From 675bb3506a8d08f8e4d2a340b084019c40492a7c Mon Sep 17 00:00:00 2001
From: Drew Michel <dmichel@spotify.com>
Date: Sun, 25 Nov 2018 09:50:20 -0500
Subject: [PATCH] [json] regression test for null value
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

A JSON null value is being translated to a “null” string.

Was supposed to be fixed in https://github.com/FasterXML/jackson-databind/issues/1842 but it doesn’t appear to be.
---
 modules/json/pom.xml                          |  8 +++++
 .../ffwd/json/JsonObjectMapperDecoder.java    |  2 +-
 .../json/JsonObjectMapperDecoderTest.java     | 29 +++++++++++++++++++
 3 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 modules/json/src/test/java/com/spotify/ffwd/json/JsonObjectMapperDecoderTest.java

diff --git a/modules/json/pom.xml b/modules/json/pom.xml
index 9f268b29..435ed97a 100644
--- a/modules/json/pom.xml
+++ b/modules/json/pom.xml
@@ -23,5 +23,13 @@
       <groupId>com.spotify.ffwd</groupId>
       <artifactId>ffwd-api</artifactId>
     </dependency>
+
+    <!-- testing -->
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
+
 </project>
diff --git a/modules/json/src/main/java/com/spotify/ffwd/json/JsonObjectMapperDecoder.java b/modules/json/src/main/java/com/spotify/ffwd/json/JsonObjectMapperDecoder.java
index 6c78a656..547c9985 100644
--- a/modules/json/src/main/java/com/spotify/ffwd/json/JsonObjectMapperDecoder.java
+++ b/modules/json/src/main/java/com/spotify/ffwd/json/JsonObjectMapperDecoder.java
@@ -169,7 +169,7 @@ private double decodeDouble(JsonNode tree, String name) {
         return n.asDouble();
     }
 
-    private String decodeString(JsonNode tree, String name) {
+    String decodeString(JsonNode tree, String name) {
         final JsonNode n = tree.get(name);
 
         if (n == null) {
diff --git a/modules/json/src/test/java/com/spotify/ffwd/json/JsonObjectMapperDecoderTest.java b/modules/json/src/test/java/com/spotify/ffwd/json/JsonObjectMapperDecoderTest.java
new file mode 100644
index 00000000..a3d52938
--- /dev/null
+++ b/modules/json/src/test/java/com/spotify/ffwd/json/JsonObjectMapperDecoderTest.java
@@ -0,0 +1,29 @@
+package com.spotify.ffwd.json;
+
+import static junit.framework.TestCase.assertNull;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import java.io.IOException;
+import org.junit.Before;
+import org.junit.Test;
+
+public class JsonObjectMapperDecoderTest {
+  private final ObjectMapper mapper = new ObjectMapper();
+
+  private JsonObjectMapperDecoder j;
+
+  @Before
+  public void setup() {
+   j = new JsonObjectMapperDecoder();
+  }
+
+  @Test
+  public void nullKey() throws IOException {
+    final JsonNode json = mapper.readTree("{\"key\": null}");
+    final String key = j.decodeString(json, "key");
+
+    assertNull(key);
+  }
+
+}