gff/io/writer/line/record: Add position writer

noodles-gff/src/io/writer/line/record.rs

@@ -1,5 +1,8 @@
+mod position;
+
 use std::io::{self, Write};
 
+use self::position::write_position;
 use crate::RecordBuf;
 
 pub(crate) fn write_record<W>(writer: &mut W, record: &RecordBuf) -> io::Result<()>
@@ -15,10 +18,10 @@ where
     writer.write_all(record.ty().as_bytes())?;
     write_separator(writer)?;
 
-    write!(writer, "{}", record.start())?;
+    write_position(writer, record.start())?;
     write_separator(writer)?;
 
-    write!(writer, "{}", record.end())?;
+    write_position(writer, record.end())?;
     write_separator(writer)?;
 
     if let Some(score) = record.score() {

noodles-gff/src/io/writer/line/record/position.rs

@@ -0,0 +1,23 @@
+use std::io::{self, Write};
+
+use noodles_core::Position;
+
+pub(super) fn write_position<W>(writer: &mut W, position: Position) -> io::Result<()>
+where
+    W: Write,
+{
+    write!(writer, "{}", position)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_write_position() -> io::Result<()> {
+        let mut buf = Vec::new();
+        write_position(&mut buf, Position::MIN)?;
+        assert_eq!(buf, b"1");
+        Ok(())
+    }
+}