Add support for Mysql column positioning via #add_column and #change_column

add_column and change_column in the Mysql adapter now accept some
additional options:
:first => true        # Put the column in front of all the columns
:after => column_name # Put the colmn after 'column_name'

add_column :new_col, :string, :first => true
add_column :another_col, :integer, :default => 0, :after => :new_col

[#3286 state:committed]

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>

1 files changed, 47 insertions, 0 deletions

diff --git a/activerecord/test/cases/migration_test.rb b/activerecord/test/cases/migration_test.rb
index 6d3f938799..0ef34e440a 100644
--- a/activerecord/test/cases/migration_test.rb
+++ b/activerecord/test/cases/migration_test.rb
@@ -527,6 +527,53 @@ if ActiveRecord::Base.connection.supports_migrations?
       assert !Person.column_methods_hash.include?(:last_name)
     end
 
+    if current_adapter?(:MysqlAdapter)
+      def testing_table_for_positioning
+        Person.connection.create_table :testings, :id => false do |t|
+          t.column :first, :integer
+          t.column :second, :integer
+          t.column :third, :integer
+        end
+
+        yield Person.connection
+      ensure
+        Person.connection.drop_table :testings rescue nil
+      end
+      protected :testing_table_for_positioning
+
+      def test_column_positioning
+        testing_table_for_positioning do |conn|
+          assert_equal %w(first second third), conn.columns(:testings).map {|c| c.name }
+        end
+      end
+
+      def test_add_column_with_positioning
+        testing_table_for_positioning do |conn|
+          conn.add_column :testings, :new_col, :integer
+          assert_equal %w(first second third new_col), conn.columns(:testings).map {|c| c.name }
+        end
+        testing_table_for_positioning do |conn|
+          conn.add_column :testings, :new_col, :integer, :first => true
+          assert_equal %w(new_col first second third), conn.columns(:testings).map {|c| c.name }
+        end
+        testing_table_for_positioning do |conn|
+          conn.add_column :testings, :new_col, :integer, :after => :first
+          assert_equal %w(first new_col second third), conn.columns(:testings).map {|c| c.name }
+        end
+      end
+
+      def test_change_column_with_positioning
+        testing_table_for_positioning do |conn|
+          conn.change_column :testings, :second, :integer, :first => true
+          assert_equal %w(second first third), conn.columns(:testings).map {|c| c.name }
+        end
+        testing_table_for_positioning do |conn|
+          conn.change_column :testings, :second, :integer, :after => :third
+          assert_equal %w(first third second), conn.columns(:testings).map {|c| c.name }
+        end
+      end
+    end
+
     def test_add_rename
       Person.delete_all