module ThoughtBot::Shoulda::ActiveRecord::Macros

def should_have_indices(*columns)


should_have_index :age
should_have_indices :email, :name, [:commentable_type, :commentable_id]

Also aliased to should_have_index for readability
Ensures that there are DB indices on the given columns or tuples of columns. 
def should_have_indices(*columns)
  table = model_class.table_name
  indices = ::ActiveRecord::Base.connection.indexes(table).map(&:columns)
  columns.each do |column|
    should "have index on #{table} for #{column.inspect}" do
      columns = [column].flatten.map(&:to_s)
      assert_contains(indices, columns)
    end
  end
end