1 files changed, 53 insertions, 0 deletions
diff --git a/library/std/src/io/error/tests.rs b/library/std/src/io/error/tests.rs
new file mode 100644
index 00000000000..0cce9368c80
--- /dev/null
+++ b/library/std/src/io/error/tests.rs
@@ -0,0 +1,53 @@
+use super::{Custom, Error, ErrorKind, Repr};
+use crate::error;
+use crate::fmt;
+use crate::sys::decode_error_kind;
+use crate::sys::os::error_string;
+
+#[test]
+fn test_debug_error() {
+    let code = 6;
+    let msg = error_string(code);
+    let kind = decode_error_kind(code);
+    let err = Error {
+        repr: Repr::Custom(box Custom {
+            kind: ErrorKind::InvalidInput,
+            error: box Error { repr: super::Repr::Os(code) },
+        }),
+    };
+    let expected = format!(
+        "Custom {{ \
+         kind: InvalidInput, \
+         error: Os {{ \
+         code: {:?}, \
+         kind: {:?}, \
+         message: {:?} \
+         }} \
+         }}",
+        code, kind, msg
+    );
+    assert_eq!(format!("{:?}", err), expected);
+}
+
+#[test]
+fn test_downcasting() {
+    #[derive(Debug)]
+    struct TestError;
+
+    impl fmt::Display for TestError {
+        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+            f.write_str("asdf")
+        }
+    }
+
+    impl error::Error for TestError {}
+
+    // we have to call all of these UFCS style right now since method
+    // resolution won't implicitly drop the Send+Sync bounds
+    let mut err = Error::new(ErrorKind::Other, TestError);
+    assert!(err.get_ref().unwrap().is::<TestError>());
+    assert_eq!("asdf", err.get_ref().unwrap().to_string());
+    assert!(err.get_mut().unwrap().is::<TestError>());
+    let extracted = err.into_inner().unwrap();
+    extracted.downcast::<TestError>().unwrap();
+}