From 6f1d7d11ce49040eafe54e5ff2da379be4d998c2 Mon Sep 17 00:00:00 2001
From: Hans Larsen <hans@larsen.online>
Date: Fri, 2 Aug 2024 17:42:51 -0700
Subject: [PATCH] Add a JsError::from_rust constructor to create native errors
 from Rust (#3921)

* Add a JsError::from_std constructor to create native errors from Rust

* Address comment
---
 core/engine/src/error.rs | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/core/engine/src/error.rs b/core/engine/src/error.rs
index a22780bd85..a1b28ce792 100644
--- a/core/engine/src/error.rs
+++ b/core/engine/src/error.rs
@@ -1,7 +1,5 @@
 //! Error-related types and conversions.
 
-use std::{error, fmt};
-
 use crate::{
     builtins::{error::ErrorObject, Array},
     js_string,
@@ -12,6 +10,7 @@ use crate::{
 };
 use boa_gc::{custom_trace, Finalize, Trace};
 use boa_macros::js_str;
+use std::{error, fmt};
 use thiserror::Error;
 
 /// Create an opaque error object from a value or string literal.
@@ -188,6 +187,29 @@ impl JsError {
         }
     }
 
+    /// Creates a new `JsError` from a Rust standard error `err`.
+    /// This will create a new `JsNativeError` with the message of the standard error.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use boa_engine::JsError;
+    /// let error = std::io::Error::new(std::io::ErrorKind::Other, "oh no!");
+    /// let js_error: JsError = JsError::from_rust(error);
+    ///
+    /// assert_eq!(js_error.as_native().unwrap().message(), "oh no!");
+    /// assert!(js_error.as_native().unwrap().cause().is_none());
+    /// ```
+    #[must_use]
+    pub fn from_rust(err: impl error::Error) -> Self {
+        let mut native_err = JsNativeError::error().with_message(err.to_string());
+        if let Some(source) = err.source() {
+            native_err = native_err.with_cause(Self::from_rust(source));
+        }
+
+        Self::from_native(native_err)
+    }
+
     /// Creates a new `JsError` from an opaque error `value`.
     ///
     /// # Examples