ruby on rails - wrong number of arguments (1 for 0) in rspec -

i problems tests after adding custom validation income model.

@member.incomes << [income.new(starting_date: '2015-01-01', amount: 1200, member: @member),                      income.new(starting_date: '2015-04-01', amount: 1400, member: @member)] 

i following error: wrong number of arguments (1 0)

my observation debugger:
first record correctly inserted, 2nd 1 getting error.

what i'm doing wrong - idea?

update:
concat method couldn't here.

more code:

income.rb validate :newly_added_income_is_also_the_newest? .... .. def newly_added_income_is_also_the_newest?   latest_income = income.where(member: member_id).select{|i|i}.max(&:starting_date)   return true if latest_income.nil?   if !latest_income.nil? && latest_income.starting_date >= starting_date     errors.add(:income, "newest income should latest income of member '#{member.full_name}''")   end end 

test: [budget] should incomes in between of start_date , end_date

@member.incomes.concat[income.new(starting_date: '2015-01-01', amount: 1200, member: @member),                             income.new(starting_date: '2015-04-01', amount: 1400, member: @member)]      budget = factorygirl.create(:budget, donation: @donation, member: @member)      expect(budget.get_all_incomes_for_budget_duration.size).to eq(3)  

log1

    1) budget tests budget based donation types [budget] should incomes in between of start_date , end_date          failure/error: @member.incomes.concat[income.new(starting_date: '2015-01-01', amount: 1200, member: @member),          typeerror:            no implicit conversion of income integer          # ./spec/models/budget_spec.rb:44:in `[]'          # ./spec/models/budget_spec.rb:44:in `block (3 levels) in <top (required)>'   

test2: [budget] should adapted promise income change between budget range (failed - 2)

it '[budget] should adapted promise income change between budget range', skip_before: true    member.delete_all    donation.delete_all    member = factorygirl.create(:member)    donation = factorygirl.create(:majlis_khuddam_donation)    #income = factorygirl.create(:income, member: member)     member.incomes << income.new(starting_date: '2015-01-01', amount: 1200, member_id: 12345) <<        income.new(starting_date: '2015-03-01', amount: 1000, member_id: 12345)     budget = factorygirl.create(:budget, donation: donation, member: member)     expect(budget.promise).to eq(123)  end 

log2

  2) budget tests budget based donation types [budget] should adapted promise income change between budget range        failure/error: income.new(starting_date: '2015-03-01', amount: 1000, member_id: 12345)        argumenterror:          wrong number of arguments (1 0)        # /users/user/.rvm/gems/ruby-2.2.0@maalify/gems/activerecord-4.2.0/lib/active_record/attribute_methods.rb:48:in `__temp__374716274796e676f546164756'        # ./app/models/income.rb:22:in `each'        # ./app/models/income.rb:22:in `max'        # ./app/models/income.rb:22:in `newly_added_income_is_also_the_newest?' 

i believe error occurs here:

latest_income = income.where(member: member_id).select{|i|i}.max(&:starting_date) 

max method defined in enumerable. not take argument, message "wrong number of arguments (1 0)".

you want method maximum, defined in activerecord. takes column name:

latest_income = income.where(member: member_id).maximum(:starting_date)