normalise NI number before saving in answers

app/forms/personal_details_form.rb

@@ -56,7 +56,7 @@ def save
       middle_name:,
       surname:,
       date_of_birth:,
-      national_insurance_number:
+      national_insurance_number: normalised_ni_number
     )
 
     reset_dependent_answers_attributes

spec/features/further_education_payments/happy_path_spec.rb

@@ -126,7 +126,7 @@
     fill_in "Day", with: "28"
     fill_in "Month", with: "2"
     fill_in "Year", with: "1988"
-    fill_in "National Insurance number", with: "PX321499A"
+    fill_in "National Insurance number", with: "PX321499A " # deliberate trailing space
     click_on "Continue"
 
     expect(page).to have_content("What is your home address?")

spec/forms/personal_details_form_spec.rb

@@ -342,10 +342,10 @@
     end
 
     describe "#save" do
-      context "with valid params" do
-        let(:logged_in_with_tid) { nil }
-        let(:teacher_id_user_info) { {} }
+      let(:logged_in_with_tid) { nil }
+      let(:teacher_id_user_info) { {} }
 
+      context "with valid params" do
         let(:params) do
           {
             first_name: "Dr",
@@ -379,6 +379,25 @@
           expect(answers.student_loan_plan).to be nil
         end
       end
+
+      context "with a national insurance number with spaces" do
+        let(:params) do
+          {
+            first_name: "Dr",
+            middle_name: "Bob",
+            surname: "Loblaw",
+            day: 1,
+            month: 1,
+            year: 1990,
+            national_insurance_number: "QQ 123456 C "
+          }
+        end
+
+        it "strips spaces" do
+          form.save
+          expect(journey_session.answers.national_insurance_number).to eq "QQ123456C"
+        end
+      end
     end
   end