Block invalid policy combinations

The business rules state that certain policy combinations aren't
permitted, eg if a claimant has made an ECP claim they can't make a
second claim for FE in the same academic year. In such an invalid claim
scenario the requirement is to disable the approve button so admins
can't approve the claim.

app/models/claim.rb

@@ -284,7 +284,12 @@ def approvable?
       (!decision_made? || awaiting_qa?) &&
       !payment_prevented_by_other_claims? &&
       attributes_flagged_by_risk_indicator.none? &&
-      policy.approvable?(self)
+      policy.approvable?(self) &&
+      !precluded_by_previous_claim?
+  end
+
+  def approved?
+    decision_made? && latest_decision.approved?
   end
 
   def rejectable?
@@ -296,7 +301,7 @@ def holdable?
   end
 
   def flaggable_for_qa?
-    decision_made? && latest_decision.approved? && below_min_qa_threshold? && !awaiting_qa? && !qa_completed?
+    approved? && below_min_qa_threshold? && !awaiting_qa? && !qa_completed?
   end
 
   # This method's intention is to help make a decision on whether a claim should
@@ -570,4 +575,18 @@ def submittable_mobile_details?
   def submittable_email_details?
     email_address.present? && email_verified == true
   end
+
+  def claims_from_same_claimant
+    @claims_from_same_claimant ||= MatchingAttributeFinder.new(self).matching_claims
+  end
+
+  def precluded_by_previous_claim?
+    approved_claims = claims_from_same_claimant.select(&:approved?)
+
+    other_claimed_policies = approved_claims.map(&:policy)
+
+    policies_claimed = (other_claimed_policies + [policy]).uniq
+
+    Policies.prohibited_policy_combination?(policies_claimed)
+  end
 end

app/models/policies.rb

@@ -41,4 +41,22 @@ def self.constantize(policy)
   def self.with_attribute(attr)
     POLICIES.select { |policy| policy::Eligibility.has_attribute?(attr) }
   end
+
+  # Claimants can't claim for these policy combinations in the same academic
+  # year
+  INVALID_POLICY_COMBINATIONS = [
+    [EarlyCareerPayments, FurtherEducationPayments],
+    [EarlyCareerPayments, LevellingUpPremiumPayments],
+    [FurtherEducationPayments, LevellingUpPremiumPayments],
+    [FurtherEducationPayments, StudentLoans],
+    [FurtherEducationPayments, InternationalRelocationPayments],
+    [EarlyYearsPayments, EarlyCareerPayments],
+    [EarlyCareerPayments, LevellingUpPremiumPayments]
+  ]
+
+  def self.prohibited_policy_combination?(policies)
+    policies.combination(2).any? do |policy1, policy2|
+      INVALID_POLICY_COMBINATIONS.include?([policy1, policy2].sort_by(&:to_s))
+    end
+  end
 end

spec/features/admin/claim_with_unpermitted_policy_combo_spec.rb

@@ -0,0 +1,77 @@
+require "rails_helper"
+
+RSpec.describe "Claim with unpermitted policy combo" do
+  context "when one of the claims has been approved" do
+    it "doesn't allow the admin to approve the other claim" do
+      create(
+        :claim,
+        :approved,
+        :current_academic_year,
+        policy: Policies::InternationalRelocationPayments,
+        email_address: "[email protected]"
+      )
+
+      duplicate_claim = create(
+        :claim,
+        :submitted,
+        :current_academic_year,
+        policy: Policies::FurtherEducationPayments,
+        email_address: "[email protected]"
+      )
+
+      sign_in_as_service_operator
+
+      visit new_admin_claim_decision_path(duplicate_claim)
+
+      approve_option = find("input[type=radio][value=approved]")
+
+      expect(approve_option).to be_disabled
+    end
+  end
+
+  context "when neither of the claims have been approved" do
+    it "allows the admin to approve one of the claims" do
+      irp_claim = create(
+        :claim,
+        :submitted,
+        :current_academic_year,
+        policy: Policies::InternationalRelocationPayments,
+        email_address: "[email protected]"
+      )
+
+      fe_claim = create(
+        :claim,
+        :submitted,
+        :current_academic_year,
+        policy: Policies::FurtherEducationPayments,
+        email_address: "[email protected]"
+      )
+
+      sign_in_as_service_operator
+
+      visit new_admin_claim_decision_path(irp_claim)
+
+      approve_option = find("input[type=radio][value=approved]")
+
+      expect(approve_option).not_to be_disabled
+
+      visit new_admin_claim_decision_path(fe_claim)
+
+      approve_option = find("input[type=radio][value=approved]")
+
+      expect(approve_option).not_to be_disabled
+
+      choose "Approve"
+
+      fill_in "Decision notes", with: "LGTM"
+
+      click_on "Confirm decision"
+
+      visit new_admin_claim_decision_path(irp_claim)
+
+      approve_option = find("input[type=radio][value=approved]")
+
+      expect(approve_option).to be_disabled
+    end
+  end
+end

spec/models/claim_spec.rb

@@ -392,6 +392,54 @@
         expect(subject).not_to be_approvable
       end
     end
+
+    context "when the claimant has claimed for a policy that precludes them from this policy" do
+      subject do
+        create(
+          :claim,
+          :submitted,
+          :current_academic_year,
+          policy: Policies::FurtherEducationPayments,
+          email_address: "[email protected]"
+        )
+      end
+
+      context "when the other claim has been approved" do
+        it "is not approvable" do
+          create(
+            :claim,
+            :approved,
+            :current_academic_year,
+            policy: Policies::EarlyCareerPayments,
+            email_address: "[email protected]"
+          )
+
+          expect(subject).not_to be_approvable
+        end
+      end
+
+      context "when the other claim has not been approved" do
+        it "is approvable" do
+          create(
+            :claim,
+            :submitted,
+            :current_academic_year,
+            policy: Policies::EarlyCareerPayments,
+            email_address: "[email protected]"
+          )
+
+          create(
+            :claim,
+            :rejected,
+            :current_academic_year,
+            policy: Policies::EarlyCareerPayments,
+            email_address: "[email protected]"
+          )
+
+          expect(subject).to be_approvable
+        end
+      end
+    end
   end
 
   describe "#rejectable?" do