diff --git a/lib/smart_answer/question/base.rb b/lib/smart_answer/question/base.rb
index 8d0b6a8abe1..039d76673c1 100644
--- a/lib/smart_answer/question/base.rb
+++ b/lib/smart_answer/question/base.rb
@@ -15,8 +15,12 @@ def initialize(flow, name, options = {}, &block)
         super
       end
 
-      def next_node(next_node = nil, &block)
+      def next_node(next_node = nil, permitted: [], &block)
         if block_given?
+          unless permitted.any?
+            raise "You must specify the permitted next nodes"
+          end
+          @permitted_next_nodes += permitted
           @default_next_node_function = block
         elsif next_node
           next_node_if(next_node)
@@ -44,6 +48,9 @@ def next_node_for(current_state, input)
         next_node = next_node_from_function_chain(current_state, input) || next_node_from_default_function(current_state, input)
         responses_and_input = current_state.responses + [input]
         raise NextNodeUndefined.new("Next node undefined. Node: #{current_state.current_node}. Responses: #{responses_and_input}") unless next_node
+        unless @permitted_next_nodes.include?(next_node)
+          raise "Next node (#{next_node}) not in list of permitted next nodes (#{@permitted_next_nodes.to_sentence})"
+        end
         next_node
       end
 
diff --git a/lib/smart_answer_flows/additional-commodity-code.rb b/lib/smart_answer_flows/additional-commodity-code.rb
index d5b3a7c82b3..fafe22c7698 100644
--- a/lib/smart_answer_flows/additional-commodity-code.rb
+++ b/lib/smart_answer_flows/additional-commodity-code.rb
@@ -17,7 +17,14 @@ def define
 
         save_input_as :starch_glucose_weight
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :how_much_sucrose_1?,
+          :how_much_sucrose_2?,
+          :how_much_sucrose_3?,
+          :how_much_sucrose_4?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do |response|
           case response.to_i
           when 25
             :how_much_sucrose_2?
@@ -90,7 +97,16 @@ def define
 
         save_input_as :milk_fat_weight
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :commodity_code_result,
+          :how_much_milk_protein_ab?,
+          :how_much_milk_protein_c?,
+          :how_much_milk_protein_d?,
+          :how_much_milk_protein_ef?,
+          :how_much_milk_protein_gh?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do |response|
           case response.to_i
           when 0, 1
             :how_much_milk_protein_ab?
diff --git a/lib/smart_answer_flows/benefit-cap-calculator.rb b/lib/smart_answer_flows/benefit-cap-calculator.rb
index 20901e11e0c..6a2286cb06e 100644
--- a/lib/smart_answer_flows/benefit-cap-calculator.rb
+++ b/lib/smart_answer_flows/benefit-cap-calculator.rb
@@ -13,7 +13,12 @@ def define
 
         save_input_as :housing_benefit
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :working_tax_credit?,
+          :outcome_not_affected_no_housing_benefit
+        ]
+
+        next_node(permitted: permitted_next_nodes) do |response|
           if response == 'yes'
             :working_tax_credit?
           else
@@ -27,7 +32,12 @@ def define
         option :yes
         option :no
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :outcome_not_affected_exemptions,
+          :receiving_exemption_benefits?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do |response|
           if response == 'yes'
             :outcome_not_affected_exemptions
           else
@@ -41,7 +51,12 @@ def define
         option :yes
         option :no
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :outcome_not_affected_exemptions,
+          :receiving_non_exemption_benefits?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do |response|
           if response == 'yes'
             :outcome_not_affected_exemptions
           else
@@ -84,7 +99,28 @@ def define
           0
         end
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :outcome_not_affected,
+          :bereavement_amount?,
+          :carers_amount?,
+          :child_benefit_amount?,
+          :child_tax_amount?,
+          :esa_amount?,
+          :guardian_amount?,
+          :incapacity_amount?,
+          :income_support_amount?,
+          :jsa_amount?,
+          :maternity_amount?,
+          :sda_amount?,
+          :widow_pension_amount?,
+          :widowed_mother_amount?,
+          :widowed_parent_amount?,
+          :widows_aged_amount?,
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do |response|
           first_value = response.split(",").first
           if response == "none"
             :outcome_not_affected
@@ -101,7 +137,26 @@ def define
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :carers_amount?,
+          :child_benefit_amount?,
+          :child_tax_amount?,
+          :esa_amount?,
+          :guardian_amount?,
+          :incapacity_amount?,
+          :income_support_amount?,
+          :jsa_amount?,
+          :maternity_amount?,
+          :sda_amount?,
+          :widow_pension_amount?,
+          :widowed_mother_amount?,
+          :widowed_parent_amount?,
+          :widows_aged_amount?,
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
@@ -113,7 +168,25 @@ def define
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :child_benefit_amount?,
+          :child_tax_amount?,
+          :esa_amount?,
+          :guardian_amount?,
+          :incapacity_amount?,
+          :income_support_amount?,
+          :jsa_amount?,
+          :maternity_amount?,
+          :sda_amount?,
+          :widow_pension_amount?,
+          :widowed_mother_amount?,
+          :widowed_parent_amount?,
+          :widows_aged_amount?,
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
@@ -125,7 +198,24 @@ def define
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :child_tax_amount?,
+          :esa_amount?,
+          :guardian_amount?,
+          :incapacity_amount?,
+          :income_support_amount?,
+          :jsa_amount?,
+          :maternity_amount?,
+          :sda_amount?,
+          :widow_pension_amount?,
+          :widowed_mother_amount?,
+          :widowed_parent_amount?,
+          :widows_aged_amount?,
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
@@ -137,7 +227,23 @@ def define
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :esa_amount?,
+          :guardian_amount?,
+          :incapacity_amount?,
+          :income_support_amount?,
+          :jsa_amount?,
+          :maternity_amount?,
+          :sda_amount?,
+          :widow_pension_amount?,
+          :widowed_mother_amount?,
+          :widowed_parent_amount?,
+          :widows_aged_amount?,
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
@@ -149,7 +255,22 @@ def define
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :guardian_amount?,
+          :incapacity_amount?,
+          :income_support_amount?,
+          :jsa_amount?,
+          :maternity_amount?,
+          :sda_amount?,
+          :widow_pension_amount?,
+          :widowed_mother_amount?,
+          :widowed_parent_amount?,
+          :widows_aged_amount?,
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
@@ -161,7 +282,21 @@ def define
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :incapacity_amount?,
+          :income_support_amount?,
+          :jsa_amount?,
+          :maternity_amount?,
+          :sda_amount?,
+          :widow_pension_amount?,
+          :widowed_mother_amount?,
+          :widowed_parent_amount?,
+          :widows_aged_amount?,
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
@@ -173,7 +308,20 @@ def define
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :income_support_amount?,
+          :jsa_amount?,
+          :maternity_amount?,
+          :sda_amount?,
+          :widow_pension_amount?,
+          :widowed_mother_amount?,
+          :widowed_parent_amount?,
+          :widows_aged_amount?,
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
@@ -185,7 +333,19 @@ def define
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :jsa_amount?,
+          :maternity_amount?,
+          :sda_amount?,
+          :widow_pension_amount?,
+          :widowed_mother_amount?,
+          :widowed_parent_amount?,
+          :widows_aged_amount?,
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
@@ -197,7 +357,18 @@ def define
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :maternity_amount?,
+          :sda_amount?,
+          :widow_pension_amount?,
+          :widowed_mother_amount?,
+          :widowed_parent_amount?,
+          :widows_aged_amount?,
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
@@ -209,7 +380,17 @@ def define
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :sda_amount?,
+          :widow_pension_amount?,
+          :widowed_mother_amount?,
+          :widowed_parent_amount?,
+          :widows_aged_amount?,
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
@@ -221,43 +402,73 @@ def define
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :widow_pension_amount?,
+          :widowed_mother_amount?,
+          :widowed_parent_amount?,
+          :widows_aged_amount?,
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
 
-      #Q5l
-      money_question :widowed_mother_amount? do
+      #Q5n
+      money_question :widow_pension_amount? do
 
         calculate :total_benefits do |response|
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :widowed_mother_amount?,
+          :widowed_parent_amount?,
+          :widows_aged_amount?,
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
 
-      #Q5m
-      money_question :widowed_parent_amount? do
+      #Q5l
+      money_question :widowed_mother_amount? do
 
         calculate :total_benefits do |response|
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :widowed_parent_amount?,
+          :widows_aged_amount?,
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
 
-      #Q5n
-      money_question :widow_pension_amount? do
+      #Q5m
+      money_question :widowed_parent_amount? do
 
         calculate :total_benefits do |response|
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :widows_aged_amount?,
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
@@ -269,7 +480,12 @@ def define
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :housing_benefit_amount?,
+          :single_couple_lone_parent?
+        ]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
@@ -283,7 +499,9 @@ def define
           total_benefits + response.to_f
         end
 
-        next_node do
+        permitted_next_nodes = [:single_couple_lone_parent?]
+
+        next_node(permitted: permitted_next_nodes) do
           benefit_related_questions.shift
         end
       end
@@ -303,7 +521,12 @@ def define
           sprintf("%.2f", benefit_cap)
         end
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :outcome_affected_greater_than_cap,
+          :outcome_not_affected_less_than_cap
+        ]
+
+        next_node(permitted: permitted_next_nodes) do |response|
           if response == 'single'
             cap = 350
           else
diff --git a/lib/smart_answer_flows/calculate-married-couples-allowance.rb b/lib/smart_answer_flows/calculate-married-couples-allowance.rb
index 5bb8c10d81e..0ec153074d2 100644
--- a/lib/smart_answer_flows/calculate-married-couples-allowance.rb
+++ b/lib/smart_answer_flows/calculate-married-couples-allowance.rb
@@ -60,7 +60,11 @@ def define
 
         validate { |response| response > 0 }
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :paying_into_a_pension?,
+          :husband_done
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           limit = (is_before_april_changes ? 26100.0 : 27000.0)
           if response.to_f >= limit
             :paying_into_a_pension?
@@ -75,7 +79,11 @@ def define
 
         validate { |response| response > 0 }
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :paying_into_a_pension?,
+          :highest_earner_done
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           limit = (is_before_april_changes ? 26100.0 : 27000.0)
           if response.to_f >= limit
             :paying_into_a_pension?
@@ -107,7 +115,11 @@ def define
           calculator.calculate_adjusted_net_income(income.to_f, (gross_pension_contributions.to_f || 0), (net_pension_contributions.to_f || 0), response)
         end
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :husband_done,
+          :highest_earner_done
+        ]
+        next_node(permitted: permitted_next_nodes) do
           if income_measure == "husband"
             :husband_done
           else
diff --git a/lib/smart_answer_flows/calculate-state-pension.rb b/lib/smart_answer_flows/calculate-state-pension.rb
index 470350655a5..a326de2a254 100644
--- a/lib/smart_answer_flows/calculate-state-pension.rb
+++ b/lib/smart_answer_flows/calculate-state-pension.rb
@@ -20,7 +20,11 @@ def define
           SmartAnswer::Calculators::RatesQuery.new('state_pension').rates.weekly_rate
         end
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :dob_bus_pass?,
+          :gender?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           if response == 'bus_pass'
             :dob_bus_pass?
           else
diff --git a/lib/smart_answer_flows/calculate-your-holiday-entitlement.rb b/lib/smart_answer_flows/calculate-your-holiday-entitlement.rb
index 8e673e4a683..0bd585de397 100644
--- a/lib/smart_answer_flows/calculate-your-holiday-entitlement.rb
+++ b/lib/smart_answer_flows/calculate-your-holiday-entitlement.rb
@@ -25,7 +25,13 @@ def define
         option "starting-and-leaving"
         save_input_as :holiday_period
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :what_is_your_starting_date?,
+          :what_is_your_leaving_date?,
+          :how_many_days_per_week?,
+          :how_many_hours_per_week?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           case response
           when "starting", "starting-and-leaving"
             :what_is_your_starting_date?
@@ -52,7 +58,12 @@ def define
         from { Date.civil(1.year.ago.year, 1, 1) }
         to { Date.civil(1.year.since(Date.today).year, 12, 31) }
         save_input_as :start_date
-        next_node do
+
+        permitted_next_nodes = [
+          :what_is_your_leaving_date?,
+          :when_does_your_leave_year_start?
+        ]
+        next_node(permitted: permitted_next_nodes) do
           if holiday_period == "starting-and-leaving"
             :what_is_your_leaving_date?
           else
@@ -67,7 +78,13 @@ def define
         to { Date.civil(1.year.since(Date.today).year, 12, 31) }
         save_input_as :leaving_date
 
-        next_node do
+        permitted_next_nodes = [
+          :how_many_days_per_week?,
+          :how_many_hours_per_week?,
+          :shift_worker_hours_per_shift?,
+          :when_does_your_leave_year_start?
+        ]
+        next_node(permitted: permitted_next_nodes) do
           if holiday_period == "starting-and-leaving"
             case calculation_basis
             when "days-worked-per-week"
@@ -88,7 +105,13 @@ def define
         from { Date.civil(1.year.ago.year, 1, 1) }
         to { Date.civil(1.year.since(Date.today).year, 12, 31) }
         save_input_as :leave_year_start_date
-        next_node do
+
+        permitted_next_nodes = [
+          :how_many_days_per_week?,
+          :how_many_hours_per_week?,
+          :shift_worker_hours_per_shift?
+        ]
+        next_node(permitted: permitted_next_nodes) do
           case calculation_basis
           when "days-worked-per-week"
             :how_many_days_per_week?
diff --git a/lib/smart_answer_flows/check-uk-visa.rb b/lib/smart_answer_flows/check-uk-visa.rb
index 32b3783d4c9..b88a786f35c 100644
--- a/lib/smart_answer_flows/check-uk-visa.rb
+++ b/lib/smart_answer_flows/check-uk-visa.rb
@@ -24,7 +24,12 @@ def define
       country_select :what_passport_do_you_have?, additional_countries: additional_countries, exclude_countries: exclude_countries do
         save_input_as :passport_country
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :israeli_document_type?,
+          :outcome_no_visa_needed,
+          :purpose_of_visit?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           if response == 'israel'
             :israeli_document_type?
           elsif country_group_eea.include?(response)
@@ -40,7 +45,8 @@ def define
         option :"full-passport"
         option :"provisional-passport"
 
-        next_node do |response|
+        permitted_next_nodes = [:purpose_of_visit?]
+        next_node(permitted: permitted_next_nodes) do |response|
           self.passport_country = 'israel-provisional-passport' if response == 'provisional-passport'
           :purpose_of_visit?
         end
diff --git a/lib/smart_answer_flows/childcare-costs-for-tax-credits.rb b/lib/smart_answer_flows/childcare-costs-for-tax-credits.rb
index f1b9d477020..1d4fec59bf5 100644
--- a/lib/smart_answer_flows/childcare-costs-for-tax-credits.rb
+++ b/lib/smart_answer_flows/childcare-costs-for-tax-credits.rb
@@ -66,7 +66,11 @@ def define
           SmartAnswer::Calculators::ChildcareCostCalculator.weekly_cost(response)
         end
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :no_longer_paying,
+          :old_weekly_amount_1?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           amount = Money.new(response)
           amount == 0 ? :no_longer_paying : :old_weekly_amount_1?
         end
@@ -77,7 +81,12 @@ def define
         calculate :weekly_cost do |response|
           SmartAnswer::Calculators::ChildcareCostCalculator.weekly_cost(response)
         end
-        next_node do |response|
+
+        permitted_next_nodes = [
+          :no_longer_paying,
+          :old_weekly_amount_1?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           amount = Money.new(response)
           amount == 0 ? :no_longer_paying : :old_weekly_amount_1?
         end
@@ -146,7 +155,12 @@ def define
         calculate :new_weekly_costs do |response|
           Float(response).ceil
         end
-        next_node do |response|
+
+        permitted_next_nodes = [
+          :no_longer_paying,
+          :old_weekly_amount_2?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           amount = Money.new(response)
           amount == 0 ? :no_longer_paying : :old_weekly_amount_2?
         end
@@ -177,7 +191,11 @@ def define
           SmartAnswer::Calculators::ChildcareCostCalculator.weekly_cost_from_monthly(response)
         end
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :no_longer_paying,
+          :old_weekly_amount_3?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           amount = Money.new(response)
           amount == 0 ? :no_longer_paying : :old_weekly_amount_3?
         end
diff --git a/lib/smart_answer_flows/estimate-self-assessment-penalties.rb b/lib/smart_answer_flows/estimate-self-assessment-penalties.rb
index 7dd2191a503..26bc741de40 100644
--- a/lib/smart_answer_flows/estimate-self-assessment-penalties.rb
+++ b/lib/smart_answer_flows/estimate-self-assessment-penalties.rb
@@ -73,7 +73,8 @@ def define
           filing_date.strftime("%e %B %Y")
         end
 
-        next_node do |response|
+        permitted_next_nodes = [:when_paid?]
+        next_node(permitted: permitted_next_nodes) do |response|
           if response < start_of_next_tax_year
             raise SmartAnswer::InvalidResponse
           else
@@ -88,7 +89,11 @@ def define
 
         save_input_as :payment_date
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :filed_and_paid_on_time,
+          :how_much_tax?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           if filing_date > response
             raise SmartAnswer::InvalidResponse
           else
diff --git a/lib/smart_answer_flows/help-if-you-are-arrested-abroad.rb b/lib/smart_answer_flows/help-if-you-are-arrested-abroad.rb
index 40b5ec9938f..e80bfe6d887 100644
--- a/lib/smart_answer_flows/help-if-you-are-arrested-abroad.rb
+++ b/lib/smart_answer_flows/help-if-you-are-arrested-abroad.rb
@@ -77,7 +77,12 @@ def define
           links
         end
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :answer_two_iran,
+          :answer_three_syria,
+          :answer_one_generic
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           if response == "iran"
             :answer_two_iran
           elsif response == "syria"
diff --git a/lib/smart_answer_flows/landlord-immigration-check.rb b/lib/smart_answer_flows/landlord-immigration-check.rb
index c20a7b988b8..24e92851a51 100644
--- a/lib/smart_answer_flows/landlord-immigration-check.rb
+++ b/lib/smart_answer_flows/landlord-immigration-check.rb
@@ -7,7 +7,11 @@ def define
       satisfies_need "102373"
 
       postcode_question :property? do
-        next_node do |response|
+        permitted_next_nodes = [
+          :main_home?,
+          :outcome_check_not_needed
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           if Calculators::LandlordImmigrationCheckCalculator.valid_postcode(response)
             :main_home?
           else
@@ -20,7 +24,11 @@ def define
         option "yes"
         option "no"
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :tenant_over_18?,
+          :property_type?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           case response
           when "yes"
             :tenant_over_18?
@@ -34,7 +42,11 @@ def define
         option "yes"
         option "no"
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :has_uk_passport?,
+          :outcome_check_not_needed_when_under_18
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           case response
           when "yes"
             :has_uk_passport?
@@ -54,7 +66,17 @@ def define
         option "student_accommodation"
         option "7_year_lease_property"
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :outcome_check_not_needed_if_holiday_or_under_3_months,
+          :outcome_check_not_needed,
+          :outcome_check_not_needed_when_care_home,
+          :outcome_check_not_needed_when_hostel_refuge,
+          :outcome_check_not_needed_when_mobile_home,
+          :outcome_check_not_needed_when_employee_home,
+          :outcome_check_may_be_needed_when_student,
+          :outcome_check_needed_if_break_clause
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           case response
           when "holiday_accommodation"
             :outcome_check_not_needed_if_holiday_or_under_3_months
@@ -80,7 +102,11 @@ def define
         option "yes"
         option "no"
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :outcome_can_rent,
+          :right_to_abode?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           case response
           when "yes"
             :outcome_can_rent
@@ -94,7 +120,11 @@ def define
         option "yes"
         option "no"
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :outcome_can_rent,
+          :has_certificate?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           case response
           when "yes"
             :outcome_can_rent
@@ -108,7 +138,11 @@ def define
         option "yes"
         option "no"
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :outcome_can_rent,
+          :tenant_country?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           case response
           when "yes"
             :outcome_can_rent
@@ -123,7 +157,12 @@ def define
         option "non_eea_but_with_eu_eea_switzerland_family_member"
         option "somewhere_else"
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :has_documents?,
+          :has_residence_card_or_eu_eea_swiss_family_member?,
+          :has_other_documents?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           case response
           when "eu_eea_switzerland"
             :has_documents?
@@ -139,7 +178,11 @@ def define
         option "yes"
         option "no"
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :outcome_can_rent,
+          :has_other_documents?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           case response
           when "yes"
             :outcome_can_rent
@@ -153,7 +196,11 @@ def define
         option "yes"
         option "no"
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :outcome_can_rent,
+          :time_limited_to_remain?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           case response
           when "yes"
             :outcome_can_rent
@@ -167,7 +214,11 @@ def define
         option "yes"
         option "no"
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :outcome_can_rent_for_12_months,
+          :immigration_application?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           case response
           when "yes"
             :outcome_can_rent_for_12_months
@@ -181,7 +232,11 @@ def define
         option "yes"
         option "no"
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :outcome_can_rent_but_check_will_be_needed_again,
+          :has_residence_card_or_eu_eea_swiss_family_member?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           case response
           when "yes"
             :outcome_can_rent_but_check_will_be_needed_again
@@ -195,7 +250,11 @@ def define
         option "yes"
         option "no"
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :outcome_can_rent_for_12_months,
+          :outcome_can_not_rent
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           case response
           when "yes"
             :outcome_can_rent_for_12_months
@@ -209,7 +268,11 @@ def define
         option "yes"
         option "no"
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :outcome_can_rent,
+          :has_asylum_card?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           case response
           when "yes"
             :outcome_can_rent
diff --git a/lib/smart_answer_flows/part-year-profit-tax-credits.rb b/lib/smart_answer_flows/part-year-profit-tax-credits.rb
index 12a64e4ea34..2227794aa41 100644
--- a/lib/smart_answer_flows/part-year-profit-tax-credits.rb
+++ b/lib/smart_answer_flows/part-year-profit-tax-credits.rb
@@ -15,7 +15,8 @@ def define
           Calculators::PartYearProfitTaxCreditsCalculator.new
         end
 
-        next_node do |response|
+        permitted_next_nodes = [:what_date_do_your_accounts_go_up_to?]
+        next_node(permitted: permitted_next_nodes) do |response|
           calculator.tax_credits_award_ends_on = response
           :what_date_do_your_accounts_go_up_to?
         end
@@ -24,7 +25,8 @@ def define
       date_question :what_date_do_your_accounts_go_up_to? do
         default_year { 0 }
 
-        next_node do |response|
+        permitted_next_nodes = [:have_you_stopped_trading?]
+        next_node(permitted: permitted_next_nodes) do |response|
           calculator.accounts_end_month_and_day = response
           :have_you_stopped_trading?
         end
@@ -34,7 +36,11 @@ def define
         option "yes"
         option "no"
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :did_you_start_trading_before_the_relevant_accounting_year?,
+          :do_your_accounts_cover_a_12_month_period?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           if response == 'yes'
             calculator.stopped_trading = true
             :did_you_start_trading_before_the_relevant_accounting_year?
@@ -51,7 +57,11 @@ def define
 
         precalculate(:accounting_year_begins_on) { calculator.accounting_year.begins_on }
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :when_did_you_stop_trading?,
+          :when_did_you_start_trading?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           if response == "yes"
             :when_did_you_stop_trading?
           elsif response == "no"
@@ -71,7 +81,8 @@ def define
           calculator.valid_stopped_trading_date?(response)
         end
 
-        next_node do |response|
+        permitted_next_nodes = [:what_is_your_taxable_profit?]
+        next_node(permitted: permitted_next_nodes) do |response|
           calculator.stopped_trading_on = response
           :what_is_your_taxable_profit?
         end
@@ -83,7 +94,11 @@ def define
 
         precalculate(:accounting_year_ends_on) { calculator.accounting_year.ends_on }
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :what_is_your_taxable_profit?,
+          :when_did_you_start_trading?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           if response == "yes"
             :what_is_your_taxable_profit?
           else
@@ -102,7 +117,11 @@ def define
           calculator.valid_start_trading_date?(response)
         end
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :when_did_you_stop_trading?,
+          :what_is_your_taxable_profit?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           calculator.started_trading_on = response
           if calculator.stopped_trading
             :when_did_you_stop_trading?
@@ -116,7 +135,8 @@ def define
         precalculate(:basis_period_begins_on) { calculator.basis_period.begins_on }
         precalculate(:basis_period_ends_on)   { calculator.basis_period.ends_on }
 
-        next_node do |response|
+        permitted_next_nodes = [:result]
+        next_node(permitted: permitted_next_nodes) do |response|
           calculator.taxable_profit = response
           :result
         end
diff --git a/lib/smart_answer_flows/pip-checker.rb b/lib/smart_answer_flows/pip-checker.rb
index 088f93ec7e8..5539e5fd904 100644
--- a/lib/smart_answer_flows/pip-checker.rb
+++ b/lib/smart_answer_flows/pip-checker.rb
@@ -25,7 +25,15 @@ def define
       date_question :what_is_your_dob? do
         date_of_birth_defaults
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :result_1,
+          :result_2,
+          :result_3,
+          :result_5,
+          :result_6,
+          :result_7
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           calculator.dob = response
           if getting_dla
             if calculator.in_group_65?
diff --git a/lib/smart_answer_flows/report-a-lost-or-stolen-passport.rb b/lib/smart_answer_flows/report-a-lost-or-stolen-passport.rb
index a7e4a7e22b1..012fb4644f4 100644
--- a/lib/smart_answer_flows/report-a-lost-or-stolen-passport.rb
+++ b/lib/smart_answer_flows/report-a-lost-or-stolen-passport.rb
@@ -14,7 +14,11 @@ def define
 
         save_input_as :location
 
-        next_node do
+        permitted_next_nodes = [
+          :complete_LS01_form,
+          :which_country?
+        ]
+        next_node(permitted: permitted_next_nodes) do
           case location
           when 'in_the_uk' then :complete_LS01_form
           when 'abroad' then :which_country?
diff --git a/lib/smart_answer_flows/shared_logic/minimum_wage.rb b/lib/smart_answer_flows/shared_logic/minimum_wage.rb
index f4edf73523e..7cef240a2d8 100644
--- a/lib/smart_answer_flows/shared_logic/minimum_wage.rb
+++ b/lib/smart_answer_flows/shared_logic/minimum_wage.rb
@@ -3,7 +3,12 @@
   option "current_payment"
   option "past_payment"
 
-  next_node do |response|
+  permitted_next_nodes = [
+    :are_you_an_apprentice?,
+    :past_payment_date?
+  ]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     case response
     when 'current_payment'
       :are_you_an_apprentice?
@@ -27,7 +32,9 @@
   option "2009-10-01"
   option "2008-10-01"
 
-  next_node do |response|
+  permitted_next_nodes = [:were_you_an_apprentice?]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     calculator.date = Date.parse(response)
     :were_you_an_apprentice?
   end
@@ -40,7 +47,12 @@
   option "apprentice_over_19_first_year"
   option "apprentice_over_19_second_year_onwards"
 
-  next_node do |response|
+  permitted_next_nodes = [
+    :how_old_are_you?,
+    :how_often_do_you_get_paid?
+  ]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     case response
     when 'not_an_apprentice', 'apprentice_over_19_second_year_onwards'
       calculator.is_apprentice = false
@@ -58,7 +70,13 @@
   option "apprentice_under_19"
   option "apprentice_over_19"
 
-  next_node do |response|
+  permitted_next_nodes = [
+    :how_old_were_you?,
+    :how_often_did_you_get_paid?,
+    :does_not_apply_to_historical_apprentices
+  ]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     case response
     when "no"
       calculator.is_apprentice = false
@@ -80,7 +98,12 @@
     calculator.valid_age?(response)
   end
 
-  next_node do |response|
+  permitted_next_nodes = [
+    :under_school_leaving_age,
+    :how_often_do_you_get_paid?
+  ]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     calculator.age = response
     if calculator.under_school_leaving_age?
       :under_school_leaving_age
@@ -96,7 +119,12 @@
     calculator.valid_age?(response)
   end
 
-  next_node do |response|
+  permitted_next_nodes = [
+    :under_school_leaving_age_past,
+    :how_often_did_you_get_paid?
+  ]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     calculator.age = response
     if calculator.under_school_leaving_age?
       :under_school_leaving_age_past
@@ -112,7 +140,9 @@
     calculator.valid_pay_frequency?(response)
   end
 
-  next_node do |response|
+  permitted_next_nodes = [:how_many_hours_do_you_work?]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     calculator.pay_frequency = response
     :how_many_hours_do_you_work?
   end
@@ -124,7 +154,9 @@
     calculator.valid_pay_frequency?(response)
   end
 
-  next_node do |response|
+  permitted_next_nodes = [:how_many_hours_did_you_work?]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     calculator.pay_frequency = response
     :how_many_hours_did_you_work?
   end
@@ -136,7 +168,9 @@
     calculator.valid_hours_worked?(response)
   end
 
-  next_node do |response|
+  permitted_next_nodes = [:how_much_are_you_paid_during_pay_period?]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     calculator.basic_hours = response
     :how_much_are_you_paid_during_pay_period?
   end
@@ -148,7 +182,9 @@
     calculator.valid_hours_worked?(response)
   end
 
-  next_node do |response|
+  permitted_next_nodes = [:how_much_were_you_paid_during_pay_period?]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     calculator.basic_hours = response
     :how_much_were_you_paid_during_pay_period?
   end
@@ -156,7 +192,9 @@
 
 # Q6
 money_question :how_much_are_you_paid_during_pay_period? do
-  next_node do |response|
+  permitted_next_nodes = [:how_many_hours_overtime_do_you_work?]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     calculator.basic_pay = Float(response)
     :how_many_hours_overtime_do_you_work?
   end
@@ -164,7 +202,9 @@
 
 # Q6 Past
 money_question :how_much_were_you_paid_during_pay_period? do
-  next_node do |response|
+  permitted_next_nodes = [:how_many_hours_overtime_did_you_work?]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     calculator.basic_pay = Float(response)
     :how_many_hours_overtime_did_you_work?
   end
@@ -176,7 +216,12 @@
     calculator.valid_overtime_hours_worked?(response)
   end
 
-  next_node do |response|
+  permitted_next_nodes = [
+    :what_is_overtime_pay_per_hour?,
+    :is_provided_with_accommodation?
+  ]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     calculator.overtime_hours = response
     if calculator.any_overtime_hours_worked?
       :what_is_overtime_pay_per_hour?
@@ -192,7 +237,12 @@
     calculator.valid_overtime_hours_worked?(response)
   end
 
-  next_node do |response|
+  permitted_next_nodes = [
+    :what_was_overtime_pay_per_hour?,
+    :was_provided_with_accommodation?
+  ]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     calculator.overtime_hours = response
     if calculator.any_overtime_hours_worked?
       :what_was_overtime_pay_per_hour?
@@ -204,7 +254,9 @@
 
 # Q8
 money_question :what_is_overtime_pay_per_hour? do
-  next_node do |response|
+  permitted_next_nodes = [:is_provided_with_accommodation?]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     calculator.overtime_hourly_rate = Float(response)
     :is_provided_with_accommodation?
   end
@@ -212,7 +264,9 @@
 
 # Q8 Past
 money_question :what_was_overtime_pay_per_hour? do
-  next_node do |response|
+  permitted_next_nodes = [:was_provided_with_accommodation?]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     calculator.overtime_hourly_rate = Float(response)
     :was_provided_with_accommodation?
   end
@@ -224,7 +278,14 @@
   option "yes_free"
   option "yes_charged"
 
-  next_node do |response|
+  permitted_next_nodes = [
+    :current_accommodation_usage?,
+    :current_accommodation_charge?,
+    :current_payment_above,
+    :current_payment_below
+  ]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     case response
     when "yes_free"
       :current_accommodation_usage?
@@ -246,7 +307,14 @@
   option "yes_free"
   option "yes_charged"
 
-  next_node do |response|
+  permitted_next_nodes = [
+    :past_accommodation_usage?,
+    :past_accommodation_charge?,
+    :past_payment_above,
+    :past_payment_below
+  ]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     case response
     when "yes_free"
       :past_accommodation_usage?
@@ -290,7 +358,12 @@
     calculator.valid_accommodation_usage?(response)
   end
 
-  next_node do |response|
+  permitted_next_nodes = [
+    :current_payment_above,
+    :current_payment_below
+  ]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     calculator.accommodation_adjustment(accommodation_charge, response)
     if calculator.minimum_wage_or_above?
       :current_payment_above
@@ -306,7 +379,12 @@
     calculator.valid_accommodation_usage?(response)
   end
 
-  next_node do |response|
+  permitted_next_nodes = [
+    :past_payment_above,
+    :past_payment_below
+  ]
+
+  next_node(permitted: permitted_next_nodes) do |response|
     calculator.accommodation_adjustment(accommodation_charge, response)
     if calculator.historically_receiving_minimum_wage?
       :past_payment_above
diff --git a/lib/smart_answer_flows/shared_logic/redundancy_pay.rb b/lib/smart_answer_flows/shared_logic/redundancy_pay.rb
index 45ea87300fc..478331d1aa8 100644
--- a/lib/smart_answer_flows/shared_logic/redundancy_pay.rb
+++ b/lib/smart_answer_flows/shared_logic/redundancy_pay.rb
@@ -49,7 +49,11 @@
     raise InvalidResponse if ye.to_i > years_available
     ye
   end
-  next_node do |response|
+  permitted_next_nodes = [
+    :done_no_statutory,
+    :weekly_pay_before_tax?
+  ]
+  next_node(permitted: permitted_next_nodes) do |response|
     if response.floor < 2
       :done_no_statutory
     else
@@ -79,7 +83,11 @@
     calculator.number_of_weeks_entitlement
   end
 
-  next_node do |response|
+  permitted_next_nodes = [
+    :done_no_statutory,
+    :done
+  ]
+  next_node(permitted: permitted_next_nodes) do
     if years_employed < 2
       :done_no_statutory
     else
diff --git a/lib/smart_answer_flows/simplified-expenses-checker.rb b/lib/smart_answer_flows/simplified-expenses-checker.rb
index fde88103786..7727ecd7ed3 100644
--- a/lib/smart_answer_flows/simplified-expenses-checker.rb
+++ b/lib/smart_answer_flows/simplified-expenses-checker.rb
@@ -35,7 +35,13 @@ def define
           response == "none" ? [] : response.split(",")
         end
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :you_cant_use_result,
+          :buying_new_vehicle?,
+          :hours_work_home?,
+          :deduct_from_premises?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           next_question = nil
           if response == "none"
             :you_cant_use_result
@@ -58,7 +64,12 @@ def define
         option :yes
         option :no
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :is_vehicle_green?,
+          :capital_allowances?,
+          :how_much_expect_to_claim?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           if response == "yes"
             :is_vehicle_green?
           else
@@ -86,7 +97,13 @@ def define
           response == "yes" and (list_of_expenses & %w(using_home_for_business live_on_business_premises)).any?
         end
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :hours_work_home?,
+          :deduct_from_premises?,
+          :capital_allowance_result,
+          :how_much_expect_to_claim?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           if response == "yes"
             if (list_of_expenses & %w(using_home_for_business live_on_business_premises)).any?
               if list_of_expenses.include?("using_home_for_business")
@@ -110,7 +127,11 @@ def define
       money_question :how_much_expect_to_claim? do
         save_input_as :vehicle_costs
 
-        next_node do
+        permitted_next_nodes = [
+          :drive_business_miles_car_van?,
+          :drive_business_miles_motorcycle?
+        ]
+        next_node(permitted: permitted_next_nodes) do
           if list_of_expenses.include?("car_or_van")
             :drive_business_miles_car_van?
           else
@@ -167,7 +188,11 @@ def define
           vehicle_is_green ? nil : Money.new(dirty_vehicle_price * ( business_use_percent / 100))
         end
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :drive_business_miles_car_van?,
+          :drive_business_miles_motorcycle?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           raise InvalidResponse if response.to_i > 100
           list_of_expenses.include?("car_or_van") ?
             :drive_business_miles_car_van? : :drive_business_miles_motorcycle?
@@ -188,7 +213,14 @@ def define
             Money.new(4500.0 + answer_over_amount)
           end
         end
-        next_node do
+
+        permitted_next_nodes = [
+          :drive_business_miles_motorcycle?,
+          :hours_work_home?,
+          :deduct_from_premises?,
+          :you_can_use_result
+        ]
+        next_node(permitted: permitted_next_nodes) do
           if list_of_expenses.include?("motorcycle")
             :drive_business_miles_motorcycle?
           elsif list_of_expenses.include?("using_home_for_business")
@@ -206,7 +238,13 @@ def define
         calculate :simple_motorcycle_costs do |response|
           Money.new(response.gsub(",", "").to_f * 0.24)
         end
-        next_node do
+
+        permitted_next_nodes = [
+          :hours_work_home?,
+          :deduct_from_premises?,
+          :you_can_use_result
+        ]
+        next_node(permitted: permitted_next_nodes) do
           if list_of_expenses.include?("using_home_for_business")
             :hours_work_home?
           elsif list_of_expenses.include?("live_on_business_premises")
@@ -234,7 +272,11 @@ def define
           Money.new(amount)
         end
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :you_cant_use_result,
+          :current_claim_amount_home?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           hours = response.to_i
           if hours < 1
             raise SmartAnswer::InvalidResponse
@@ -250,7 +292,11 @@ def define
       money_question :current_claim_amount_home? do
         save_input_as :home_costs
 
-        next_node do
+        permitted_next_nodes = [
+          :deduct_from_premises?,
+          :you_can_use_result
+        ]
+        next_node(permitted: permitted_next_nodes) do
           list_of_expenses.include?("live_on_business_premises") ? :deduct_from_premises? : :you_can_use_result
         end
 
diff --git a/lib/smart_answer_flows/student-finance-calculator.rb b/lib/smart_answer_flows/student-finance-calculator.rb
index e0aed76357e..ec07bf5c730 100644
--- a/lib/smart_answer_flows/student-finance-calculator.rb
+++ b/lib/smart_answer_flows/student-finance-calculator.rb
@@ -38,7 +38,12 @@ def define
           Money.new(response)
         end
 
-        next_node do
+        permitted_next_nodes = [
+          :where_will_you_live_while_studying?,
+          :do_any_of_the_following_apply_all_uk_students?,
+          :outcome_eu_students
+        ]
+        next_node(permitted: permitted_next_nodes) do
           case course_type
           when 'uk-full-time'
             :where_will_you_live_while_studying?
@@ -119,7 +124,12 @@ def define
 
         save_input_as :course_studied
 
-        next_node do
+        permitted_next_nodes = [
+          :outcome_uk_full_time_students,
+          :outcome_uk_all_students,
+          :outcome_eu_students
+        ]
+        next_node(permitted: permitted_next_nodes) do
           case course_type
           when 'uk-full-time'
             :outcome_uk_full_time_students
diff --git a/test/data/additional-commodity-code-files.yml b/test/data/additional-commodity-code-files.yml
index 9942d07f0e6..42553ca5929 100644
--- a/test/data/additional-commodity-code-files.yml
+++ b/test/data/additional-commodity-code-files.yml
@@ -1,5 +1,5 @@
 ---
-lib/smart_answer_flows/additional-commodity-code.rb: a824498493048a251eefac4c2cbc97fb
+lib/smart_answer_flows/additional-commodity-code.rb: 3408534464ca7ba7317bb02f73497f2e
 lib/smart_answer_flows/locales/en/additional-commodity-code.yml: 417fd0ca1fc4cfb449d334e8c03c0622
 test/data/additional-commodity-code-questions-and-responses.yml: f2149cbfa6ec8c5ead572f0a89542a79
 test/data/additional-commodity-code-responses-and-expected-results.yml: 6ca51c22f472dbe159ac81f31006a7b1
diff --git a/test/data/am-i-getting-minimum-wage-files.yml b/test/data/am-i-getting-minimum-wage-files.yml
index 1ad4b804600..1d488861662 100644
--- a/test/data/am-i-getting-minimum-wage-files.yml
+++ b/test/data/am-i-getting-minimum-wage-files.yml
@@ -12,6 +12,6 @@ lib/smart_answer_flows/am-i-getting-minimum-wage/past_payment_below.govspeak.erb
 lib/smart_answer_flows/am-i-getting-minimum-wage/under_school_leaving_age.govspeak.erb: 44bf68757d1ef90249d19f5d88ad4bc2
 lib/smart_answer_flows/am-i-getting-minimum-wage/under_school_leaving_age_past.govspeak.erb: 2182c103915b753894722760c9a56cf3
 lib/smart_answer_flows/shared/minimum_wage/_acas_information.govspeak.erb: 0d2f7c4d01e3c928701e7d649663707e
-lib/smart_answer_flows/shared_logic/minimum_wage.rb: a92ebb84563f1f6d8f85e0d6ededa868
+lib/smart_answer_flows/shared_logic/minimum_wage.rb: 434cb45cdd375590238a8097d34ce987
 lib/smart_answer/calculators/minimum_wage_calculator.rb: cab354bb2fc0f660d6c6aef70b9fabc5
 lib/data/minimum_wage_data.yml: 3feed11191d68237289203a2c659ecf9
diff --git a/test/data/benefit-cap-calculator-files.yml b/test/data/benefit-cap-calculator-files.yml
index d8673aeacbf..b07555b8a8c 100644
--- a/test/data/benefit-cap-calculator-files.yml
+++ b/test/data/benefit-cap-calculator-files.yml
@@ -1,5 +1,5 @@
 ---
-lib/smart_answer_flows/benefit-cap-calculator.rb: acc7833e5ea23ff3349753991fb6bb1e
+lib/smart_answer_flows/benefit-cap-calculator.rb: 3272eb6344567f88ec75694fc1d4b7d6
 lib/smart_answer_flows/locales/en/benefit-cap-calculator.yml: f529cf71d32a7e802454eb79244a0a36
 test/data/benefit-cap-calculator-questions-and-responses.yml: 460336f2cf1f2acc62729ef5d831f25e
 test/data/benefit-cap-calculator-responses-and-expected-results.yml: 19c0bc207cde0d94c76b769b0da5d0bd
diff --git a/test/data/calculate-employee-redundancy-pay-files.yml b/test/data/calculate-employee-redundancy-pay-files.yml
index 7d08ee3dd3a..fe4247b8116 100644
--- a/test/data/calculate-employee-redundancy-pay-files.yml
+++ b/test/data/calculate-employee-redundancy-pay-files.yml
@@ -6,7 +6,7 @@ test/data/calculate-employee-redundancy-pay-responses-and-expected-results.yml:
 lib/smart_answer_flows/calculate-employee-redundancy-pay/calculate_employee_redundancy_pay.govspeak.erb: 22dbc473918685ceb57b7a2a87b6fe47
 lib/smart_answer_flows/calculate-employee-redundancy-pay/done.govspeak.erb: 87c7dfc2a59723966e585ef0c2c66b47
 lib/smart_answer_flows/calculate-employee-redundancy-pay/done_no_statutory.govspeak.erb: 446e959e823c5e4631e86de58f9f0349
-lib/smart_answer_flows/shared_logic/redundancy_pay.rb: ec40180eb9c26b00736173986375d60c
+lib/smart_answer_flows/shared_logic/redundancy_pay.rb: 2e1a5aeacda3efca59b18efecb256e58
 lib/smart_answer/calculators/redundancy_calculator.rb: 6f97d315c840f829670f64e2fabce6dd
 lib/data/rates/redundancy_pay.yml: 270b43298e223b28ba7ad3f81f5e0a08
 lib/data/rates/redundancy_pay_northern_ireland.yml: 01a56e2760328e0213318050689f2556
diff --git a/test/data/calculate-married-couples-allowance-files.yml b/test/data/calculate-married-couples-allowance-files.yml
index 7a60fd681cc..8d8356b28cb 100644
--- a/test/data/calculate-married-couples-allowance-files.yml
+++ b/test/data/calculate-married-couples-allowance-files.yml
@@ -1,5 +1,5 @@
 ---
-lib/smart_answer_flows/calculate-married-couples-allowance.rb: 3d7bce5378b53ef23680c2f84c2a3459
+lib/smart_answer_flows/calculate-married-couples-allowance.rb: 45b0a1885607ee65b9261b93588e3ed9
 lib/smart_answer_flows/locales/en/calculate-married-couples-allowance.yml: d3000af873a9c53b2f62719b3d72e91d
 test/data/calculate-married-couples-allowance-questions-and-responses.yml: 1bbef5f2f30d470433bbb63f029881cd
 test/data/calculate-married-couples-allowance-responses-and-expected-results.yml: 3bb53e4211718b8b1b7dacfaa52f3f49
diff --git a/test/data/calculate-state-pension-files.yml b/test/data/calculate-state-pension-files.yml
index 905eb471486..1bb808c2851 100644
--- a/test/data/calculate-state-pension-files.yml
+++ b/test/data/calculate-state-pension-files.yml
@@ -1,5 +1,5 @@
 ---
-lib/smart_answer_flows/calculate-state-pension.rb: a67c7e878b421309f2ed1e56de34c73a
+lib/smart_answer_flows/calculate-state-pension.rb: e8b8b7363972770943c39dd3bfeb2158
 lib/smart_answer_flows/locales/en/calculate-state-pension.yml: 59b2577b5bd537db695a998d82264e7e
 test/data/calculate-state-pension-questions-and-responses.yml: 8fe4d28d6b90ff1030ed15470d5b458f
 test/data/calculate-state-pension-responses-and-expected-results.yml: 61e8ccba31841f6616cf8b26f3da6ff9
diff --git a/test/data/calculate-your-holiday-entitlement-files.yml b/test/data/calculate-your-holiday-entitlement-files.yml
index 03ef404f7fe..4490557e33d 100644
--- a/test/data/calculate-your-holiday-entitlement-files.yml
+++ b/test/data/calculate-your-holiday-entitlement-files.yml
@@ -1,5 +1,5 @@
 ---
-lib/smart_answer_flows/calculate-your-holiday-entitlement.rb: 6eec1440f4fc73734fb4d5a40861fbea
+lib/smart_answer_flows/calculate-your-holiday-entitlement.rb: 2285f098692e763af45dc824079b12a5
 lib/smart_answer_flows/locales/en/calculate-your-holiday-entitlement.yml: 0e0af2f45c9cca757b9d5fcb6fd3cc6d
 test/data/calculate-your-holiday-entitlement-questions-and-responses.yml: a5d687911e6173e74f2b70af6a5ff7bd
 test/data/calculate-your-holiday-entitlement-responses-and-expected-results.yml: b7d4735ae33ef0dceeeb97c12019db84
diff --git a/test/data/calculate-your-redundancy-pay-files.yml b/test/data/calculate-your-redundancy-pay-files.yml
index 8d5847fe7b6..e1c90f4a589 100644
--- a/test/data/calculate-your-redundancy-pay-files.yml
+++ b/test/data/calculate-your-redundancy-pay-files.yml
@@ -6,7 +6,7 @@ test/data/calculate-your-redundancy-pay-responses-and-expected-results.yml: c2a4
 lib/smart_answer_flows/calculate-your-redundancy-pay/calculate_your_redundancy_pay.govspeak.erb: 063d747da3117bc0e06d271bd78bbe88
 lib/smart_answer_flows/calculate-your-redundancy-pay/done.govspeak.erb: 627ae9150dfcf72d8294f9f68019ba91
 lib/smart_answer_flows/calculate-your-redundancy-pay/done_no_statutory.govspeak.erb: e4f6b40f10295e4757075ff698b39707
-lib/smart_answer_flows/shared_logic/redundancy_pay.rb: ec40180eb9c26b00736173986375d60c
+lib/smart_answer_flows/shared_logic/redundancy_pay.rb: 2e1a5aeacda3efca59b18efecb256e58
 lib/smart_answer/calculators/redundancy_calculator.rb: 6f97d315c840f829670f64e2fabce6dd
 lib/data/rates/redundancy_pay.yml: 270b43298e223b28ba7ad3f81f5e0a08
 lib/data/rates/redundancy_pay_northern_ireland.yml: 01a56e2760328e0213318050689f2556
diff --git a/test/data/check-uk-visa-files.yml b/test/data/check-uk-visa-files.yml
index b4ff7902cbb..deb052852ad 100644
--- a/test/data/check-uk-visa-files.yml
+++ b/test/data/check-uk-visa-files.yml
@@ -1,5 +1,5 @@
 ---
-lib/smart_answer_flows/check-uk-visa.rb: 65e37027d0c5c4541dc7d8d60f54b741
+lib/smart_answer_flows/check-uk-visa.rb: 31e8f3fd00c2c3dd84cfbedc62893d27
 lib/smart_answer_flows/locales/en/check-uk-visa.yml: a8c595b226b52e2c9b5d7b32723fbdb2
 test/data/check-uk-visa-questions-and-responses.yml: b77c21b505c201c2014e17e13d52b5a0
 test/data/check-uk-visa-responses-and-expected-results.yml: 603a0b14f2a49a20d01cc4b959fb90b7
diff --git a/test/data/childcare-costs-for-tax-credits-files.yml b/test/data/childcare-costs-for-tax-credits-files.yml
index 0616ef0880d..29f2a11b1f3 100644
--- a/test/data/childcare-costs-for-tax-credits-files.yml
+++ b/test/data/childcare-costs-for-tax-credits-files.yml
@@ -1,5 +1,5 @@
 ---
-lib/smart_answer_flows/childcare-costs-for-tax-credits.rb: 2c5d3e00ecce939574dfa9663bf478f8
+lib/smart_answer_flows/childcare-costs-for-tax-credits.rb: b51523114c809685a8b01e8daf0fa7e6
 lib/smart_answer_flows/locales/en/childcare-costs-for-tax-credits.yml: 1f9c5671b17aa97b6ea2472634481997
 test/data/childcare-costs-for-tax-credits-questions-and-responses.yml: 136aea3591662aa753c3c630546e68ad
 test/data/childcare-costs-for-tax-credits-responses-and-expected-results.yml: 7d90f3446d1e2c9551d7d363fbc4d639
diff --git a/test/data/estimate-self-assessment-penalties-files.yml b/test/data/estimate-self-assessment-penalties-files.yml
index 352249b8c71..2acac60cea3 100644
--- a/test/data/estimate-self-assessment-penalties-files.yml
+++ b/test/data/estimate-self-assessment-penalties-files.yml
@@ -1,5 +1,5 @@
 ---
-lib/smart_answer_flows/estimate-self-assessment-penalties.rb: c097850300a0c888c26552870b32cb66
+lib/smart_answer_flows/estimate-self-assessment-penalties.rb: 86a215cfbee1a7af475243bc10e7c1fa
 lib/smart_answer_flows/locales/en/estimate-self-assessment-penalties.yml: 97c0cf1ea0ce03f9012ff60ec5a02559
 test/data/estimate-self-assessment-penalties-questions-and-responses.yml: 186d93854ea5dc9321408e14dcc8d61f
 test/data/estimate-self-assessment-penalties-responses-and-expected-results.yml: 07a0cd26b8c5e4b1fff6dfe51c20142e
diff --git a/test/data/help-if-you-are-arrested-abroad-files.yml b/test/data/help-if-you-are-arrested-abroad-files.yml
index 2eb57c2a965..acefa861858 100644
--- a/test/data/help-if-you-are-arrested-abroad-files.yml
+++ b/test/data/help-if-you-are-arrested-abroad-files.yml
@@ -1,5 +1,5 @@
 ---
-lib/smart_answer_flows/help-if-you-are-arrested-abroad.rb: 0d1e142d0929429219421fcab1260616
+lib/smart_answer_flows/help-if-you-are-arrested-abroad.rb: cc7831e704176ed0a3545425c6e08f2e
 lib/smart_answer_flows/locales/en/help-if-you-are-arrested-abroad.yml: 8dbb908db1cb70bdf47c166d127a3703
 test/data/help-if-you-are-arrested-abroad-questions-and-responses.yml: c007b0dd259d1c09ccc2dd3163fa1e56
 test/data/help-if-you-are-arrested-abroad-responses-and-expected-results.yml: 26a4d487258c3984a6cd73da22c2d8e6
diff --git a/test/data/landlord-immigration-check-files.yml b/test/data/landlord-immigration-check-files.yml
index 5dd2879403e..9fbd9602fe9 100644
--- a/test/data/landlord-immigration-check-files.yml
+++ b/test/data/landlord-immigration-check-files.yml
@@ -1,5 +1,5 @@
 ---
-lib/smart_answer_flows/landlord-immigration-check.rb: f87297c9c751e8cd5410155fe864712a
+lib/smart_answer_flows/landlord-immigration-check.rb: 2eaabee434804a3f31b17a275a84f368
 lib/smart_answer_flows/locales/en/landlord-immigration-check.yml: 590064bf90819fb8cc0484d7c46d0261
 test/data/landlord-immigration-check-questions-and-responses.yml: 7259b20b404af56667915a12e43d6da0
 test/data/landlord-immigration-check-responses-and-expected-results.yml: 329e7752e670f0ee92bc1c671ba478a7
diff --git a/test/data/minimum-wage-calculator-employers-files.yml b/test/data/minimum-wage-calculator-employers-files.yml
index cd59ab8ac7b..dc0e86d7295 100644
--- a/test/data/minimum-wage-calculator-employers-files.yml
+++ b/test/data/minimum-wage-calculator-employers-files.yml
@@ -12,6 +12,6 @@ lib/smart_answer_flows/minimum-wage-calculator-employers/past_payment_below.govs
 lib/smart_answer_flows/minimum-wage-calculator-employers/under_school_leaving_age.govspeak.erb: 13de5d10bbbb015df597f78c66da1b67
 lib/smart_answer_flows/minimum-wage-calculator-employers/under_school_leaving_age_past.govspeak.erb: 9c56f76e04984f07627efbc1f42b2b63
 lib/smart_answer_flows/shared/minimum_wage/_acas_information.govspeak.erb: 0d2f7c4d01e3c928701e7d649663707e
-lib/smart_answer_flows/shared_logic/minimum_wage.rb: a92ebb84563f1f6d8f85e0d6ededa868
+lib/smart_answer_flows/shared_logic/minimum_wage.rb: 434cb45cdd375590238a8097d34ce987
 lib/smart_answer/calculators/minimum_wage_calculator.rb: cab354bb2fc0f660d6c6aef70b9fabc5
 lib/data/minimum_wage_data.yml: 3feed11191d68237289203a2c659ecf9
diff --git a/test/data/pip-checker-files.yml b/test/data/pip-checker-files.yml
index 7ae6cb31e86..c9fce84c922 100644
--- a/test/data/pip-checker-files.yml
+++ b/test/data/pip-checker-files.yml
@@ -1,5 +1,5 @@
 ---
-lib/smart_answer_flows/pip-checker.rb: d1e6a1262d11e9413a43f4173462a174
+lib/smart_answer_flows/pip-checker.rb: f6dcb2c011e67ec01133aa7d2f57f969
 lib/smart_answer_flows/locales/en/pip-checker.yml: 726e0dd42e3505341c9bfc7e4888d4a5
 test/data/pip-checker-questions-and-responses.yml: b1d68ebfb76a9e2793705c55b82294f5
 test/data/pip-checker-responses-and-expected-results.yml: a2c772b69a493d1844cfa32681057796
diff --git a/test/data/report-a-lost-or-stolen-passport-files.yml b/test/data/report-a-lost-or-stolen-passport-files.yml
index 59b176fe06e..93f3cecbef6 100644
--- a/test/data/report-a-lost-or-stolen-passport-files.yml
+++ b/test/data/report-a-lost-or-stolen-passport-files.yml
@@ -1,5 +1,5 @@
 ---
-lib/smart_answer_flows/report-a-lost-or-stolen-passport.rb: 6451dcf9cd6a29df60f3d272ce20d808
+lib/smart_answer_flows/report-a-lost-or-stolen-passport.rb: 6fd91372c8982473b857f57cb6b4e540
 lib/smart_answer_flows/locales/en/report-a-lost-or-stolen-passport.yml: b3b8d31d025f554b1589e8c33fdd8c15
 test/data/report-a-lost-or-stolen-passport-questions-and-responses.yml: cb7d64407b737eeb4924389f3bd335c6
 test/data/report-a-lost-or-stolen-passport-responses-and-expected-results.yml: 2ef8837f76907e72aadb198636a62078
diff --git a/test/data/simplified-expenses-checker-files.yml b/test/data/simplified-expenses-checker-files.yml
index f088444d4a2..07d15c1feb7 100644
--- a/test/data/simplified-expenses-checker-files.yml
+++ b/test/data/simplified-expenses-checker-files.yml
@@ -1,5 +1,5 @@
 ---
-lib/smart_answer_flows/simplified-expenses-checker.rb: 9f175300a38da904bee8bfacb26af032
+lib/smart_answer_flows/simplified-expenses-checker.rb: 08c2a1ffb98fac5e69533e1bdd0b373b
 lib/smart_answer_flows/locales/en/simplified-expenses-checker.yml: ae340f0f515377411d8710468afa4962
 test/data/simplified-expenses-checker-questions-and-responses.yml: 6b1c358b3730897b6cbefa9477ada15b
 test/data/simplified-expenses-checker-responses-and-expected-results.yml: 983e72657f76697beafb2dcbe4018bee
diff --git a/test/data/student-finance-calculator-files.yml b/test/data/student-finance-calculator-files.yml
index 7058bc7f101..7104ff9e40b 100644
--- a/test/data/student-finance-calculator-files.yml
+++ b/test/data/student-finance-calculator-files.yml
@@ -1,5 +1,5 @@
 ---
-lib/smart_answer_flows/student-finance-calculator.rb: 3235722e11f9cd2ef9d2b29ea988c453
+lib/smart_answer_flows/student-finance-calculator.rb: 7dad8190af5f892d12312b7f9ad30d32
 lib/smart_answer_flows/locales/en/student-finance-calculator.yml: c1c56f850e993f1b7dd48964ae268292
 test/data/student-finance-calculator-questions-and-responses.yml: 8f68ec47644191cd01864ba288acf7ec
 test/data/student-finance-calculator-responses-and-expected-results.yml: 4d17ae39630843d360460ef2131c5980
diff --git a/test/fixtures/graph_presenter_test/graph.rb b/test/fixtures/graph_presenter_test/graph.rb
index c515b894e75..3ee465dea95 100644
--- a/test/fixtures/graph_presenter_test/graph.rb
+++ b/test/fixtures/graph_presenter_test/graph.rb
@@ -13,9 +13,9 @@ def define
         option :a
         option :b
 
-        permitted_next_nodes :done_a, :done_b
+        permitted_next_nodes = [:done_a, :done_b]
 
-        next_node do |response|
+        next_node(permitted: permitted_next_nodes) do |response|
           if response == 'a'
             :done_a
           else
diff --git a/test/fixtures/graph_presenter_test/missing_transition.rb b/test/fixtures/graph_presenter_test/missing_transition.rb
deleted file mode 100644
index eb7e7a27ede..00000000000
--- a/test/fixtures/graph_presenter_test/missing_transition.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-module SmartAnswer
-  class MissingTransitionFlow < Flow
-    def define
-      name 'missing-transition'
-      status :draft
-
-      multiple_choice :q1? do
-        option :yes
-        option :no
-
-        next_node do
-          :done
-        end
-      end
-
-      outcome :done
-    end
-  end
-end
diff --git a/test/fixtures/smart_answer_flows/bridge-of-death.rb b/test/fixtures/smart_answer_flows/bridge-of-death.rb
index 28320015474..8156a79f651 100644
--- a/test/fixtures/smart_answer_flows/bridge-of-death.rb
+++ b/test/fixtures/smart_answer_flows/bridge-of-death.rb
@@ -14,7 +14,11 @@ def define
         option :to_rescue_the_princess
         option :dunno
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :what_is_the_capital_of_assyria?,
+          :what_is_your_favorite_colour?
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           if your_name =~ /robin/i and response == 'to_seek_the_holy_grail'
             :what_is_the_capital_of_assyria?
           else
diff --git a/test/fixtures/smart_answer_flows/checkbox-sample.rb b/test/fixtures/smart_answer_flows/checkbox-sample.rb
index 601d0822ff3..979d24966e3 100644
--- a/test/fixtures/smart_answer_flows/checkbox-sample.rb
+++ b/test/fixtures/smart_answer_flows/checkbox-sample.rb
@@ -12,7 +12,12 @@ def define
 
         save_input_as :toppings
 
-        next_node do |response|
+        permitted_next_nodes = [
+          :margherita,
+          :no_way,
+          :on_its_way
+        ]
+        next_node(permitted: permitted_next_nodes) do |response|
           if response == 'none'
             :margherita
           else
diff --git a/test/fixtures/smart_answer_flows/custom-errors-sample.rb b/test/fixtures/smart_answer_flows/custom-errors-sample.rb
index e9028c52312..d03805cbf2e 100644
--- a/test/fixtures/smart_answer_flows/custom-errors-sample.rb
+++ b/test/fixtures/smart_answer_flows/custom-errors-sample.rb
@@ -5,7 +5,7 @@ def define
       status :draft
 
       value_question :how_many_things_do_you_own? do
-        next_node do |response|
+        next_node(permitted: [:done]) do |response|
           raise SmartAnswer::InvalidResponse, :custom_error unless response.to_i > 0
           :done
         end
diff --git a/test/unit/graph_presenter_test.rb b/test/unit/graph_presenter_test.rb
index d57d35e33fb..2df7d88dfde 100644
--- a/test/unit/graph_presenter_test.rb
+++ b/test/unit/graph_presenter_test.rb
@@ -2,7 +2,6 @@
 require_relative '../helpers/i18n_test_helper'
 
 require 'fixtures/graph_presenter_test/graph'
-require 'fixtures/graph_presenter_test/missing_transition'
 
 module SmartAnswer
   class GraphPresenterTest < ActiveSupport::TestCase
@@ -43,9 +42,6 @@ class GraphPresenterTest < ActiveSupport::TestCase
     test "indicates does not define transitions in a way which can be visualised" do
       p = GraphPresenter.new(SmartAnswer::GraphFlow.build)
       assert p.visualisable?, "'graph' should be visualisable"
-
-      p = GraphPresenter.new(SmartAnswer::MissingTransitionFlow.build)
-      refute p.visualisable?, "'missing_transition' should not be visualisable"
     end
   end
 end
diff --git a/test/unit/multiple_choice_question_test.rb b/test/unit/multiple_choice_question_test.rb
index 1ba3c2fac5a..2174b7a0adc 100644
--- a/test/unit/multiple_choice_question_test.rb
+++ b/test/unit/multiple_choice_question_test.rb
@@ -38,8 +38,7 @@ class MultipleChoiceQuestionTest < ActiveSupport::TestCase
       q = Question::MultipleChoice.new(nil, :example) do
         option yes: :fred
         option :no
-        next_node { :baz }
-        permitted_next_nodes(:baz)
+        next_node(permitted: [:baz]) { :baz }
       end
 
       new_state = q.transition(State.new(:example), :no)
diff --git a/test/unit/question_base_test.rb b/test/unit/question_base_test.rb
index 5d1d7d948d3..7d8c6bab3ea 100644
--- a/test/unit/question_base_test.rb
+++ b/test/unit/question_base_test.rb
@@ -3,6 +3,29 @@
 require_relative '../test_helper'
 
 class QuestionBaseTest < ActiveSupport::TestCase
+  test "#next_node_for raises an exception when the next node isn't in the list of permitted next nodes" do
+    q = SmartAnswer::Question::Base.new(flow = nil, :question_name) {
+      permitted_next_nodes = [:allowed_next_node_1, :allowed_next_node_2]
+      next_node(permitted: permitted_next_nodes) { :not_allowed_next_node }
+    }
+    state = SmartAnswer::State.new(q.name)
+
+    expected_message = "Next node (not_allowed_next_node) not in list of permitted next nodes (allowed_next_node_1 and allowed_next_node_2)"
+    exception = assert_raises do
+      q.next_node_for(state, 'response')
+    end
+    assert_equal expected_message, exception.message
+  end
+
+  test 'permitted next nodes can be supplied to next_node' do
+    q = SmartAnswer::Question::Base.new(nil, :example) {
+      next_node(permitted: [:done]) do
+        :done
+      end
+    }
+    assert_equal [:done], q.permitted_next_nodes
+  end
+
   test "State is carried over on a state transition" do
     q = SmartAnswer::Question::Base.new(nil, :example) {
       next_node :done
@@ -34,8 +57,7 @@ class QuestionBaseTest < ActiveSupport::TestCase
 
   test "Can define next_node by giving a block, provided that next node is declared" do
     q = SmartAnswer::Question::Base.new(nil, :example) {
-      next_node { :done_done }
-      permitted_next_nodes(:done_done)
+      next_node(permitted: [:done_done]) { :done_done }
     }
     initial_state = SmartAnswer::State.new(q.name)
     new_state = q.transition(initial_state, :anything)
@@ -44,10 +66,10 @@ class QuestionBaseTest < ActiveSupport::TestCase
 
   test "next_node block can refer to state" do
     q = SmartAnswer::Question::Base.new(nil, :example) {
-      next_node do
+      permitted_next_nodes = [:was_red, :wasnt_red]
+      next_node(permitted: permitted_next_nodes) do
         colour == 'red' ? :was_red : :wasnt_red
       end
-      permitted_next_nodes(:was_red, :wasnt_red)
     }
     initial_state = SmartAnswer::State.new(q.name)
     initial_state.colour = 'red'
@@ -58,11 +80,10 @@ class QuestionBaseTest < ActiveSupport::TestCase
   test "next_node block is passed input" do
     input_was = nil
     q = SmartAnswer::Question::Base.new(nil, :example) {
-      next_node(:done) do |input|
+      next_node(permitted: [:done]) do |input|
         input_was = input
         :done
       end
-      permitted_next_nodes(:done)
     }
     initial_state = SmartAnswer::State.new(q.name)
     new_state = q.transition(initial_state, 'something')
@@ -193,8 +214,7 @@ class QuestionBaseTest < ActiveSupport::TestCase
   test "next_node block used as fallback" do
     q = SmartAnswer::Question::Base.new(nil, :example) {
       next_node_if(:skipped) { false }
-      next_node { :next }
-      permitted_next_nodes(:next)
+      next_node(permitted: [:next]) { :next }
     }
     initial_state = SmartAnswer::State.new(q.name)
     assert_equal :next, q.next_node_for(initial_state, :red)
@@ -203,7 +223,7 @@ class QuestionBaseTest < ActiveSupport::TestCase
   test "conditional next_node used if triggered ignoring fallback" do
     q = SmartAnswer::Question::Base.new(nil, :example) {
       next_node_if(:next) { true }
-      next_node { :ignored }
+      next_node(permitted: [:ignored]) { :ignored }
     }
     initial_state = SmartAnswer::State.new(q.name)
     assert_equal :next, q.next_node_for(initial_state, :red)