From 7b9ed3c580b256d251ba8ecf0ef791b1c63e117c Mon Sep 17 00:00:00 2001
From: Jenn Magder <magder@google.com>
Date: Mon, 29 Jan 2024 18:15:00 -0800
Subject: [PATCH] Log FlutterJSONMessageCodec decode errors before asserting

---
 .../common/framework/Source/FlutterCodecs.mm      |  5 +++--
 .../framework/Source/flutter_codecs_unittest.mm   | 15 +++++++++++++++
 testing/run_all_unittests.cc                      |  1 +
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/shell/platform/darwin/common/framework/Source/FlutterCodecs.mm b/shell/platform/darwin/common/framework/Source/FlutterCodecs.mm
index 57ef1eb752a4a..a8653477e2c03 100644
--- a/shell/platform/darwin/common/framework/Source/FlutterCodecs.mm
+++ b/shell/platform/darwin/common/framework/Source/FlutterCodecs.mm
@@ -89,6 +89,7 @@ - (id)decode:(NSData*)message {
   }
   BOOL isSimpleValue = NO;
   id decoded = nil;
+  NSError* error;
   if (0 < message.length) {
     UInt8 first;
     [message getBytes:&first length:1];
@@ -105,9 +106,9 @@ - (id)decode:(NSData*)message {
       [expandedMessage replaceBytesInRange:NSMakeRange(message.length + 1, 1) withBytes:&end];
       message = expandedMessage;
     }
-    decoded = [NSJSONSerialization JSONObjectWithData:message options:0 error:nil];
+    decoded = [NSJSONSerialization JSONObjectWithData:message options:0 error:&error];
   }
-  NSAssert(decoded, @"Invalid JSON message, decoding failed");
+  NSAssert(decoded, @"Invalid JSON message, decoding failed: %@", error);
   return isSimpleValue ? ((NSArray*)decoded)[0] : decoded;
 }
 @end
diff --git a/shell/platform/darwin/common/framework/Source/flutter_codecs_unittest.mm b/shell/platform/darwin/common/framework/Source/flutter_codecs_unittest.mm
index f0298a0c268f5..c9ab8fdaaac52 100644
--- a/shell/platform/darwin/common/framework/Source/flutter_codecs_unittest.mm
+++ b/shell/platform/darwin/common/framework/Source/flutter_codecs_unittest.mm
@@ -44,11 +44,26 @@
   ASSERT_TRUE([value isEqualTo:decoded]);
 }
 
+TEST(FlutterJSONCodec, ThrowsOnInvalidEncode) {
+  NSString* value = [[NSString alloc] initWithBytes:"\xdf\xff"
+                                             length:2
+                                           encoding:NSUTF16StringEncoding];
+  FlutterJSONMessageCodec* codec = [FlutterJSONMessageCodec sharedInstance];
+  EXPECT_EXIT([codec encode:value], testing::KilledBySignal(SIGABRT), "failed to convert to UTF8");
+}
+
 TEST(FlutterJSONCodec, CanDecodeZeroLength) {
   FlutterJSONMessageCodec* codec = [FlutterJSONMessageCodec sharedInstance];
   ASSERT_TRUE([codec decode:[NSData data]] == nil);
 }
 
+TEST(FlutterJSONCodec, ThrowsOnInvalidDecode) {
+  NSString* value = @"{{{";
+  FlutterJSONMessageCodec* codec = [FlutterJSONMessageCodec sharedInstance];
+  EXPECT_EXIT([codec decode:[value dataUsingEncoding:value.fastestEncoding]],
+              testing::KilledBySignal(SIGABRT), "No string key for value in object around line 1");
+}
+
 TEST(FlutterJSONCodec, CanEncodeAndDecodeNil) {
   FlutterJSONMessageCodec* codec = [FlutterJSONMessageCodec sharedInstance];
   ASSERT_TRUE([codec encode:nil] == nil);
diff --git a/testing/run_all_unittests.cc b/testing/run_all_unittests.cc
index 4213a9c754d9a..48f4c0d5eb816 100644
--- a/testing/run_all_unittests.cc
+++ b/testing/run_all_unittests.cc
@@ -49,6 +49,7 @@ int main(int argc, char** argv) {
 #endif  // FML_OS_IOS
 
   ::testing::InitGoogleTest(&argc, argv);
+  GTEST_FLAG_SET(death_test_style, "threadsafe");
 
   // Check if the user has specified a timeout.
   const auto timeout = GetTestTimeout();