refactor path fn to be cleaner and more readable (#1195)

core/src/core/pmmr.rs

@@ -838,14 +838,11 @@ pub fn is_left_sibling(pos: u64) -> bool {
 /// The size (and therefore the set of peaks) of the MMR
 /// is defined by last_pos.
 pub fn path(pos: u64, last_pos: u64) -> Vec<u64> {
-	let mut path = vec![pos];
+	let mut path = vec![];
 	let mut current = pos;
-	while current + 1 <= last_pos {
+	while current <= last_pos {
+		path.push(current);
 		let (parent, _) = family(current);
-		if parent > last_pos {
-			break;
-		}
-		path.push(parent);
 		current = parent;
 	}
 	path

core/tests/pmmr.rs

@@ -93,18 +93,18 @@ where
 
 	fn rewind(
 		&mut self,
-		position: u64,
-		rewind_add_pos: &Bitmap,
-		rewind_rm_pos: &Bitmap,
+		_position: u64,
+		_rewind_add_pos: &Bitmap,
+		_rewind_rm_pos: &Bitmap,
 	) -> Result<(), String> {
-		panic!("not yet implemented for vec backend...");
+		panic!("not implemented for vec backend...");
 	}
 
 	fn get_data_file_path(&self) -> String {
 		"".to_string()
 	}
 
-	fn snapshot(&self, header: &BlockHeader) -> Result<(), String> {
+	fn snapshot(&self, _header: &BlockHeader) -> Result<(), String> {
 		Ok(())
 	}
 
@@ -208,6 +208,14 @@ fn various_families() {
 	assert_eq!(pmmr::family(1_000), (1_001, 997));
 }
 
+#[test]
+fn test_paths() {
+	assert_eq!(pmmr::path(1, 1), [1]);
+	assert_eq!(pmmr::path(1, 3), [1, 3]);
+	assert_eq!(pmmr::path(2, 3), [2, 3]);
+	assert_eq!(pmmr::path(4, 16), [4, 6, 7, 15]);
+}
+
 #[test]
 fn test_is_left_sibling() {
 	assert_eq!(pmmr::is_left_sibling(1), true);