Fix a NullPointerException in DelegateJsonObject #3417 (#3418)

Author: brushmate

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

@@ -22,6 +22,7 @@
  *
  * @since 6.5
  * @author Tihomir Mateev
+ * @author Steffen Kreutz
  */
 public class DefaultJsonParser implements JsonParser {
 

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

@@ -15,6 +15,7 @@
  * Implementation of the {@link DelegateJsonObject} that delegates most of its functionality to the Jackson {@link ObjectNode}.
  *
  * @author Tihomir Mateev
+ * @author Steffen Kreutz
  */
 class DelegateJsonObject extends DelegateJsonValue implements JsonObject {
 
@@ -45,7 +46,7 @@ public JsonValue get(String key) {
     public JsonValue remove(String key) {
         JsonNode value = ((ObjectNode) node).remove(key);
 
-        return wrap(value);
+        return value == null ? null : wrap(value);
     }
 
     @Override

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

@@ -10,6 +10,7 @@
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import io.lettuce.core.internal.LettuceAssert;
 
 import java.nio.ByteBuffer;
 
@@ -110,6 +111,8 @@ public <T> T toObject(Class<T> type) {
     }
 
     static JsonValue wrap(JsonNode root) {
+        LettuceAssert.notNull(root, "Root must not be null");
+
         if (root.isObject()) {
             return new DelegateJsonObject(root);
         } else if (root.isArray()) {

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

@@ -37,13 +37,21 @@ void remove() {
         DefaultJsonParser parser = new DefaultJsonParser();
         DelegateJsonObject underTest = new DelegateJsonObject();
 
-        underTest.put("test", parser.createJsonValue("\"test\"")).put("test2", parser.createJsonValue("1")).remove("test");
+        underTest.put("test", parser.createJsonValue("\"test\"")).put("test2", parser.createJsonValue("1"));
 
+        assertThat(underTest.remove("test").asString()).isEqualTo("test");
         assertThat(underTest.size()).isEqualTo(1);
         assertThat(underTest.get("test")).isNull();
         assertThat(underTest.get("test2").asNumber()).isEqualTo(1);
     }
 
+    @Test
+    void removeNonExistingKey() {
+        DelegateJsonObject underTest = new DelegateJsonObject();
+
+        assertThat(underTest.remove("non existing key")).isNull();
+    }
+
     @Test
     void isAnythingElse() {
         DelegateJsonObject underTest = new DelegateJsonObject();