From ea0c7c9383db25f4e8f00442a15d601608ade56f Mon Sep 17 00:00:00 2001
From: Ben Noordhuis <info@bnoordhuis.nl>
Date: Fri, 9 Oct 2020 12:58:57 +0200
Subject: [PATCH] Fix PromiseRejectMessage::get_value() (#493)

Change its return type to `Option<Local<Value>>`. The C++ API
returns `Local<Value>` but that can be an empty handle.

Fixes #491
---
 src/promise.rs    |  3 +--
 tests/test_api.rs | 30 +++++++++++++++++++++++++++++-
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/src/promise.rs b/src/promise.rs
index 8ea85c9a..10517cd4 100644
--- a/src/promise.rs
+++ b/src/promise.rs
@@ -214,8 +214,7 @@ impl<'msg> PromiseRejectMessage<'msg> {
     unsafe { v8__PromiseRejectMessage__GetEvent(self) }
   }
 
-  pub fn get_value(&self) -> Local<'msg, Value> {
+  pub fn get_value(&self) -> Option<Local<'msg, Value>> {
     unsafe { Local::from_raw(v8__PromiseRejectMessage__GetValue(self)) }
-      .unwrap()
   }
 }
diff --git a/tests/test_api.rs b/tests/test_api.rs
index d17a797a..547e03e3 100644
--- a/tests/test_api.rs
+++ b/tests/test_api.rs
@@ -1674,7 +1674,7 @@ extern "C" fn promise_reject_callback(msg: v8::PromiseRejectMessage) {
   assert_eq!(event, v8::PromiseRejectEvent::PromiseRejectWithNoHandler);
   let promise = msg.get_promise();
   assert_eq!(promise.state(), v8::PromiseState::Rejected);
-  let value = msg.get_value();
+  let value = msg.get_value().unwrap();
   {
     let scope = &mut v8::HandleScope::new(scope);
     let value_str = value.to_string(scope).unwrap();
@@ -1698,6 +1698,34 @@ fn set_promise_reject_callback() {
   }
 }
 
+#[test]
+fn promise_reject_callback_no_value() {
+  extern "C" fn promise_reject_callback(m: v8::PromiseRejectMessage) {
+    use v8::PromiseRejectEvent::*;
+    let value = m.get_value();
+    match m.get_event() {
+      PromiseHandlerAddedAfterReject => assert!(value.is_none()),
+      PromiseRejectWithNoHandler => assert!(value.is_some()),
+      _ => unreachable!(),
+    };
+  }
+  let _setup_guard = setup();
+  let isolate = &mut v8::Isolate::new(Default::default());
+  isolate.set_promise_reject_callback(promise_reject_callback);
+  {
+    let scope = &mut v8::HandleScope::new(isolate);
+    let context = v8::Context::new(scope);
+    let scope = &mut v8::ContextScope::new(scope, context);
+    let source = r#"
+      function kaboom(resolve, reject) {
+        throw new Error("kaboom");
+      }
+      new Promise(kaboom).then(_ => {});
+    "#;
+    eval(scope, source).unwrap();
+  }
+}
+
 fn mock_script_origin<'s>(
   scope: &mut v8::HandleScope<'s>,
   resource_name_: &str,