Only blank tenancy lenght when it is invalid for tenancy type

app/services/imports/lettings_logs_import_service.rb

@@ -318,7 +318,7 @@ module Imports
         %i[chcharge out_of_range] => %w[chcharge],
         %i[referral internal_transfer_non_social_housing] => %w[referral],
         %i[referral internal_transfer_fixed_or_lifetime] => %w[referral],
-        %i[tenancylength tenancylength_invalid] => %w[tenancylength tenancy],
+        %i[tenancylength tenancylength_invalid] => %w[tenancylength],
         %i[prevten over_25_foster_care] => %w[prevten age1],
         %i[prevten non_temp_accommodation] => %w[prevten rsnvac],
         %i[joint not_joint_tenancy] => %w[joint],

spec/services/imports/lettings_logs_import_service_spec.rb

@@ -325,7 +325,7 @@ RSpec.describe Imports::LettingsLogsImportService do
             .not_to raise_error
         end
 
-        it "clears out the invalid answers" do
+        it "clears out the invalid tenancy lenght" do
           allow(logger).to receive(:warn)
 
           lettings_log_service.send(:create_log, lettings_log_xml)
@@ -333,7 +333,7 @@ RSpec.describe Imports::LettingsLogsImportService do
 
           expect(lettings_log).not_to be_nil
           expect(lettings_log.tenancylength).to be_nil
-          expect(lettings_log.tenancy).to be_nil
+          expect(lettings_log.tenancy).to eq(4)
         end
       end