From e68092b98e5e4a322d90f0f43520384ff39871b9 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Mon, 31 May 2021 14:37:41 +0100
Subject: [PATCH] childio: tests: Provide warning capture machinery

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 src/childio.rs | 42 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/src/childio.rs b/src/childio.rs
index 22059296..3e663c0e 100644
--- a/src/childio.rs
+++ b/src/childio.rs
@@ -114,10 +114,50 @@ impl<W> Write for ChildIo<W> where W: Write {
 
 #[cfg(test)]
 #[cfg(not(miri))]
-mod test {
+use crate::capture_warns_warn as warn;
+
+#[cfg(test)]
+#[cfg(not(miri))]
+pub mod test {
 use crate::prelude::*;
 use super::*;
 
+pub mod capture_warns {
+  use crate::prelude::*;
+  use std::cell::RefCell;
+
+  thread_local! {
+    pub static WARNINGS: RefCell<Option<Vec<String>>> = RefCell::new(None)
+  }
+
+  #[macro_export]
+  macro_rules! capture_warns_warn {
+    { $fmt:literal $($rhs:tt)* } => {
+      $crate::childio::test::capture_warns::WARNINGS.with(|w| {
+        let mut w = w.borrow_mut();
+        if let Some(ref mut msgs) = *w {
+          let s = format!($fmt $($rhs)*);
+          msgs.push(s);
+        } else {
+          crate::prelude::warn!($fmt $($rhs)*);
+        }
+      });
+    }
+  }
+
+  pub fn run(f: &dyn Fn()) -> Vec<String> {
+    WARNINGS.with(|w| {
+      let mut w =w.borrow_mut();
+      *w = Some(vec![]);
+    });
+    f();
+    WARNINGS.with(|w| {
+      let mut w =w.borrow_mut();
+      mem::take(&mut *w).unwrap()
+    })
+  }
+}
+
 #[test]
 fn t_cat() {
   let setup = ||{
-- 
2.30.2