1 files changed, 123 insertions, 0 deletions
diff --git a/third_party/rust/anyhow/tests/test_downcast.rs b/third_party/rust/anyhow/tests/test_downcast.rs
new file mode 100644
index 0000000000..b4470d551a
--- /dev/null
+++ b/third_party/rust/anyhow/tests/test_downcast.rs
@@ -0,0 +1,123 @@
+#![allow(clippy::assertions_on_result_states, clippy::wildcard_imports)]
+
+mod common;
+mod drop;
+
+use self::common::*;
+use self::drop::{DetectDrop, Flag};
+use anyhow::Error;
+use std::error::Error as StdError;
+use std::fmt::{self, Display};
+use std::io;
+
+#[test]
+fn test_downcast() {
+    assert_eq!(
+        "oh no!",
+        bail_literal().unwrap_err().downcast::<&str>().unwrap(),
+    );
+    assert_eq!(
+        "oh no!",
+        bail_fmt().unwrap_err().downcast::<String>().unwrap(),
+    );
+    assert_eq!(
+        "oh no!",
+        bail_error()
+            .unwrap_err()
+            .downcast::<io::Error>()
+            .unwrap()
+            .to_string(),
+    );
+}
+
+#[test]
+fn test_downcast_ref() {
+    assert_eq!(
+        "oh no!",
+        *bail_literal().unwrap_err().downcast_ref::<&str>().unwrap(),
+    );
+    assert_eq!(
+        "oh no!",
+        bail_fmt().unwrap_err().downcast_ref::<String>().unwrap(),
+    );
+    assert_eq!(
+        "oh no!",
+        bail_error()
+            .unwrap_err()
+            .downcast_ref::<io::Error>()
+            .unwrap()
+            .to_string(),
+    );
+}
+
+#[test]
+fn test_downcast_mut() {
+    assert_eq!(
+        "oh no!",
+        *bail_literal().unwrap_err().downcast_mut::<&str>().unwrap(),
+    );
+    assert_eq!(
+        "oh no!",
+        bail_fmt().unwrap_err().downcast_mut::<String>().unwrap(),
+    );
+    assert_eq!(
+        "oh no!",
+        bail_error()
+            .unwrap_err()
+            .downcast_mut::<io::Error>()
+            .unwrap()
+            .to_string(),
+    );
+
+    let mut bailed = bail_fmt().unwrap_err();
+    *bailed.downcast_mut::<String>().unwrap() = "clobber".to_string();
+    assert_eq!(bailed.downcast_ref::<String>().unwrap(), "clobber");
+    assert_eq!(bailed.downcast_mut::<String>().unwrap(), "clobber");
+    assert_eq!(bailed.downcast::<String>().unwrap(), "clobber");
+}
+
+#[test]
+fn test_drop() {
+    let has_dropped = Flag::new();
+    let error = Error::new(DetectDrop::new(&has_dropped));
+    drop(error.downcast::<DetectDrop>().unwrap());
+    assert!(has_dropped.get());
+}
+
+#[test]
+fn test_as_ref() {
+    let error = bail_error().unwrap_err();
+    let ref_dyn: &dyn StdError = error.as_ref();
+    assert_eq!("oh no!", ref_dyn.to_string());
+    let ref_dyn_send_sync: &(dyn StdError + Send + Sync) = error.as_ref();
+    assert_eq!("oh no!", ref_dyn_send_sync.to_string());
+}
+
+#[test]
+fn test_large_alignment() {
+    #[repr(align(64))]
+    #[derive(Debug)]
+    struct LargeAlignedError(&'static str);
+
+    impl Display for LargeAlignedError {
+        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+            f.write_str(self.0)
+        }
+    }
+
+    impl StdError for LargeAlignedError {}
+
+    let error = Error::new(LargeAlignedError("oh no!"));
+    assert_eq!(
+        "oh no!",
+        error.downcast_ref::<LargeAlignedError>().unwrap().0
+    );
+}
+
+#[test]
+fn test_unsuccessful_downcast() {
+    let mut error = bail_error().unwrap_err();
+    assert!(error.downcast_ref::<&str>().is_none());
+    assert!(error.downcast_mut::<&str>().is_none());
+    assert!(error.downcast::<&str>().is_err());
+}