1 files changed, 57 insertions, 0 deletions
diff --git a/third_party/rust/ron/tests/359_deserialize_seed.rs b/third_party/rust/ron/tests/359_deserialize_seed.rs
new file mode 100644
index 0000000000..4bca6c438b
--- /dev/null
+++ b/third_party/rust/ron/tests/359_deserialize_seed.rs
@@ -0,0 +1,57 @@
+#[test]
+fn test_deserialize_seed() {
+    // Test adapted from David Tolnay's serde-yaml:
+    // https://github.com/dtolnay/serde-yaml/blob/8a806e316302fd2e6541dccee6d166dd51b689d6/tests/test_de.rs#L357-L392
+
+    struct Seed(i64);
+
+    impl<'de> serde::de::DeserializeSeed<'de> for Seed {
+        type Value = i64;
+
+        fn deserialize<D>(self, deserializer: D) -> Result<i64, D::Error>
+        where
+            D: serde::de::Deserializer<'de>,
+        {
+            struct Visitor(i64);
+
+            impl<'de> serde::de::Visitor<'de> for Visitor {
+                type Value = i64;
+
+                fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+                    write!(formatter, "an integer")
+                }
+
+                fn visit_i64<E: serde::de::Error>(self, v: i64) -> Result<i64, E> {
+                    Ok(v * self.0)
+                }
+
+                fn visit_u64<E: serde::de::Error>(self, v: u64) -> Result<i64, E> {
+                    Ok(v as i64 * self.0)
+                }
+            }
+
+            deserializer.deserialize_any(Visitor(self.0))
+        }
+    }
+
+    let cases = [("3", 5, 15), ("6", 7, 42), ("-5", 9, -45)];
+
+    for &(ron, seed, expected) in &cases {
+        let deserialized = ron::Options::default()
+            .from_str_seed(ron, Seed(seed))
+            .unwrap();
+
+        assert_eq!(expected, deserialized);
+    }
+
+    assert_eq!(
+        ron::Options::default().from_str_seed("'a'", Seed(42)),
+        Err(ron::error::SpannedError {
+            code: ron::Error::InvalidValueForType {
+                expected: String::from("an integer"),
+                found: String::from("the string \"a\""),
+            },
+            position: ron::error::Position { line: 1, col: 4 },
+        })
+    );
+}