Rails 7 deprecates Enumerable#sum and Array#sum

Rails 7 deprecates Enumerable#sum to the calls with non-numeric arguments. To ignore the warning we should use a suitable initial argument.

Before Rails 7

=> %w[foo bar].sum
=> "foobar"

=> [[1, 2], [3, 4, 5]].sum
=> [1, 2, 3, 4, 5]

After Rails 7

=> %w[foo bar].sum
=> Rails 7.0 has deprecated Enumerable.sum in favor of Ruby's native implementation available since 2.4.
   Sum of non-numeric elements requires an initial argument.

=> [[1, 2], [3, 4, 5]].sum
=> Rails 7.0 has deprecated Enumerable.sum in favor of Ruby's native implementation available since 2.4.
   Sum of non-numeric elements requires an initial argument.

To avoid the deprecation warning, we should use suitable argument as below.

=> %w[foo bar].sum('')
=> "foobar"

=> [[1, 2], [3, 4, 5]].sum([])
=> [1, 2, 3, 4, 5]

Check out this pull request for more details.