From a7c9e9aca586370bf7b2c49e3c2e14dec61e8a02 Mon Sep 17 00:00:00 2001
From: Rob Bygrave <robin.bygrave@gmail.com>
Date: Mon, 16 Dec 2024 17:44:57 +1300
Subject: [PATCH] [json-core] Fix reading NULL value in a Map or List (#318)

---
 .../org/example/other/ObjectAdapterTest.java  | 18 +++++++++++++
 .../avaje/json/core/BasicObjectAdapter.java   |  1 +
 .../avaje/json/simple/SimpleMapperTest.java   | 26 +++++++++++++++++++
 3 files changed, 45 insertions(+)

diff --git a/blackbox-test/src/test/java/org/example/other/ObjectAdapterTest.java b/blackbox-test/src/test/java/org/example/other/ObjectAdapterTest.java
index edbd674c..e373bb3c 100644
--- a/blackbox-test/src/test/java/org/example/other/ObjectAdapterTest.java
+++ b/blackbox-test/src/test/java/org/example/other/ObjectAdapterTest.java
@@ -30,6 +30,24 @@ void nullJson() {
     assertThat(asJson).isEqualTo("");
   }
 
+  @Test
+  void nullInMap() {
+    Object val = objectType.fromJson("{\"a\":1,\"b\":null,\"c\":3}");
+    assertThat(val).isInstanceOf(Map.class);
+
+    String asJson = objectType.toJson(null);
+    assertThat(asJson).isEqualTo("");
+  }
+
+  @Test
+  void nullInList() {
+    Object val = objectType.fromJson("[1,null,3]");
+    assertThat(val).isInstanceOf(List.class);
+
+    String asJson = objectType.toJson(val);
+    assertThat(asJson).isEqualTo("[1,3]");
+  }
+
   @Test
   void booleanTrue() {
     String asJson = objectType.toJson(true);
diff --git a/json-core/src/main/java/io/avaje/json/core/BasicObjectAdapter.java b/json-core/src/main/java/io/avaje/json/core/BasicObjectAdapter.java
index dfb5f8cb..9e494da1 100644
--- a/json-core/src/main/java/io/avaje/json/core/BasicObjectAdapter.java
+++ b/json-core/src/main/java/io/avaje/json/core/BasicObjectAdapter.java
@@ -60,6 +60,7 @@ public Object fromJson(JsonReader reader) {
       case BOOLEAN:
         return booleanAdapter.fromJson(reader);
       case NULL:
+        reader.isNullValue();
         return null;
       default:
         throw new IllegalStateException("Expected a value but was " + reader.currentToken() + " at path " + reader.location());
diff --git a/json-core/src/test/java/io/avaje/json/simple/SimpleMapperTest.java b/json-core/src/test/java/io/avaje/json/simple/SimpleMapperTest.java
index 9666b2a3..48c262d1 100644
--- a/json-core/src/test/java/io/avaje/json/simple/SimpleMapperTest.java
+++ b/json-core/src/test/java/io/avaje/json/simple/SimpleMapperTest.java
@@ -32,6 +32,32 @@ void mapToJsonFromJson() {
     assertThat(mapFromJson2).isEqualTo(mapFromJson);
   }
 
+  @Test
+  void nullDirectly() {
+   var mapFromJson = simpleMapper.fromJson("null");
+    assertThat(mapFromJson).isNull();
+  }
+
+  @Test
+  void mapWithNull() {
+    Map<String, Object> mapFromJson = simpleMapper.fromJsonObject("{\"one\":1,\"two\":null,\"three\":3}");
+
+    assertThat(mapFromJson).containsKeys("one", "two", "three");
+    assertThat(mapFromJson.toString()).isEqualTo("{one=1, two=null, three=3}");
+
+    assertThat(simpleMapper.toJson(mapFromJson)).isEqualTo("{\"one\":1,\"three\":3}");
+  }
+
+  @Test
+  void listWithNull() {
+    List<Object> listFromJson = simpleMapper.fromJsonArray("[1,null,3]");
+
+    assertThat(listFromJson).hasSize(3);
+    assertThat(listFromJson.get(1)).isNull();
+
+    assertThat(simpleMapper.toJson(listFromJson)).isEqualTo("[1,3]");
+  }
+
   @Test
   void arrayToJsonFromJson() {