From 55f7f2a50d6e560fc712c18972fa5b1d11525ffb Mon Sep 17 00:00:00 2001
From: Rain <rain@sunshowers.io>
Date: Thu, 21 Sep 2023 15:14:15 -0700
Subject: [PATCH] [nextest-runner] on exec fail, stash error into stderr

A bit of a hack but a thoughtful one.
---
 Cargo.lock                   |  7 +++++++
 nextest-runner/Cargo.toml    |  1 +
 nextest-runner/src/runner.rs | 25 ++++++++++++++++---------
 3 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 3c0b8d8538b..0d80d490c32 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -592,6 +592,12 @@ version = "0.1.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "56254986775e3233ffa9c4d7d3faaf6d36a2c09d30b20687e9f88bc8bafc16c8"
 
+[[package]]
+name = "display-error-chain"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f77af9e75578c1ab34f5f04545a8b05be0c36fbd7a9bb3cf2d2a971e435fdbb9"
+
 [[package]]
 name = "duct"
 version = "0.13.6"
@@ -1526,6 +1532,7 @@ dependencies = [
  "config",
  "console-subscriber",
  "debug-ignore",
+ "display-error-chain",
  "duct",
  "dunce",
  "either",
diff --git a/nextest-runner/Cargo.toml b/nextest-runner/Cargo.toml
index 1f651ed6ead..f35f738ff46 100644
--- a/nextest-runner/Cargo.toml
+++ b/nextest-runner/Cargo.toml
@@ -24,6 +24,7 @@ cargo_metadata = "0.17.0"
 cfg-if = "1.0.0"
 chrono = "0.4.31"
 debug-ignore = "1.0.5"
+display-error-chain = "0.2.0"
 either = "1.9.0"
 futures = "0.3.28"
 guppy = "0.17.1"
diff --git a/nextest-runner/src/runner.rs b/nextest-runner/src/runner.rs
index 43fe92a4971..ee85614c116 100644
--- a/nextest-runner/src/runner.rs
+++ b/nextest-runner/src/runner.rs
@@ -19,12 +19,14 @@ use crate::{
 };
 use async_scoped::TokioScope;
 use bytes::Bytes;
+use display_error_chain::DisplayErrorChain;
 use future_queue::StreamExt;
 use futures::{future::try_join, prelude::*};
 use nextest_metadata::{FilterMatch, MismatchReason};
 use rand::{distributions::OpenClosed01, thread_rng, Rng};
 use std::{
     convert::Infallible,
+    fmt::Write,
     marker::PhantomData,
     num::NonZeroUsize,
     process::Stdio,
@@ -628,15 +630,20 @@ impl<'a> TestRunnerInner<'a> {
             .await
         {
             Ok(run_status) => run_status,
-            Err(_) => InternalExecuteStatus {
-                // TODO: can we return more information in stdout/stderr? investigate this
-                stdout: Bytes::new(),
-                stderr: Bytes::new(),
-                result: ExecutionResult::ExecFail,
-                stopwatch_end: stopwatch.end(),
-                is_slow: false,
-                delay_before_start,
-            },
+            Err(error) => {
+                // Put the error chain inside stderr.
+                let mut stderr = bytes::BytesMut::new();
+                writeln!(&mut stderr, "{}", DisplayErrorChain::new(error)).unwrap();
+
+                InternalExecuteStatus {
+                    stdout: Bytes::new(),
+                    stderr: stderr.freeze(),
+                    result: ExecutionResult::ExecFail,
+                    stopwatch_end: stopwatch.end(),
+                    is_slow: false,
+                    delay_before_start,
+                }
+            }
         }
     }