jsonArrpop fails with null return value (#3196)

src/main/java/io/lettuce/core/json/DefaultJsonParser.java

@@ -10,6 +10,7 @@
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.NullNode;
 
 import java.io.IOException;
 import java.nio.ByteBuffer;
@@ -61,6 +62,10 @@ public JsonValue fromObject(Object object) {
     }
 
     private JsonValue parse(String value) {
+        if (value == null) {
+            return DelegateJsonValue.wrap(NullNode.getInstance());
+        }
+
         ObjectMapper mapper = new ObjectMapper();
         try {
             JsonNode root = mapper.readTree(value);
@@ -72,6 +77,10 @@ private JsonValue parse(String value) {
     }
 
     private JsonValue parse(ByteBuffer byteBuffer) {
+        if (byteBuffer == null) {
+            return DelegateJsonValue.wrap(NullNode.getInstance());
+        }
+
         ObjectMapper mapper = new ObjectMapper();
         try {
             byte[] bytes = new byte[byteBuffer.remaining()];

src/main/java/io/lettuce/core/json/UnproccessedJsonValue.java

@@ -45,6 +45,11 @@ public UnproccessedJsonValue(ByteBuffer bytes, JsonParser theParser) {
 
     @Override
     public String toString() {
+
+        if (unprocessedData == null) {
+            return null;
+        }
+
         if (isDeserialized()) {
             return jsonValue.toString();
         }
@@ -161,7 +166,9 @@ private void lazilyDeserialize() {
             try {
                 if (!isDeserialized()) {
                     jsonValue = parser.createJsonValue(unprocessedData);
-                    unprocessedData.clear();
+                    if (unprocessedData != null) {
+                        unprocessedData.clear();
+                    }
                 }
             } finally {
                 lock.unlock();

src/main/java/io/lettuce/core/output/JsonValueListOutput.java

@@ -39,9 +39,13 @@ public void set(ByteBuffer bytes) {
             multi(1);
         }
 
-        ByteBuffer fetched = ByteBuffer.allocate(bytes.remaining());
-        fetched.put(bytes);
-        fetched.flip();
+        ByteBuffer fetched = null;
+        if (bytes != null) {
+            fetched = ByteBuffer.allocate(bytes.remaining());
+            fetched.put(bytes);
+            fetched.flip();
+        }
+
         output.add(parser.loadJsonValue(fetched));
     }
 

src/test/java/io/lettuce/core/json/RedisJsonIntegrationTests.java

@@ -157,6 +157,16 @@ void jsonArrpop(String path) {
                 "{\"id\":\"bike:3\",\"model\":\"Weywot\",\"description\":\"This bike gives kids aged six years and old");
     }
 
+    @Test
+    public void jsonArrpopEmptyArray() {
+        JsonValue value = redis.getJsonParser().createJsonValue("[\"one\"]");
+        redis.jsonSet("myKey", JsonPath.ROOT_PATH, value);
+        List<JsonValue> result = redis.jsonArrpop("myKey");
+        assertThat(result.toString()).isEqualTo("[\"one\"]");
+        result = redis.jsonArrpop("myKey", JsonPath.ROOT_PATH, 0);
+        assertThat(result.get(0).isNull()).isTrue();
+    }
+
     @ParameterizedTest(name = "With {0} as path")
     @ValueSource(strings = { BIKE_COLORS_V1, BIKE_COLORS_V2 })
     void jsonArrtrim(String path) {