From 8636e4f155c6b474ef6da54214c8549d0a8e35f5 Mon Sep 17 00:00:00 2001
From: jamesagnew <jamesagnew@gmail.com>
Date: Thu, 27 May 2021 07:30:09 -0400
Subject: [PATCH] Test fix

---
 .../main/java/ca/uhn/fhir/util/TerserUtil.java | 18 ++++++------------
 .../java/ca/uhn/fhir/util/TerserUtilTest.java  | 13 +++++++++++++
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/hapi-fhir-base/src/main/java/ca/uhn/fhir/util/TerserUtil.java b/hapi-fhir-base/src/main/java/ca/uhn/fhir/util/TerserUtil.java
index 4f447ab25c3..3b652f931f8 100644
--- a/hapi-fhir-base/src/main/java/ca/uhn/fhir/util/TerserUtil.java
+++ b/hapi-fhir-base/src/main/java/ca/uhn/fhir/util/TerserUtil.java
@@ -28,12 +28,10 @@ import ca.uhn.fhir.context.RuntimeResourceDefinition;
 import org.apache.commons.lang3.Validate;
 import org.apache.commons.lang3.tuple.Triple;
 import org.hl7.fhir.instance.model.api.IBase;
-import org.hl7.fhir.instance.model.api.IBaseEnumeration;
 import org.hl7.fhir.instance.model.api.IBaseResource;
 import org.hl7.fhir.instance.model.api.IPrimitiveType;
 import org.slf4j.Logger;
 
-import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.Arrays;
 import java.util.Collection;
@@ -47,18 +45,12 @@ import static org.slf4j.LoggerFactory.getLogger;
 
 public final class TerserUtil {
 
-	private static final Logger ourLog = getLogger(TerserUtil.class);
-
 	public static final String FIELD_NAME_IDENTIFIER = "identifier";
-
-	private static final String EQUALS_DEEP = "equalsDeep";
-
 	/**
 	 * Exclude for id, identifier and meta fields of a resource.
 	 */
 	public static final Collection<String> IDS_AND_META_EXCLUDES =
 		Collections.unmodifiableSet(Stream.of("id", "identifier", "meta").collect(Collectors.toSet()));
-
 	/**
 	 * Exclusion predicate for id, identifier, meta fields.
 	 */
@@ -68,7 +60,6 @@ public final class TerserUtil {
 			return !IDS_AND_META_EXCLUDES.contains(s);
 		}
 	};
-
 	/**
 	 * Exclusion predicate for id/identifier, meta and fields with empty values. This ensures that source / target resources,
 	 * empty source fields will not results in erasure of target fields.
@@ -84,7 +75,6 @@ public final class TerserUtil {
 			return !isSourceFieldEmpty;
 		}
 	};
-
 	/**
 	 * Exclusion predicate for keeping all fields.
 	 */
@@ -94,6 +84,8 @@ public final class TerserUtil {
 			return true;
 		}
 	};
+	private static final Logger ourLog = getLogger(TerserUtil.class);
+	private static final String EQUALS_DEEP = "equalsDeep";
 
 	private TerserUtil() {
 	}
@@ -448,9 +440,11 @@ public final class TerserUtil {
 	private static void replaceField(FhirTerser theTerser, IBaseResource theFrom, IBaseResource theTo, BaseRuntimeChildDefinition childDefinition) {
 		List<IBase> fromValues = childDefinition.getAccessor().getValues(theFrom);
 		List<IBase> toValues = childDefinition.getAccessor().getValues(theTo);
-		clear(toValues);
+		if (fromValues != toValues) {
+			clear(toValues);
 
-		mergeFields(theTerser, theTo, childDefinition, fromValues, toValues);
+			mergeFields(theTerser, theTo, childDefinition, fromValues, toValues);
+		}
 	}
 
 	/**
diff --git a/hapi-fhir-structures-r4/src/test/java/ca/uhn/fhir/util/TerserUtilTest.java b/hapi-fhir-structures-r4/src/test/java/ca/uhn/fhir/util/TerserUtilTest.java
index 9dafe34dc63..5611a3eca94 100644
--- a/hapi-fhir-structures-r4/src/test/java/ca/uhn/fhir/util/TerserUtilTest.java
+++ b/hapi-fhir-structures-r4/src/test/java/ca/uhn/fhir/util/TerserUtilTest.java
@@ -330,6 +330,19 @@ class TerserUtilTest {
 		assertEquals("Doe", p2.getName().get(0).getFamily());
 	}
 
+	@Test
+	public void testReplaceFields_SameValues() {
+		Patient p1 = new Patient();
+		p1.addName().setFamily("Doe");
+		Patient p2 = new Patient();
+		p2.setName(p1.getName());
+
+		TerserUtil.replaceField(ourFhirContext, "name", p1, p2);
+
+		assertEquals(1, p2.getName().size());
+		assertEquals("Doe", p2.getName().get(0).getFamily());
+	}
+
 	@Test
 	public void testReplaceFieldsByPredicate() {
 		Patient p1 = new Patient();