1 files changed, 94 insertions, 0 deletions
diff --git a/third_party/rust/anyhow/tests/test_fmt.rs b/third_party/rust/anyhow/tests/test_fmt.rs
new file mode 100644
index 0000000000..cc4929197d
--- /dev/null
+++ b/third_party/rust/anyhow/tests/test_fmt.rs
@@ -0,0 +1,94 @@
+use anyhow::{bail, Context, Result};
+use std::io;
+
+fn f() -> Result<()> {
+    bail!(io::Error::new(io::ErrorKind::PermissionDenied, "oh no!"));
+}
+
+fn g() -> Result<()> {
+    f().context("f failed")
+}
+
+fn h() -> Result<()> {
+    g().context("g failed")
+}
+
+const EXPECTED_ALTDISPLAY_F: &str = "oh no!";
+
+const EXPECTED_ALTDISPLAY_G: &str = "f failed: oh no!";
+
+const EXPECTED_ALTDISPLAY_H: &str = "g failed: f failed: oh no!";
+
+const EXPECTED_DEBUG_F: &str = "oh no!";
+
+const EXPECTED_DEBUG_G: &str = "\
+f failed
+
+Caused by:
+    oh no!\
+";
+
+const EXPECTED_DEBUG_H: &str = "\
+g failed
+
+Caused by:
+    0: f failed
+    1: oh no!\
+";
+
+const EXPECTED_ALTDEBUG_F: &str = "\
+Custom {
+    kind: PermissionDenied,
+    error: \"oh no!\",
+}\
+";
+
+const EXPECTED_ALTDEBUG_G: &str = "\
+Error {
+    context: \"f failed\",
+    source: Custom {
+        kind: PermissionDenied,
+        error: \"oh no!\",
+    },
+}\
+";
+
+const EXPECTED_ALTDEBUG_H: &str = "\
+Error {
+    context: \"g failed\",
+    source: Error {
+        context: \"f failed\",
+        source: Custom {
+            kind: PermissionDenied,
+            error: \"oh no!\",
+        },
+    },
+}\
+";
+
+#[test]
+fn test_display() {
+    assert_eq!("g failed", h().unwrap_err().to_string());
+}
+
+#[test]
+fn test_altdisplay() {
+    assert_eq!(EXPECTED_ALTDISPLAY_F, format!("{:#}", f().unwrap_err()));
+    assert_eq!(EXPECTED_ALTDISPLAY_G, format!("{:#}", g().unwrap_err()));
+    assert_eq!(EXPECTED_ALTDISPLAY_H, format!("{:#}", h().unwrap_err()));
+}
+
+#[test]
+#[cfg_attr(not(backtrace), ignore)]
+fn test_debug() {
+    assert_eq!(EXPECTED_DEBUG_F, format!("{:?}", f().unwrap_err()));
+    assert_eq!(EXPECTED_DEBUG_G, format!("{:?}", g().unwrap_err()));
+    assert_eq!(EXPECTED_DEBUG_H, format!("{:?}", h().unwrap_err()));
+}
+
+#[test]
+fn test_altdebug() {
+    assert_eq!(EXPECTED_ALTDEBUG_F, format!("{:#?}", f().unwrap_err()));
+    assert_eq!(EXPECTED_ALTDEBUG_G, format!("{:#?}", g().unwrap_err()));
+    assert_eq!(EXPECTED_ALTDEBUG_H, format!("{:#?}", h().unwrap_err()));
+}