Test to ensure people update db/schema.rb when they add a migration

database_schema_spec.rb

# spec/lint/database_schema_spec.rb

describe 'db/schema.rb' do
  it 'includes the changes from all migrations' do
    if checksum_line = File.read('db/schema.rb').split("\n").detect {|line| line.match /^# Checksum: \w+$/}
      checksum = checksum_line.match(/^# Checksum: (\w+)$/)[1]
      checksum.should == Digest::MD5.hexdigest(Dir.glob('db/migrate/*').sort.map {|path| File.read path}.join "\n")
    else
      fail 'db/schema.rb does not contain a migration directory checksum! Please run rake db:migrate'
    end
  end
end

migrate.rake

# lib/tasks/migrate.rake

namespace :db do
  task :migrate do
    checksum = Digest::MD5.hexdigest Dir.glob('db/migrate/*').sort.map {|path| File.read path}.join "\n"
    `echo '# Checksum: #{checksum}' >> db/schema.rb`
  end
end