nested form: test fails when using a custom validation method

[Javix]

I'm trying to validate a nested association as follows:

#timesheet.rb

class Timesheet < ActiveRecord::Base

  attr_accessible :status, :user_id, :start_date, :end_date, :activities_attributes

  

  SUBMITTED = 'Submitted'

  APPROUVED = 'Approuved'

  REJECTED = 'Rejected'

  

  STATUS_VALUES = [SUBMITTED, APPROUVED, REJECTED]

  belongs_to :user

  has_many :activities, dependent: :destroy, inverse_of: :timesheet

  has_many :time_entries, through: :activities

  accepts_nested_attributes_for :activities, allow_destroy: true

  

  validates :status, presence: true, inclusion: {in: STATUS_VALUES}  

  validates :user_id, :start_date, :end_date, presence: true

  validate :maximum_worktime_per_day

  

  after_update :check_an_activity_present

  private

    def maximum_worktime_per_day

      time_entries_by_date = time_entries.group_by(&:workdate)

      time_entries_by_date.each do |key, value|

        errors[:base] << "Maximum daily time should not exceed 1 day" if worktime_by_date(value) > 1

        break

      end

    end

end

Here is a spec to test it:

describe "when worked time per day is greater than 1 day" do

    it "should not be valid" do

      new_timesheet = build(:submitted_timesheet)

      activity = new_timesheet.activities.first

      time_entry_1 = build(:time_entry, activity: activity, workdate: Date.today.beginning_of_week, worktime: 1.0)

      activity_2 = build(:activity, timesheet: new_timesheet)

      time_entry_2 = build(:time_entry, activity: activity_2, workdate: Date.today.beginning_of_week, worktime: 1.0)

      expect(new_timesheet).to_not be_valid      

    end    

  end

I'd like just to validate that the maximum worked time per day should not greater than 1.0 (accepted values are 0.5 or 1.0 defined in TimeEntry model).

I create a new timesheet instance in a nested form. The error is never raised when creating a new tie sheet. But when editing it, the validation catches well the error even if I modify the wrong value or remove completely a nested instance. I have an impression that the collection is not refreshed before running the validation method.

I even opened an issue at rails git : https://github.com/rails/rails/issues/9934, but still no solution found. Any idea on what is going wrong here? Thank you.