team_spec.rb

RSpec.describe Team, :type => :model do
  let(:admin) { create(:user, role: Role::ADMIN, first_name: 'Administrator') }
  let(:man) { create(:user, role: Role::COACH, first_name: 'Coach') }


  it "doesn't allow for more than 4 teams for a sponsor" do
    create_list(:team, 4, sponsor: admin)
    admin.reload

    admin.sponsored_teams.build(sponsor: admin)
    admin.save

    expect(admin.sponsored_teams.count).to eq(4)
  end

  it "if more than 4 team sponsored new team goes to first downline" do
    create(:team, sponsor: admin, coach: man)
    3.times do
      create(:team, sponsor: admin)
    end

    admin.sponsored_teams.build(sponsor: admin)
    admin.save

    expect(man.sponsored_teams.count).to eq(1)
  end


end

trying.rb

  def foo(team)
    # check current sponsor sponsored teams
    # if equal or greather than 4
      # find the first coach of a sponsored team by current sponsor and add the
      # team as a sponsored team of coach
    # else
    # :
    if team.sponsor.sponsored_teams.count >= 4
      u = User.find(team.sponsor.id)
      foo = User.find(u.sponsored_teams.first.coach.id)
      team = foo.sponsored_teams << team
      return team
    else
    end
  end

u = team.sponsor # avoid the extra lookup from `User.find`. u is the sponsor.
foo = u.sponsored_teams.first.coach # again avoid an extra lookup.