Fix MMR dose sequence validation error message

Show programme-specific dose sequence guidance when the uploaded
value is not a valid integer, so MMR now correctly says the maximum
dose sequence is 2 and gives examples of 1 or 2 instead of the
generic 1, 2 or 3 message.

Jira-Issue: MAV-2312

Author: jhenderson

app/models/immunisation_import_row.rb

@@ -843,12 +843,18 @@ def validate_dose_sequence
 
     field = dose_sequence || combined_vaccination_and_dose_sequence
 
+    dose_sequence_examples =
+      (1..maximum_dose_sequence).to_a.to_sentence(
+        last_word_connector: " or ",
+        two_words_connector: " or "
+      )
+
     if dose_sequence.present? ||
          parsed_vaccination_description_string&.dig(:dose_sequence).present?
       if dose_sequence_value.nil?
         errors.add(
           field.header,
-          "Enter a dose sequence number, for example, 1, 2 or 3."
+          "Enter a dose sequence number, for example, #{dose_sequence_examples}."
         )
       elsif maximum_dose_sequence
         if dose_sequence_value < 1
@@ -873,7 +879,7 @@ def validate_dose_sequence
       else
         errors.add(
           field.header,
-          "Enter a dose sequence number, for example, 1, 2 or 3. The dose sequence number cannot be greater than 6."
+          "Enter a dose sequence number, for example, #{dose_sequence_examples}."
         )
       end
     end

spec/models/immunisation_import_row_spec.rb

@@ -575,6 +575,18 @@
         end
       end
 
+      context "with an invalid dose sequence for MMR" do
+        let(:programmes) { [Programme.mmr] }
+        let(:data) { { "PROGRAMME" => "MMR", "DOSE_SEQUENCE" => "unknown" } }
+
+        it "has the correct error message" do
+          immunisation_import_row.valid?
+          expect(immunisation_import_row.errors["DOSE_SEQUENCE"]).to include(
+            "Enter a dose sequence number, for example, 1 or 2."
+          )
+        end
+      end
+
       context "with an invalid dose sequence" do
         let(:programmes) { [Programme.hpv] }