Make below_min_qa_threshold an instance method

This method is only used in one place, in an instance method on Claim,
so it doesn't need to be a class method. By moving this method to be an
instance method it will be easier to overwrite the MIN_QA_THRESHOLD on a
per policy basis.

app/models/claim.rb

@@ -181,31 +181,6 @@ class Claim < ApplicationRecord
   scope :awaiting_qa, -> { approved.qa_required.where(qa_completed_at: nil) }
   scope :qa_required, -> { where(qa_required: true) }
 
-  # This method's intention is to help make a decision on whether a claim should
-  # be flagged for QA or not. These criteria need to be met for each academic year:
-  #
-  # 1. the first claim to be approved should always be flagged for QA
-  # 2. subsequently approved claims should be flagged for QA, 1 in 100/MIN_QA_THRESHOLD.
-  #
-  # This method should be used every time a new approval decision is being made;
-  # when used retrospectively, i.e. when several claims have been approved,
-  # the method returns:
-  #
-  # 1. `true` if none of then claims have been flagged for QA
-  # 2. `true` if some claims have been flagged for QA using a lower MIN_QA_THRESHOLD
-  # 3. `false` if some claims have been flagged for QA using a higher MIN_QA_THRESHOLD
-  #
-  # Newly approved claims should not be flagged for QA for as long as the method
-  # returns `false`; they should be flagged for QA otherwise.
-  def self.below_min_qa_threshold?
-    return false if MIN_QA_THRESHOLD.zero?
-
-    claims_approved_so_far = current_academic_year.approved.count
-    return true if claims_approved_so_far.zero?
-
-    (current_academic_year.approved.qa_required.count.to_f / claims_approved_so_far) * 100 <= MIN_QA_THRESHOLD
-  end
-
   def hold!(reason:, user:)
     if holdable? && !held?
       self.class.transaction do
@@ -245,7 +220,32 @@ def holdable?
   end
 
   def flaggable_for_qa?
-    decision_made? && latest_decision.approved? && Claim.below_min_qa_threshold? && !awaiting_qa? && !qa_completed?
+    decision_made? && latest_decision.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
+  # be flagged for QA or not. These criteria need to be met for each academic year:
+  #
+  # 1. the first claim to be approved should always be flagged for QA
+  # 2. subsequently approved claims should be flagged for QA, 1 in 100/MIN_QA_THRESHOLD.
+  #
+  # This method should be used every time a new approval decision is being made;
+  # when used retrospectively, i.e. when several claims have been approved,
+  # the method returns:
+  #
+  # 1. `true` if none of then claims have been flagged for QA
+  # 2. `true` if some claims have been flagged for QA using a lower MIN_QA_THRESHOLD
+  # 3. `false` if some claims have been flagged for QA using a higher MIN_QA_THRESHOLD
+  #
+  # Newly approved claims should not be flagged for QA for as long as the method
+  # returns `false`; they should be flagged for QA otherwise.
+  def below_min_qa_threshold?
+    return false if MIN_QA_THRESHOLD.zero?
+
+    claims_approved_so_far = Claim.current_academic_year.approved.count
+    return true if claims_approved_so_far.zero?
+
+    (Claim.current_academic_year.approved.qa_required.count.to_f / claims_approved_so_far) * 100 <= MIN_QA_THRESHOLD
   end
 
   def qa_completed?

spec/models/claim_spec.rb

@@ -371,15 +371,15 @@
 
       context "when above the min QA threshold" do
         before do
-          allow(Claim).to receive(:below_min_qa_threshold?).and_return(false)
+          stub_const("Claim::MIN_QA_THRESHOLD", 0)
         end
 
         it { is_expected.to eq(false) }
       end
 
       context "when below the min QA threshold" do
         before do
-          allow(Claim).to receive(:below_min_qa_threshold?).and_return(true)
+          stub_const("Claim::MIN_QA_THRESHOLD", 100)
         end
 
         it { is_expected.to eq(true) }
@@ -597,8 +597,8 @@
     end
   end
 
-  describe ".below_min_qa_threshold?" do
-    subject { described_class.below_min_qa_threshold? }
+  describe "#below_min_qa_threshold?" do
+    subject { described_class.new.below_min_qa_threshold? }
 
     context "when the MIN_QA_THRESHOLD is set to zero" do
       before do