Merge pull request #849 from napi-rs/promise

feat(napi): await Promise<T> in async fn

crates/backend/src/codegen/enum.rs

@@ -109,7 +109,7 @@ impl NapiEnum {
 
       define_properties.push(quote! {
         {
-          let name = CString::new(#name_lit).unwrap();
+          let name = CString::new(#name_lit)?;
           napi::bindgen_prelude::check_status!(
             napi::bindgen_prelude::sys::napi_set_named_property(env, obj_ptr, name.as_ptr(), i32::to_napi_value(env, #val_lit)?),
             "Failed to defined enum `{}`",

crates/backend/src/typegen.rs

@@ -155,6 +155,8 @@ pub fn ty_to_ts_type(ty: &Type, is_return_ty: bool) -> String {
           .with(|c| c.borrow_mut().get(rust_ty.as_str()).cloned())
         {
           ts_ty = Some(t);
+        } else if rust_ty == "Promise" {
+          ts_ty = Some(format!("Promise<{}>", args.first().unwrap()));
         } else {
           // there should be runtime registered type in else
           ts_ty = Some(rust_ty);

crates/napi/src/async_work.rs

@@ -59,11 +59,12 @@ pub fn run<T: Task>(
     napi_async_work: ptr::null_mut(),
     status: task_status.clone(),
   }));
+  let async_work_name = CString::new("napi_rs_async_work")?;
   check_status!(unsafe {
     sys::napi_create_async_work(
       env,
       raw_resource,
-      CString::new("napi_rs_async_work")?.as_ptr() as *mut _,
+      async_work_name.as_ptr() as *mut _,
       Some(execute::<T> as unsafe extern "C" fn(env: sys::napi_env, data: *mut c_void)),
       Some(
         complete::<T>

crates/napi/src/bindgen_runtime/js_values.rs

@@ -13,6 +13,7 @@ mod map;
 mod nil;
 mod number;
 mod object;
+mod promise;
 #[cfg(feature = "serde-json")]
 mod serde;
 mod string;
@@ -27,6 +28,7 @@ pub use either::*;
 pub use function::*;
 pub use nil::*;
 pub use object::*;
+pub use promise::*;
 pub use string::*;
 pub use task::*;
 

crates/napi/src/bindgen_runtime/js_values/promise.rs

@@ -0,0 +1,170 @@
+use std::ffi::{c_void, CString};
+use std::future;
+use std::pin::Pin;
+use std::ptr;
+use std::task::{Context, Poll};
+
+use tokio::sync::oneshot::{channel, Receiver, Sender};
+
+use crate::{check_status, Error, Result, Status};
+
+use super::FromNapiValue;
+
+pub struct Promise<T: FromNapiValue> {
+  value: Pin<Box<Receiver<*mut Result<T>>>>,
+}
+
+unsafe impl<T: FromNapiValue> Send for Promise<T> {}
+unsafe impl<T: FromNapiValue> Sync for Promise<T> {}
+
+impl<T: FromNapiValue> FromNapiValue for Promise<T> {
+  unsafe fn from_napi_value(
+    env: napi_sys::napi_env,
+    napi_val: napi_sys::napi_value,
+  ) -> crate::Result<Self> {
+    let mut then = ptr::null_mut();
+    let then_c_string = CString::new("then")?;
+    check_status!(
+      napi_sys::napi_get_named_property(env, napi_val, then_c_string.as_ptr(), &mut then,),
+      "Failed to get then function"
+    )?;
+    let mut promise_after_then = ptr::null_mut();
+    let mut then_js_cb = ptr::null_mut();
+    let (tx, rx) = channel();
+    let tx_ptr = Box::into_raw(Box::new(tx));
+    check_status!(
+      napi_sys::napi_create_function(
+        env,
+        then_c_string.as_ptr(),
+        4,
+        Some(then_callback::<T>),
+        tx_ptr as *mut _,
+        &mut then_js_cb,
+      ),
+      "Failed to create then callback"
+    )?;
+    check_status!(
+      napi_sys::napi_call_function(
+        env,
+        napi_val,
+        then,
+        1,
+        [then_js_cb].as_ptr(),
+        &mut promise_after_then,
+      ),
+      "Failed to call then method"
+    )?;
+    let mut catch = ptr::null_mut();
+    let catch_c_string = CString::new("catch")?;
+    check_status!(
+      napi_sys::napi_get_named_property(
+        env,
+        promise_after_then,
+        catch_c_string.as_ptr(),
+        &mut catch
+      ),
+      "Failed to get then function"
+    )?;
+    let mut catch_js_cb = ptr::null_mut();
+    check_status!(
+      napi_sys::napi_create_function(
+        env,
+        catch_c_string.as_ptr(),
+        5,
+        Some(catch_callback::<T>),
+        tx_ptr as *mut c_void,
+        &mut catch_js_cb
+      ),
+      "Failed to create catch callback"
+    )?;
+    check_status!(
+      napi_sys::napi_call_function(
+        env,
+        promise_after_then,
+        catch,
+        1,
+        [catch_js_cb].as_ptr(),
+        ptr::null_mut()
+      ),
+      "Failed to call catch method"
+    )?;
+    Ok(Promise {
+      value: Box::pin(rx),
+    })
+  }
+}
+
+impl<T: FromNapiValue> future::Future for Promise<T> {
+  type Output = Result<T>;
+
+  fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+    match self.value.as_mut().poll(cx) {
+      Poll::Pending => Poll::Pending,
+      Poll::Ready(v) => Poll::Ready(
+        v.map_err(|e| Error::new(Status::GenericFailure, format!("{}", e)))
+          .and_then(|v| unsafe { *Box::from_raw(v) }.map_err(Error::from)),
+      ),
+    }
+  }
+}
+
+unsafe extern "C" fn then_callback<T: FromNapiValue>(
+  env: napi_sys::napi_env,
+  info: napi_sys::napi_callback_info,
+) -> napi_sys::napi_value {
+  let mut data = ptr::null_mut();
+  let mut resolved_value: [napi_sys::napi_value; 1] = [ptr::null_mut()];
+  let mut this = ptr::null_mut();
+  let get_cb_status = napi_sys::napi_get_cb_info(
+    env,
+    info,
+    &mut 1,
+    resolved_value.as_mut_ptr(),
+    &mut this,
+    &mut data,
+  );
+  debug_assert!(
+    get_cb_status == napi_sys::Status::napi_ok,
+    "Get callback info from Promise::then failed"
+  );
+  let resolve_value_t = Box::new(T::from_napi_value(env, resolved_value[0]));
+  let sender = Box::from_raw(data as *mut Sender<*mut Result<T>>);
+  sender
+    .send(Box::into_raw(resolve_value_t))
+    .expect("Send Promise resolved value error");
+  this
+}
+
+unsafe extern "C" fn catch_callback<T: FromNapiValue>(
+  env: napi_sys::napi_env,
+  info: napi_sys::napi_callback_info,
+) -> napi_sys::napi_value {
+  let mut data = ptr::null_mut();
+  let mut rejected_value: [napi_sys::napi_value; 1] = [ptr::null_mut()];
+  let mut this = ptr::null_mut();
+  let mut argc = 1;
+  let get_cb_status = napi_sys::napi_get_cb_info(
+    env,
+    info,
+    &mut argc,
+    rejected_value.as_mut_ptr(),
+    &mut this,
+    &mut data,
+  );
+  debug_assert!(
+    get_cb_status == napi_sys::Status::napi_ok,
+    "Get callback info from Promise::catch failed"
+  );
+  let rejected_value = rejected_value[0];
+  let mut error_ref = ptr::null_mut();
+  let create_ref_status = napi_sys::napi_create_reference(env, rejected_value, 1, &mut error_ref);
+  debug_assert!(
+    create_ref_status == napi_sys::Status::napi_ok,
+    "Create Error reference failed"
+  );
+  let sender = Box::from_raw(data as *mut Sender<*mut Result<T>>);
+  sender
+    .send(Box::into_raw(Box::new(Err(Error::from(error_ref)))))
+    .expect("Send Promise resolved value error");
+  this
+}

crates/napi/src/call_context.rs

@@ -47,10 +47,10 @@ impl<'env> CallContext<'env> {
 
   pub fn get<ArgType: NapiValue>(&self, index: usize) -> Result<ArgType> {
     if index >= self.arg_len() {
-      Err(Error {
+      Err(Error::new(
-        status: Status::GenericFailure,
+        Status::GenericFailure,
-        reason: "Arguments index out of range".to_owned(),
+        "Arguments index out of range".to_owned(),
-      })
+      ))
     } else {
       Ok(unsafe { ArgType::from_raw_unchecked(self.env.0, self.args[index]) })
     }
@@ -58,10 +58,10 @@ impl<'env> CallContext<'env> {
 
   pub fn try_get<ArgType: NapiValue>(&self, index: usize) -> Result<Either<ArgType, JsUndefined>> {
     if index >= self.arg_len() {
-      Err(Error {
+      Err(Error::new(
-        status: Status::GenericFailure,
+        Status::GenericFailure,
-        reason: "Arguments index out of range".to_owned(),
+        "Arguments index out of range".to_owned(),
-      })
+      ))
     } else if index < self.length {
       unsafe { ArgType::from_raw(self.env.0, self.args[index]) }.map(Either::A)
     } else {

crates/napi/src/env.rs

@@ -629,42 +629,39 @@ impl Env {
 
   /// This API throws a JavaScript Error with the text provided.
   pub fn throw_error(&self, msg: &str, code: Option<&str>) -> Result<()> {
+    let code = code.and_then(|s| CString::new(s).ok());
+    let msg = CString::new(msg)?;
     check_status!(unsafe {
       sys::napi_throw_error(
         self.0,
-        match code {
+        code.map(|s| s.as_ptr()).unwrap_or(ptr::null_mut()),
-          Some(s) => CString::new(s)?.as_ptr(),
+        msg.as_ptr(),
-          None => ptr::null_mut(),
-        },
-        CString::new(msg)?.as_ptr(),
       )
     })
   }
 
   /// This API throws a JavaScript RangeError with the text provided.
   pub fn throw_range_error(&self, msg: &str, code: Option<&str>) -> Result<()> {
+    let code = code.and_then(|s| CString::new(s).ok());
+    let msg = CString::new(msg)?;
     check_status!(unsafe {
       sys::napi_throw_range_error(
         self.0,
-        match code {
+        code.map(|s| s.as_ptr()).unwrap_or(ptr::null_mut()),
-          Some(s) => CString::new(s)?.as_ptr(),
+        msg.as_ptr(),
-          None => ptr::null_mut(),
-        },
-        CString::new(msg)?.as_ptr(),
       )
     })
   }
 
   /// This API throws a JavaScript TypeError with the text provided.
   pub fn throw_type_error(&self, msg: &str, code: Option<&str>) -> Result<()> {
+    let code = code.and_then(|s| CString::new(s).ok());
+    let msg = CString::new(msg)?;
     check_status!(unsafe {
       sys::napi_throw_type_error(
         self.0,
-        match code {
+        code.map(|s| s.as_ptr()).unwrap_or(ptr::null_mut()),
-          Some(s) => CString::new(s)?.as_ptr(),
+        msg.as_ptr(),
-          None => ptr::null_mut(),
-        },
-        CString::new(msg)?.as_ptr(),
       )
     })
   }
@@ -714,11 +711,11 @@ impl Env {
       .iter()
       .map(|prop| prop.raw())
       .collect::<Vec<sys::napi_property_descriptor>>();
-
+    let c_name = CString::new(name)?;
     check_status!(unsafe {
       sys::napi_define_class(
         self.0,
-        name.as_ptr() as *const c_char,
+        c_name.as_ptr() as *const c_char,
         name.len(),
         Some(constructor_cb),
         ptr::null_mut(),
@@ -756,15 +753,17 @@ impl Env {
       let type_id = unknown_tagged_object as *const TypeId;
       if *type_id == TypeId::of::<T>() {
         let tagged_object = unknown_tagged_object as *mut TaggedObject<T>;
-        (*tagged_object).object.as_mut().ok_or(Error {
+        (*tagged_object).object.as_mut().ok_or_else(|| {
-          status: Status::InvalidArg,
+          Error::new(
-          reason: "Invalid argument, nothing attach to js_object".to_owned(),
+            Status::InvalidArg,
+            "Invalid argument, nothing attach to js_object".to_owned(),
+          )
         })
       } else {
-        Err(Error {
+        Err(Error::new(
-          status: Status::InvalidArg,
+          Status::InvalidArg,
-          reason: "Invalid argument, T on unrwap is not the type of wrapped object".to_owned(),
+          "Invalid argument, T on unrwap is not the type of wrapped object".to_owned(),
-        })
+        ))
       }
     }
   }
@@ -781,15 +780,17 @@ impl Env {
       let type_id = unknown_tagged_object as *const TypeId;
       if *type_id == TypeId::of::<T>() {
         let tagged_object = unknown_tagged_object as *mut TaggedObject<T>;
-        (*tagged_object).object.as_mut().ok_or(Error {
+        (*tagged_object).object.as_mut().ok_or_else(|| {
-          status: Status::InvalidArg,
+          Error::new(
-          reason: "Invalid argument, nothing attach to js_object".to_owned(),
+            Status::InvalidArg,
+            "Invalid argument, nothing attach to js_object".to_owned(),
+          )
         })
       } else {
-        Err(Error {
+        Err(Error::new(
-          status: Status::InvalidArg,
+          Status::InvalidArg,
-          reason: "Invalid argument, T on unrwap is not the type of wrapped object".to_owned(),
+          "Invalid argument, T on unrwap is not the type of wrapped object".to_owned(),
-        })
+        ))
       }
     }
   }
@@ -807,10 +808,10 @@ impl Env {
         Box::from_raw(unknown_tagged_object as *mut TaggedObject<T>);
         Ok(())
       } else {
-        Err(Error {
+        Err(Error::new(
-          status: Status::InvalidArg,
+          Status::InvalidArg,
-          reason: "Invalid argument, T on unrwap is not the type of wrapped object".to_owned(),
+          "Invalid argument, T on unrwap is not the type of wrapped object".to_owned(),
-        })
+        ))
       }
     }
   }
@@ -905,15 +906,17 @@ impl Env {
       let type_id = unknown_tagged_object as *const TypeId;
       if *type_id == TypeId::of::<T>() {
         let tagged_object = unknown_tagged_object as *mut TaggedObject<T>;
-        (*tagged_object).object.as_mut().ok_or(Error {
+        (*tagged_object).object.as_mut().ok_or_else(|| {
-          status: Status::InvalidArg,
+          Error::new(
-          reason: "nothing attach to js_external".to_owned(),
+            Status::InvalidArg,
+            "nothing attach to js_external".to_owned(),
+          )
         })
       } else {
-        Err(Error {
+        Err(Error::new(
-          status: Status::InvalidArg,
+          Status::InvalidArg,
-          reason: "T on get_value_external is not the type of wrapped object".to_owned(),
+          "T on get_value_external is not the type of wrapped object".to_owned(),
-        })
+        ))
       }
     }
   }
@@ -1103,15 +1106,17 @@ impl Env {
       }
       if *type_id == TypeId::of::<T>() {
         let tagged_object = unknown_tagged_object as *mut TaggedObject<T>;
-        (*tagged_object).object.as_mut().map(Some).ok_or(Error {
+        (*tagged_object).object.as_mut().map(Some).ok_or_else(|| {
-          status: Status::InvalidArg,
+          Error::new(
-          reason: "Invalid argument, nothing attach to js_object".to_owned(),
+            Status::InvalidArg,
+            "Invalid argument, nothing attach to js_object".to_owned(),
+          )
         })
       } else {
-        Err(Error {
+        Err(Error::new(
-          status: Status::InvalidArg,
+          Status::InvalidArg,
-          reason: "Invalid argument, T on unrwap is not the type of wrapped object".to_owned(),
+          "Invalid argument, T on unrwap is not the type of wrapped object".to_owned(),
-        })
+        ))
       }
     }
   }

crates/napi/src/error.rs

@@ -23,8 +23,14 @@ pub type Result<T> = std::result::Result<T, Error>;
 pub struct Error {
   pub status: Status,
   pub reason: String,
+  // Convert raw `JsError` into Error
+  // Only be used in `async fn(p: Promise<T>)` scenario
+  pub(crate) maybe_raw: sys::napi_ref,
 }
 
+unsafe impl Send for Error {}
+unsafe impl Sync for Error {}
+
 impl error::Error for Error {}
 
 #[cfg(feature = "serde-json")]
@@ -48,6 +54,16 @@ impl From<SerdeJSONError> for Error {
   }
 }
 
+impl From<sys::napi_ref> for Error {
+  fn from(value: sys::napi_ref) -> Self {
+    Self {
+      status: Status::InvalidArg,
+      reason: "".to_string(),
+      maybe_raw: value,
+    }
+  }
+}
+
 impl fmt::Display for Error {
   fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     if !self.reason.is_empty() {
@@ -60,13 +76,18 @@ impl fmt::Display for Error {
 
 impl Error {
   pub fn new(status: Status, reason: String) -> Self {
-    Error { status, reason }
+    Error {
+      status,
+      reason,
+      maybe_raw: ptr::null_mut(),
+    }
   }
 
   pub fn from_status(status: Status) -> Self {
     Error {
       status,
       reason: "".to_owned(),
+      maybe_raw: ptr::null_mut(),
     }
   }
 
@@ -74,6 +95,7 @@ impl Error {
     Error {
       status: Status::GenericFailure,
       reason,
+      maybe_raw: ptr::null_mut(),
     }
   }
 }
@@ -83,6 +105,7 @@ impl From<std::ffi::NulError> for Error {
     Error {
       status: Status::GenericFailure,
       reason: format!("{}", error),
+      maybe_raw: ptr::null_mut(),
     }
   }
 }
@@ -92,6 +115,7 @@ impl From<std::io::Error> for Error {
     Error {
       status: Status::GenericFailure,
       reason: format!("{}", error),
+      maybe_raw: ptr::null_mut(),
     }
   }
 }
@@ -163,8 +187,10 @@ macro_rules! impl_object_methods {
       pub unsafe fn throw_into(self, env: sys::napi_env) {
         #[cfg(debug_assertions)]
         let reason = self.0.reason.clone();
-        #[cfg(debug_assertions)]
         let status = self.0.status;
+        if status == Status::PendingException {
+          return;
+        }
         let js_error = self.into_value(env);
         #[cfg(debug_assertions)]
         let throw_status = sys::napi_throw(env, js_error);

crates/napi/src/js_values/mod.rs

@@ -306,7 +306,7 @@ macro_rules! impl_object_methods {
       pub fn create_named_method(&mut self, name: &str, function: Callback) -> Result<()> {
         let mut js_function = ptr::null_mut();
         let len = name.len();
-        let name = CString::new(name.as_bytes())?;
+        let name = CString::new(name)?;
         check_status!(unsafe {
           sys::napi_create_function(
             self.0.env,

crates/napi/src/lib.rs

@@ -155,6 +155,35 @@ macro_rules! assert_type_of {
   };
 }
 
+#[allow(dead_code)]
+#[cfg(debug_assertions)]
+pub(crate) unsafe fn log_js_value<V: AsRef<[sys::napi_value]>>(
+  // `info`, `log`, `warning` or `error`
+  method: &str,
+  env: sys::napi_env,
+  values: V,
+) {
+  use std::ffi::CString;
+  use std::ptr;
+
+  let mut g = ptr::null_mut();
+  sys::napi_get_global(env, &mut g);
+  let mut console = ptr::null_mut();
+  let console_c_string = CString::new("console").unwrap();
+  let method_c_string = CString::new(method).unwrap();
+  sys::napi_get_named_property(env, g, console_c_string.as_ptr(), &mut console);
+  let mut method_js_fn = ptr::null_mut();
+  sys::napi_get_named_property(env, console, method_c_string.as_ptr(), &mut method_js_fn);
+  sys::napi_call_function(
+    env,
+    console,
+    method_js_fn,
+    values.as_ref().len(),
+    values.as_ref().as_ptr(),
+    ptr::null_mut(),
+  );
+}
+
 pub mod bindgen_prelude {
   #[cfg(feature = "compat-mode")]
   pub use crate::bindgen_runtime::register_module_exports;

crates/napi/src/promise.rs

@@ -1,6 +1,7 @@
+use std::ffi::CString;
 use std::future::Future;
 use std::marker::PhantomData;
-use std::os::raw::{c_char, c_void};
+use std::os::raw::c_void;
 use std::ptr;
 
 use crate::{check_status, sys, JsError, Result};
@@ -12,7 +13,6 @@ pub struct FuturePromise<Data, Resolver: FnOnce(sys::napi_env, Data) -> Result<s
   async_resource_name: sys::napi_value,
   resolver: Resolver,
   _data: PhantomData<Data>,
-  _value: PhantomData<sys::napi_value>,
 }
 
 unsafe impl<T, F: FnOnce(sys::napi_env, T) -> Result<sys::napi_value>> Send
@@ -23,26 +23,20 @@ unsafe impl<T, F: FnOnce(sys::napi_env, T) -> Result<sys::napi_value>> Send
 impl<Data, Resolver: FnOnce(sys::napi_env, Data) -> Result<sys::napi_value>>
   FuturePromise<Data, Resolver>
 {
-  pub fn new(env: sys::napi_env, dererred: sys::napi_deferred, resolver: Resolver) -> Result<Self> {
+  pub fn new(env: sys::napi_env, deferred: sys::napi_deferred, resolver: Resolver) -> Result<Self> {
     let mut async_resource_name = ptr::null_mut();
-    let s = "napi_resolve_promise_from_future";
+    let s = CString::new("napi_resolve_promise_from_future")?;
     check_status!(unsafe {
-      sys::napi_create_string_utf8(
+      sys::napi_create_string_utf8(env, s.as_ptr(), 32, &mut async_resource_name)
-        env,
-        s.as_ptr() as *const c_char,
-        s.len(),
-        &mut async_resource_name,
-      )
     })?;
 
     Ok(FuturePromise {
-      deferred: dererred,
+      deferred,
       resolver,
       env,
       tsfn: ptr::null_mut(),
       async_resource_name,
       _data: PhantomData,
-      _value: PhantomData,
     })
   }
 
@@ -83,7 +77,7 @@ pub(crate) async fn resolve_from_future<Data: Send, Fut: Future<Output = Result<
   check_status!(unsafe {
     sys::napi_call_threadsafe_function(
       tsfn_value.0,
-      Box::into_raw(Box::from(val)) as *mut Data as *mut c_void,
+      Box::into_raw(Box::from(val)) as *mut c_void,
       sys::napi_threadsafe_function_call_mode::napi_tsfn_nonblocking,
     )
   })
@@ -117,7 +111,26 @@ unsafe extern "C" fn call_js_cb<
       debug_assert!(status == sys::Status::napi_ok, "Resolve promise failed");
     }
     Err(e) => {
-      let status = sys::napi_reject_deferred(env, deferred, JsError::from(e).into_value(env));
+      let status = sys::napi_reject_deferred(
+        env,
+        deferred,
+        if e.maybe_raw.is_null() {
+          JsError::from(e).into_value(env)
+        } else {
+          let mut err = ptr::null_mut();
+          let get_err_status = sys::napi_get_reference_value(env, e.maybe_raw, &mut err);
+          debug_assert!(
+            get_err_status == sys::Status::napi_ok,
+            "Get Error from Reference failed"
+          );
+          let delete_reference_status = sys::napi_delete_reference(env, e.maybe_raw);
+          debug_assert!(
+            delete_reference_status == sys::Status::napi_ok,
+            "Delete Error Reference failed"
+          );
+          err
+        },
+      );
       debug_assert!(status == sys::Status::napi_ok, "Reject promise failed");
     }
   };

crates/napi/src/version.rs

@@ -19,10 +19,9 @@ impl TryFrom<sys::napi_node_version> for NodeVersion {
       minor: value.minor,
       patch: value.patch,
       release: unsafe {
-        CStr::from_ptr(value.release).to_str().map_err(|_| Error {
+        CStr::from_ptr(value.release)
-          status: Status::StringExpected,
+          .to_str()
-          reason: "Invalid release name".to_owned(),
+          .map_err(|_| Error::new(Status::StringExpected, "Invalid release name".to_owned()))?
-        })?
       },
     })
   }

examples/napi/__test__/typegen.spec.ts.md

@@ -34,6 +34,7 @@ Generated by [AVA](https://avajs.dev).
     export function fibonacci(n: number): number␊
     export function listObjKeys(obj: object): Array<string>␊
     export function createObj(): object␊
+    export function asyncPlus100(p: Promise<number>): Promise<number>␊
     interface PackageJson {␊
       name: string␊
       version: string␊

examples/napi/__test__/values.spec.ts

@@ -40,6 +40,7 @@ import {
   createBigIntI64,
   callThreadsafeFunction,
   threadsafeFunctionThrowError,
+  asyncPlus100,
 } from '../'
 
 test('number', (t) => {
@@ -238,10 +239,9 @@ BigIntTest('create BigInt i64', (t) => {
   t.is(createBigIntI64(), BigInt(100))
 })
 
-const ThreadsafeFunctionTest =
+const Napi4Test = Number(process.versions.napi) >= 4 ? test : test.skip
-  Number(process.versions.napi) >= 4 ? test : test.skip
 
-ThreadsafeFunctionTest('call thread safe function', (t) => {
+Napi4Test('call thread safe function', (t) => {
   let i = 0
   let value = 0
   return new Promise((resolve) => {
@@ -260,10 +260,26 @@ ThreadsafeFunctionTest('call thread safe function', (t) => {
   })
 })
 
-ThreadsafeFunctionTest('throw error from thread safe function', async (t) => {
+Napi4Test('throw error from thread safe function', async (t) => {
   const throwPromise = new Promise((_, reject) => {
     threadsafeFunctionThrowError(reject)
   })
   const err = await t.throwsAsync(throwPromise)
   t.is(err.message, 'ThrowFromNative')
 })
+
+Napi4Test('await Promise in rust', async (t) => {
+  const fx = 20
+  const result = await asyncPlus100(
+    new Promise((resolve) => {
+      setTimeout(() => resolve(fx), 50)
+    }),
+  )
+  t.is(result, fx + 100)
+})
+
+Napi4Test('Promise should reject raw error in rust', async (t) => {
+  const fxError = new Error('What is Happy Planet')
+  const err = await t.throwsAsync(() => asyncPlus100(Promise.reject(fxError)))
+  t.is(err, fxError)
+})

examples/napi/index.d.ts

@@ -24,6 +24,7 @@ export function add(a: number, b: number): number
 export function fibonacci(n: number): number
 export function listObjKeys(obj: object): Array<string>
 export function createObj(): object
+export function asyncPlus100(p: Promise<number>): Promise<number>
 interface PackageJson {
   name: string
   version: string

examples/napi/src/lib.rs

@@ -15,6 +15,7 @@ mod error;
 mod nullable;
 mod number;
 mod object;
+mod promise;
 mod serde;
 mod string;
 mod task;

examples/napi/src/promise.rs

@@ -0,0 +1,7 @@
+use napi::bindgen_prelude::*;
+
+#[napi]
+pub async fn async_plus_100(p: Promise<u32>) -> Result<u32> {
+  let v = p.await?;
+  Ok(v + 100)
+}