Unset number_of_terms when induction period ongoing

There should never be a number_of_terms present on an ongoing induction
period.

lib/appropriate_bodies/importers/induction_period_importer.rb

@@ -31,15 +31,19 @@ def to_h
 
       # used for comparisons in tests
       def to_hash
-        { appropriate_body_id:, started_on:, finished_on:, induction_programme: convert_induction_programme, number_of_terms: }
+        { appropriate_body_id:, started_on:, finished_on:, induction_programme: convert_induction_programme, number_of_terms: fixed_number_of_terms}
       end
 
       def to_record
-        { appropriate_body_id:, started_on:, finished_on:, induction_programme: convert_induction_programme, number_of_terms:, teacher_id: }
+        { **to_hash, teacher_id: }
       end
 
     private
 
+      def fixed_number_of_terms
+        (finished_on.present?) ? number_of_terms : nil
+      end
+
       def convert_induction_programme
         {
           "Full Induction Programme" => "fip",

spec/lib/appropriate_bodies/importers/induction_period_importer_spec.rb

@@ -43,6 +43,23 @@
     end
   end
 
+  describe 'number of terms' do
+    context 'when number_of_terms is present and finished_on is blank' do
+      let(:sample_csv_data) do
+        <<~CSV
+          appropriate_body_id,started_on,finished_on,induction_programme_choice,number_of_terms,trn
+          025e61e7-ec32-eb11-a813-000d3a228dfc,01/01/2012 00:00:00,,,3,2600071
+        CSV
+      end
+
+      it 'sets the number_of_terms to nil' do
+        row_data = subject.periods_as_hashes_by_trn['2600071'].first
+        expect(row_data.fetch(:started_on)).to eql(Date.new(2012, 1, 1))
+        expect(row_data.fetch(:number_of_terms)).to be_nil
+      end
+    end
+  end
+
   describe 'rebuilding periods' do
     context 'when an ECT has no open induction periods' do
       let(:sample_csv_data) do