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

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

@@ -1,8 +1,9 @@
 mod position;
+mod score;
 
 use std::io::{self, Write};
 
-use self::position::write_position;
+use self::{position::write_position, score::write_score};
 use crate::RecordBuf;
 
 pub(crate) fn write_record<W>(writer: &mut W, record: &RecordBuf) -> io::Result<()>
@@ -24,12 +25,7 @@ where
     write_position(writer, record.end())?;
     write_separator(writer)?;
 
-    if let Some(score) = record.score() {
-        write!(writer, "{score}")?;
-    } else {
-        write_missing(writer)?;
-    }
-
+    write_score(writer, record.score())?;
     write_separator(writer)?;
 
     write!(writer, "{}", record.strand())?;

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

@@ -0,0 +1,34 @@
+use std::io::{self, Write};
+
+use super::write_missing;
+
+pub(super) fn write_score<W>(writer: &mut W, score: Option<f32>) -> io::Result<()>
+where
+    W: Write,
+{
+    if let Some(n) = score {
+        write!(writer, "{n}")
+    } else {
+        write_missing(writer)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_write_score() -> io::Result<()> {
+        let mut buf = Vec::new();
+
+        buf.clear();
+        write_score(&mut buf, None)?;
+        assert_eq!(buf, b".");
+
+        buf.clear();
+        write_score(&mut buf, Some(0.0))?;
+        assert_eq!(buf, b"0");
+
+        Ok(())
+    }
+}