issue 2561, send all [bat error]s to stderr in default_error_handler

CHANGELOG.md

@@ -4,7 +4,10 @@
 
 ## Bugfixes
 
+- Send all bat error messages to stderr, see #2827 (@deboard)
+
 - Fix long file name wrapping in header, see #2835 (@FilipRazek)
+- 
 - Fix `NO_COLOR` support, see #2767 (@acuteenvy)
 
 ## Other

src/error.rs

@@ -67,7 +67,15 @@ pub fn default_error_handler(error: &Error, output: &mut dyn Write) {
             .ok();
         }
         _ => {
-            writeln!(output, "{}: {}", Red.paint("[bat error]"), error).ok();
+            // default - always write [bat error] to stderr
+            let stderr = std::io::stderr();
+            writeln!(
+                &mut stderr.lock(),
+                "{}: {}",
+                Red.paint("[bat error]"),
+                error
+            )
+            .ok();
         }
     };
 }

tests/integration_tests.rs

@@ -748,6 +748,16 @@ fn env_var_bat_pager_value_bat() {
         .stderr(predicate::str::contains("bat as a pager is disallowed"));
 }
 
+#[test]
+fn bat_error_to_stderr() {
+    bat()
+        .env("BAT_PAGER", "bat")
+        .arg("/tmp")
+        .assert()
+        .failure()
+        .stderr(predicate::str::contains("[bat error]"));
+}
+
 #[test]
 fn pager_value_bat() {
     bat()
@@ -1194,6 +1204,9 @@ fn can_print_file_starting_with_cache() {
         .stderr("");
 }
 
+#[test]
+fn send_all_bat_error_to_stderr() {}
+
 #[test]
 fn does_not_print_unwanted_file_named_cache() {
     bat_with_config().arg("cach").assert().failure();

tests/scripts/stderr1.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+
+## test for issue 2561
+
+OUTPUT=$(mktemp)
+BAT=bat
+code=$($BAT /tmp 2> $OUTPUT; cat $OUTPUT | grep error; echo $?)
+
+if [[ $code == 1 ]]; then
+    echo "stderr test fsil"
+    exit 1
+fi
+
+exit 0