status: add error source in more cases

tonic/src/status.rs

@@ -306,7 +306,11 @@ impl Status {
     #[cfg_attr(not(feature = "transport"), allow(dead_code))]
     pub(crate) fn from_error(err: Box<dyn Error + Send + Sync + 'static>) -> Status {
         Status::try_from_error(err)
-            .unwrap_or_else(|err| Status::new(Code::Unknown, err.to_string()))
+            .unwrap_or_else(|err| {
+                let mut status = Status::new(Code::Unknown, err.to_string());
+                status.source = Some(err);
+                status
+            })
     }
 
     pub(crate) fn try_from_error(
@@ -628,7 +632,9 @@ impl From<std::io::Error> for Status {
             ErrorKind::UnexpectedEof => Code::OutOfRange,
             _ => Code::Unknown,
         };
-        Status::new(code, err.to_string())
+        let mut status = Status::new(code, err.to_string());
+        status.source = Some(Box::new(err));
+        status
     }
 }
 
@@ -801,6 +807,8 @@ impl From<Code> for i32 {
 
 #[cfg(test)]
 mod tests {
+    use std::io;
+
     use super::*;
     use crate::Error;
 
@@ -830,11 +838,33 @@ mod tests {
 
     #[test]
     fn from_error_unknown() {
+        use std::error::Error as _;
+
         let orig: Error = "peek-a-boo".into();
         let found = Status::from_error(orig);
 
         assert_eq!(found.code(), Code::Unknown);
         assert_eq!(found.message(), "peek-a-boo".to_string());
+        assert_eq!(found.source().unwrap().to_string(), "peek-a-boo");
+    }
+
+    #[test]
+    fn from_error_io() {
+        use std::error::Error as _;
+
+        let orig: Error = "in-use".into();
+        let io_orig = io::Error::new(io::ErrorKind::AddrInUse, orig);
+        let found: Status = io_orig.into();
+
+        assert_eq!(found.code(), Code::Unavailable);
+        assert_eq!(found.message(), "in-use".to_string());
+
+        let source = found
+            .source()
+            .and_then(|err| err.downcast_ref::<io::Error>())
+            .unwrap();
+        assert_eq!(source.to_string(), "in-use");
+        assert_eq!(source.kind(), io::ErrorKind::AddrInUse);
     }
 
     #[test]