diff --git a/org.hl7.fhir.r4/src/test/java/org/hl7/fhir/r4/terminologies/ConceptMapEngineTest.java b/org.hl7.fhir.r4/src/test/java/org/hl7/fhir/r4/terminologies/ConceptMapEngineTest.java
index 3c4a006a2..6e2992bc2 100644
--- a/org.hl7.fhir.r4/src/test/java/org/hl7/fhir/r4/terminologies/ConceptMapEngineTest.java
+++ b/org.hl7.fhir.r4/src/test/java/org/hl7/fhir/r4/terminologies/ConceptMapEngineTest.java
@@ -1,17 +1,23 @@
 package org.hl7.fhir.r4.terminologies;
 
+import org.hl7.fhir.exceptions.FHIRException;
 import org.hl7.fhir.r4.context.SimpleWorkerContext;
 import org.hl7.fhir.r4.model.Coding;
 import org.hl7.fhir.r4.model.ConceptMap;
 import org.hl7.fhir.r4.model.Enumerations;
+import javax.annotation.Nonnull;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 
-import javax.annotation.Nonnull;
 import java.io.IOException;
+import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
 
 class ConceptMapEngineTest {
 
@@ -20,9 +26,12 @@ class ConceptMapEngineTest {
   public static final String TARGET_CODE_STRING = "vital-signs";
 
   @Test
-  @DisplayName("Coding is converted according to ConceptMap")
-  void translate() throws IOException {
-    ConceptMapEngine conceptMapEngine = getConceptMapEngine();
+  @DisplayName("Coding is translated according to ConceptMap")
+  void codingTranslate() throws IOException {
+
+    final ConceptMap.SourceElementComponent sourceElementComponent = getSourceElementComponent();
+
+    final ConceptMapEngine conceptMapEngine = getConceptMapEngine(Arrays.asList(sourceElementComponent));
     Coding coding = new Coding(null, SOURCE_CODE_STRING, "Body Weight");
 
     Coding actual = conceptMapEngine.translate(coding, CONCEPT_MAP_URL);
@@ -30,18 +39,34 @@ class ConceptMapEngineTest {
     assertEquals(TARGET_CODE_STRING, actual.getCode());
   }
 
-  @Nonnull
-  private ConceptMapEngine getConceptMapEngine() throws IOException {
-    ConceptMap conceptMap = getConceptMap();
+  @Test
+  @DisplayName("Coding fails to translate due to multiple candidate matches in ConceptMap")
+  void codingTranslateFailsForMultipleCandidateMatches() throws IOException {
 
-    SimpleWorkerContext simpleWorkerContext = new SimpleWorkerContext();
-    simpleWorkerContext.cacheResource(conceptMap);
+    final ConceptMap.SourceElementComponent sourceElementComponent = getSourceElementComponent();
+
+    final ConceptMapEngine conceptMapEngine = getConceptMapEngine(Arrays.asList(sourceElementComponent,
+                                                sourceElementComponent
+                                              ));
+    Coding coding = new Coding(null, SOURCE_CODE_STRING, "Body Weight");
+
+    assertThrows(FHIRException.class, () -> {
+      conceptMapEngine.translate(coding, CONCEPT_MAP_URL);
+    });
+  }
+
+  @Nonnull
+  private ConceptMapEngine getConceptMapEngine(Collection<ConceptMap.SourceElementComponent> elements) throws IOException {
+    ConceptMap conceptMap = getConceptMap(elements);
+
+    SimpleWorkerContext simpleWorkerContext = mock(SimpleWorkerContext.class);
+    when(simpleWorkerContext.fetchResource(ConceptMap.class, CONCEPT_MAP_URL)).thenReturn(conceptMap);
 
     return new ConceptMapEngine(simpleWorkerContext);
   }
 
   @Nonnull
-  private ConceptMap getConceptMap() {
+  private ConceptMap.SourceElementComponent getSourceElementComponent() {
     ConceptMap.TargetElementComponent targetElementComponent = new ConceptMap.TargetElementComponent();
     targetElementComponent.setCode(TARGET_CODE_STRING);
     targetElementComponent.setEquivalence(Enumerations.ConceptMapEquivalence.EQUIVALENT);
@@ -50,9 +75,16 @@ class ConceptMapEngineTest {
     sourceElementComponent.setCode(SOURCE_CODE_STRING);
     sourceElementComponent.setTarget(Collections.singletonList(targetElementComponent));
 
-    ConceptMap.ConceptMapGroupComponent conceptMapGroupComponent = new ConceptMap.ConceptMapGroupComponent();
-    conceptMapGroupComponent.addElement(sourceElementComponent);
+    return sourceElementComponent;
+  }
 
+  @Nonnull
+  private ConceptMap getConceptMap(Collection<ConceptMap.SourceElementComponent> elements) {
+
+    ConceptMap.ConceptMapGroupComponent conceptMapGroupComponent = new ConceptMap.ConceptMapGroupComponent();
+    for (ConceptMap.SourceElementComponent element : elements) {
+      conceptMapGroupComponent.addElement(element);
+    }
     return new ConceptMap()
       .addGroup(conceptMapGroupComponent)
       .setUrl(CONCEPT_MAP_URL);