From a322a530fb4acc72bbe699e2314b2c7c094cff4e Mon Sep 17 00:00:00 2001
From: Boog900 <108027008+Boog900@users.noreply.github.com>
Date: Thu, 5 Oct 2023 11:52:42 +0000
Subject: [PATCH] Fix empty seq (#58)

* fix serialization of empty sequences.

* add a test for empty sequences.

* update changelog + fmt
---
 CHANGELOG.md   |  1 +
 src/ser.rs     |  9 ++++++---
 tests/other.rs | 14 ++++++++++++++
 3 files changed, 21 insertions(+), 3 deletions(-)
 create mode 100644 tests/other.rs

diff --git a/CHANGELOG.md b/CHANGELOG.md
index dd210bb..ba77dbb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- Fixed serialization of empty sequences ([#58](https://github.com/monero-rs/monero-epee-bin-serde/pull/58))
 - No longer panic on unknown fields ([#46](https://github.com/monero-rs/monero-epee-bin-serde/pull/46))
 - Deserialization of nested structs ([#37](https://github.com/monero-rs/monero-epee-bin-serde/pull/37)).
 
diff --git a/src/ser.rs b/src/ser.rs
index e1c94c1..26e409e 100644
--- a/src/ser.rs
+++ b/src/ser.rs
@@ -216,9 +216,12 @@ impl<'a, 'b> serde::Serializer for &'a mut Serializer<'b> {
     }
 
     fn serialize_seq(self, len: Option<usize>) -> Result<Self::SerializeSeq> {
-        self.state = State::First {
-            length: len.ok_or_else(Error::no_length)?,
-        };
+        let len = len.ok_or_else(Error::no_length)?;
+        self.state = State::First { length: len };
+
+        if len == 0 {
+            self.write_marker(Marker::Sequence { element: 255 })?;
+        }
 
         Ok(self)
     }
diff --git a/tests/other.rs b/tests/other.rs
new file mode 100644
index 0000000..2a0862f
--- /dev/null
+++ b/tests/other.rs
@@ -0,0 +1,14 @@
+use monero_epee_bin_serde::{from_bytes, to_bytes};
+use serde::{Deserialize, Serialize};
+
+#[derive(Default, Deserialize, Serialize, PartialEq, Debug)]
+struct TestStruct {
+    seq: Vec<u32>,
+}
+
+#[test]
+fn empty_sequence() {
+    let obj = TestStruct::default();
+    let data = to_bytes(&obj).unwrap();
+    assert_eq!(obj, from_bytes(data).unwrap());
+}