fix(rlp): len() changes as RlpIterator is consumed

Fixes #761
paritytech · Jul 10, 2023 · 0c7806f · 0c7806f
1 parent a5ef730
commit 0c7806f
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Showing 2 changed files with 7 additions and 1 deletion.
diff --git a/rlp/src/rlpin.rs b/rlp/src/rlpin.rs
@@ -367,7 +367,7 @@ impl<'a, 'view> Iterator for RlpIterator<'a, 'view> {
 
 impl<'a, 'view> ExactSizeIterator for RlpIterator<'a, 'view> {
 	fn len(&self) -> usize {
-		self.rlp.item_count().unwrap_or(0)
+		self.rlp.item_count().unwrap_or(0).saturating_sub(self.index)
 	}
 }
 

diff --git a/rlp/tests/tests.rs b/rlp/tests/tests.rs
@@ -105,14 +105,20 @@ fn rlp_iter() {
 		let rlp = Rlp::new(&data);
 		let mut iter = rlp.iter();
 
+		assert_eq!(iter.len(), 2);
+
 		let cat = iter.next().unwrap();
 		assert!(cat.is_data());
 		assert_eq!(cat.as_raw(), &[0x83, b'c', b'a', b't']);
 
+		assert_eq!(iter.len(), 1);
+
 		let dog = iter.next().unwrap();
 		assert!(dog.is_data());
 		assert_eq!(dog.as_raw(), &[0x83, b'd', b'o', b'g']);
 
+		assert_eq!(iter.len(), 0);
+
 		let none = iter.next();
 		assert!(none.is_none());