added PostcodeService to extract behavior

app/controllers/locations_controller.rb

@@ -70,7 +70,7 @@ private
 
   def location_params
     required_params = params.require(:location).permit(:postcode, :name, :total_units, :type_of_unit, :wheelchair_adaptation, :add_another_location).merge(scheme_id: @scheme.id)
-    required_params[:postcode] = required_params[:postcode].delete(" ").upcase.encode("ASCII", "UTF-8", invalid: :replace, undef: :replace, replace: "") if required_params[:postcode]
+    required_params[:postcode] = PostcodeService.clean(required_params[:postcode].delete(" ").upcase) if required_params[:postcode]
     required_params
   end
 end

app/models/case_log.rb

@@ -590,7 +590,7 @@ private
     postcode_lookup = nil
     begin
       # URI encoding only supports ASCII characters
-      ascii_postcode = postcode.encode("ASCII", "UTF-8", invalid: :replace, undef: :replace, replace: "")
+      ascii_postcode = PostcodeService.clean(postcode)
       Timeout.timeout(5) { postcode_lookup = PIO.lookup(ascii_postcode) }
     rescue Timeout::Error
       Rails.logger.warn("Postcodes.io lookup timed out")

app/services/postcode_service.rb

@@ -0,0 +1,6 @@
+class PostcodeService
+
+  def self.clean(postcode)
+    postcode.encode("ASCII", "UTF-8", invalid: :replace, undef: :replace, replace: "")
+  end
+end

spec/services/postcode_service_spec.rb

@@ -0,0 +1,9 @@
+require "rails_helper"
+
+describe PostcodeService do
+  let(:postcode) { "SR81LS\u00A0" }
+
+  it "triggers a validation error" do
+    expect(described_class.clean(postcode)).to eq "SR81LS"
+  end
+end