column :reminder_id, :integer
+      t.column :person_id, :integer
+    end
+  end
+
+  def self.down
+    drop_table "people_reminders"
+  end
+end
\ No newline at end of file
diff --git a/activerecord/test/migration_test.rb b/activerecord/test/migration_test.rb
index 56d5e12090..9c5c2285b7 100644
--- a/activerecord/test/migration_test.rb
+++ b/activerecord/test/migration_test.rb
@@ -408,5 +408,11 @@ if ActiveRecord::Base.connection.supports_migrations?
       ActiveRecord::Base.table_name_suffix = ''
       Reminder.reset_table_name
     end
+    
+    def test_migrator_with_duplicates
+      assert_raises(ActiveRecord::DuplicateMigrationVersionError) do
+        ActiveRecord::Migrator.migrate(File.dirname(__FILE__) + '/fixtures/migrations_with_duplicate/', nil)
+      end
+    end
   end
 end