From 7a9fd5962dce7f277efa15fcc996606be0733bac Mon Sep 17 00:00:00 2001
From: Lyubomyr Shaydariv <lyubomyr-shaydariv@users.noreply.github.com>
Date: Mon, 18 Sep 2017 09:49:13 +0300
Subject: [PATCH] Fixed DefaultDateTypeAdapter nullability issue and JSON
 primitives contract (#1100)

* Fixed DefaultDateTypeAdapter nullability issue and JSON primitives contract

Regression in:

* b8f616c939c652b8540c95fa2b377b8c628ef3ff - Migrate DefaultDateTypeAdapter to streaming adapter (#1070)

Bug reports:

* https://github.com/google/gson/issues/1096 - 2.8.1 can't serialize and deserialize date null (2.8.0 works fine)
* https://github.com/google/gson/issues/1098 - Gson 2.8.1 DefaultDateTypeAdapter is not null safe.

* Fixed DefaultDateTypeAdapter nullability on write
---
 .../com/google/gson/DefaultDateTypeAdapter.java    |  9 +++++++--
 .../google/gson/DefaultDateTypeAdapterTest.java    | 14 ++++++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/gson/src/main/java/com/google/gson/DefaultDateTypeAdapter.java b/gson/src/main/java/com/google/gson/DefaultDateTypeAdapter.java
index 95eb42be..3ce97fe8 100644
--- a/gson/src/main/java/com/google/gson/DefaultDateTypeAdapter.java
+++ b/gson/src/main/java/com/google/gson/DefaultDateTypeAdapter.java
@@ -84,6 +84,10 @@ final class DefaultDateTypeAdapter extends TypeAdapter<Date> {
   // See issue 162
   @Override
   public void write(JsonWriter out, Date value) throws IOException {
+    if (value == null) {
+      out.nullValue();
+      return;
+    }
     synchronized (localFormat) {
       String dateFormatAsString = enUsFormat.format(value);
       out.value(dateFormatAsString);
@@ -92,8 +96,9 @@ final class DefaultDateTypeAdapter extends TypeAdapter<Date> {
 
   @Override
   public Date read(JsonReader in) throws IOException {
-    if (in.peek() != JsonToken.STRING) {
-      throw new JsonParseException("The date should be a string value");
+    if (in.peek() == JsonToken.NULL) {
+      in.nextNull();
+      return null;
     }
     Date date = deserializeToDate(in.nextString());
     if (dateType == Date.class) {
diff --git a/gson/src/test/java/com/google/gson/DefaultDateTypeAdapterTest.java b/gson/src/test/java/com/google/gson/DefaultDateTypeAdapterTest.java
index b3ee5a6f..3c787a66 100644
--- a/gson/src/test/java/com/google/gson/DefaultDateTypeAdapterTest.java
+++ b/gson/src/test/java/com/google/gson/DefaultDateTypeAdapterTest.java
@@ -161,6 +161,20 @@ public class DefaultDateTypeAdapterTest extends TestCase {
     } catch (IllegalArgumentException expected) { }
   }
 
+  public void testNullValue() throws Exception {
+    DefaultDateTypeAdapter adapter = new DefaultDateTypeAdapter(Date.class);
+    assertNull(adapter.fromJson("null"));
+    assertEquals("null", adapter.toJson(null));
+  }
+
+  public void testUnexpectedToken() throws Exception {
+    try {
+      DefaultDateTypeAdapter adapter = new DefaultDateTypeAdapter(Date.class);
+      adapter.fromJson("{}");
+      fail("Unexpected token should fail.");
+    } catch (IllegalStateException expected) { }
+  }
+
   private void assertFormatted(String formatted, DefaultDateTypeAdapter adapter) {
     assertEquals(toLiteral(formatted), adapter.toJson(new Date(0)));
   }