Update ObservationValueQuantityMapper to return an empty string and not generate a quantity if the value is not present in the valueQuantity

Remove duplicate unit test

Author: MartinWheelerMT

service/src/main/java/uk/nhs/adaptors/gp2gp/ehr/mapper/ObservationValueQuantityMapper.java

@@ -1,5 +1,6 @@
 package uk.nhs.adaptors.gp2gp.ehr.mapper;
 
+import org.apache.commons.lang3.StringUtils;
 import org.hl7.fhir.dstu3.model.BooleanType;
 import org.hl7.fhir.dstu3.model.Extension;
 import org.hl7.fhir.dstu3.model.Quantity;
@@ -71,6 +72,10 @@ private ObservationValueQuantityMapper() {
     }
 
     public static String processQuantity(Quantity valueQuantity) {
+        if (!valueQuantity.hasValue()) {
+            return StringUtils.EMPTY;
+        }
+
         var stringBuilder = new StringBuilder();
 
         if (isUncertaintyCodePresent(valueQuantity)) {

service/src/test/java/uk/nhs/adaptors/gp2gp/ehr/mapper/ObservationValueQuantityMapperTest.java

@@ -114,6 +114,16 @@ public void When_MappingQuantityWithUncertaintyExtension_Expect_XmlContainsUncer
         assertThat(mappedQuantity).isEqualTo(expectedXml);
     }
 
+    @Test
+    public void When_MappingQuantityWithNullValue_ExpectedEmptyString() {
+        var quantity = (Quantity) new Quantity()
+            .setSystem(UOM_SYSTEM)
+            .setCode(CODE_CEL);
+        var mappedQuantity = ObservationValueQuantityMapper.processQuantity(quantity);
+
+        assertThat(mappedQuantity).isEmpty();
+    }
+
     @Test
     public void When_MappingQuantityWithUOMSystemAndCode_Expect_PQXmlWithValueAndQuantitySetAndNoTranslation() {
         var quantity = new Quantity()
@@ -239,19 +249,6 @@ public void When_MappingQuantityWithAnyOrNoSystemWithoutUnitOrCode_Expect_PQXmlW
         assertThat(mappedQuantity).isEqualTo(expectedXml);
     }
 
-    @Test
-    public void When_MappingQuantityWithoutSystemOrUnitOrCode_Expect_PQXmlWithValueSetAndUnitSetToOne() {
-        var quantity = new Quantity()
-            .setValue(VALUE_37_1);
-
-        var expectedXml = """
-            <value xsi:type="PQ" value="37.1" unit="1" />""";
-
-        var mappedQuantity = ObservationValueQuantityMapper.processQuantity(quantity);
-
-        assertThat(mappedQuantity).isEqualTo(expectedXml);
-    }
-
     @Test
     public void When_MappingQuantityWithUncertaintyAndComparatorExtension_Expect_XmlContainsUncertaintyCode() {
         var quantity = (Quantity) new Quantity()