1 files changed, 69 insertions, 0 deletions
diff --git a/third_party/rust/anyhow/tests/test_chain.rs b/third_party/rust/anyhow/tests/test_chain.rs
new file mode 100644
index 0000000000..c8b901ab41
--- /dev/null
+++ b/third_party/rust/anyhow/tests/test_chain.rs
@@ -0,0 +1,69 @@
+use anyhow::{anyhow, Chain, Error};
+
+fn error() -> Error {
+    anyhow!({ 0 }).context(1).context(2).context(3)
+}
+
+#[test]
+fn test_iter() {
+    let e = error();
+    let mut chain = e.chain();
+    assert_eq!("3", chain.next().unwrap().to_string());
+    assert_eq!("2", chain.next().unwrap().to_string());
+    assert_eq!("1", chain.next().unwrap().to_string());
+    assert_eq!("0", chain.next().unwrap().to_string());
+    assert!(chain.next().is_none());
+    assert!(chain.next_back().is_none());
+}
+
+#[test]
+fn test_rev() {
+    let e = error();
+    let mut chain = e.chain().rev();
+    assert_eq!("0", chain.next().unwrap().to_string());
+    assert_eq!("1", chain.next().unwrap().to_string());
+    assert_eq!("2", chain.next().unwrap().to_string());
+    assert_eq!("3", chain.next().unwrap().to_string());
+    assert!(chain.next().is_none());
+    assert!(chain.next_back().is_none());
+}
+
+#[test]
+fn test_len() {
+    let e = error();
+    let mut chain = e.chain();
+    assert_eq!(4, chain.len());
+    assert_eq!((4, Some(4)), chain.size_hint());
+    assert_eq!("3", chain.next().unwrap().to_string());
+    assert_eq!(3, chain.len());
+    assert_eq!((3, Some(3)), chain.size_hint());
+    assert_eq!("0", chain.next_back().unwrap().to_string());
+    assert_eq!(2, chain.len());
+    assert_eq!((2, Some(2)), chain.size_hint());
+    assert_eq!("2", chain.next().unwrap().to_string());
+    assert_eq!(1, chain.len());
+    assert_eq!((1, Some(1)), chain.size_hint());
+    assert_eq!("1", chain.next_back().unwrap().to_string());
+    assert_eq!(0, chain.len());
+    assert_eq!((0, Some(0)), chain.size_hint());
+    assert!(chain.next().is_none());
+}
+
+#[test]
+fn test_default() {
+    let mut c = Chain::default();
+    assert!(c.next().is_none());
+}
+
+#[test]
+#[allow(clippy::redundant_clone)]
+fn test_clone() {
+    let e = error();
+    let mut chain = e.chain().clone();
+    assert_eq!("3", chain.next().unwrap().to_string());
+    assert_eq!("2", chain.next().unwrap().to_string());
+    assert_eq!("1", chain.next().unwrap().to_string());
+    assert_eq!("0", chain.next().unwrap().to_string());
+    assert!(chain.next().is_none());
+    assert!(chain.next_back().is_none());
+}