map net_income_known correctly for bulk upload

app/services/bulk_upload/lettings/row_parser.rb

@@ -478,7 +478,7 @@ private
 
     attributes["referral"] = field_78
 
-    attributes["net_income_known"] = field_51
+    attributes["net_income_known"] = net_income_known
     attributes["hb"] = field_48
     attributes["benefits"] = field_49
 
@@ -493,6 +493,19 @@ private
     attributes
   end
 
+  def net_income_known
+    case field_51
+    when 1
+      0
+    when 2
+      1
+    when 3
+      1
+    when 4
+      2
+    end
+  end
+
   def leftreg
     case field_114
     when 3

spec/services/bulk_upload/lettings/row_parser_spec.rb

@@ -448,5 +448,13 @@ RSpec.describe BulkUpload::Lettings::RowParser do
         expect(parser.log.relat8).to eq("X")
       end
     end
+
+    describe "#net_income_known" do
+      let(:attributes) { { bulk_upload:, field_51: "1" } }
+
+      it "sets value from correct mapping" do
+        expect(parser.log.net_income_known).to eq(0)
+      end
+    end
   end
 end