fix: Don't write to tmpdir in CI

Skip writing to temporary file in CI
which is then typically inaccessible from an already failed
CI job. In those cases, it's better to dump directly to stderr,
since that'll typically be captured by console logging.

Inspired by zizmor

Author: epage

src/panic.rs

@@ -19,7 +19,7 @@ pub fn setup_panic(meta: impl Fn() -> Metadata) {
 
             panic::set_hook(Box::new(move |info: &PanicHookInfo<'_>| {
                 let report = Report::with_panic(&meta, info);
-                let file_path = report.persist().ok();
+                let file_path = if is_ci() { None } else { report.persist().ok() };
                 if file_path.is_none() {
                     use std::io::Write as _;
                     let stderr = std::io::stderr();
@@ -40,6 +40,11 @@ pub fn setup_panic(meta: impl Fn() -> Metadata) {
     }
 }
 
+/// Returns whether we are running in a CI environment.
+fn is_ci() -> bool {
+    std::env::var_os("CI").is_some()
+}
+
 /// Style of panic to be used
 #[non_exhaustive]
 #[derive(Copy, Clone, PartialEq, Eq)]

tests/single-panic/tests/integration.rs

@@ -127,11 +127,22 @@ fn release_with_ci() {
         .env("CI", "1")
         .assert()
         .stderr_eq(snapbox::str![[r#"
+name = "single-panic-test"
+operating_system = "[..]"
+crate_version = "0.1.0"
+explanation = """
+Panic occurred in file 'tests/single-panic/src/main.rs' at line 27
+"""
+cause = "OMG EVERYTHING IS ON FIRE!!!"
+method = "Panic"
+backtrace = [..]
+...
+
 Well, this is embarrassing.
 
 single-panic-test had a problem and crashed. To help us diagnose the problem you can send us a crash report.
 
-We have generated a report file at "[..].toml". Submit an issue or email with the subject of "single-panic-test Crash Report" and include the report as an attachment.
+We have generated a report file at "<Failed to store file to disk>". Submit an issue or email with the subject of "single-panic-test Crash Report" and include the report as an attachment.
 
 - Authors: Human Panic Authors <human-panic-crate@example.com>
 
@@ -144,7 +155,7 @@ Thank you kindly!
 
     #[cfg(unix)]
     {
-        let mut files = root_path
+        let files = root_path
             .read_dir()
             .unwrap()
             .map(|e| {
@@ -154,26 +165,7 @@ Thank you kindly!
                 (path, content)
             })
             .collect::<Vec<_>>();
-        assert_eq!(files.len(), 1, "{files:?}");
-        let (_, report) = files.pop().unwrap();
-        let report = report.unwrap();
-        snapbox::assert_data_eq!(
-            report,
-            snapbox::str![[r#"
-name = "single-panic-test"
-operating_system = "[..]"
-crate_version = "0.1.0"
-explanation = """
-Panic occurred in file 'tests/single-panic/src/main.rs' at line [..]
-"""
-cause = "OMG EVERYTHING IS ON FIRE!!!"
-method = "Panic"
-backtrace = """
-...
-"""
-
-"#]]
-        );
+        assert_eq!(files.len(), 0, "{files:?}");
     }
 
     root.close().unwrap();