sam/writer/record/cigar: Extract kind writer

noodles-sam/src/writer/record/cigar.rs

@@ -17,28 +17,33 @@ where
     } else {
         for result in cigar.iter() {
             let op = result?;
-
             num::write_usize(writer, op.len())?;
-
-            let c = match op.kind() {
-                Kind::Match => b'M',
-                Kind::Insertion => b'I',
-                Kind::Deletion => b'D',
-                Kind::Skip => b'N',
-                Kind::SoftClip => b'S',
-                Kind::HardClip => b'H',
-                Kind::Pad => b'P',
-                Kind::SequenceMatch => b'=',
-                Kind::SequenceMismatch => b'X',
-            };
-
-            writer.write_all(&[c])?;
+            write_kind(writer, op.kind())?;
         }
     }
 
     Ok(())
 }
 
+fn write_kind<W>(writer: &mut W, kind: Kind) -> io::Result<()>
+where
+    W: Write,
+{
+    let c = match kind {
+        Kind::Match => b'M',
+        Kind::Insertion => b'I',
+        Kind::Deletion => b'D',
+        Kind::Skip => b'N',
+        Kind::SoftClip => b'S',
+        Kind::HardClip => b'H',
+        Kind::Pad => b'P',
+        Kind::SequenceMatch => b'=',
+        Kind::SequenceMismatch => b'X',
+    };
+
+    writer.write_all(&[c])
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -59,4 +64,28 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    fn test_write_kind() -> io::Result<()> {
+        fn t(buf: &mut Vec<u8>, kind: Kind, expected: &[u8]) -> io::Result<()> {
+            buf.clear();
+            write_kind(buf, kind)?;
+            assert_eq!(buf, expected);
+            Ok(())
+        }
+
+        let mut buf = Vec::new();
+
+        t(&mut buf, Kind::Match, b"M")?;
+        t(&mut buf, Kind::Insertion, b"I")?;
+        t(&mut buf, Kind::Deletion, b"D")?;
+        t(&mut buf, Kind::Skip, b"N")?;
+        t(&mut buf, Kind::SoftClip, b"S")?;
+        t(&mut buf, Kind::HardClip, b"H")?;
+        t(&mut buf, Kind::Pad, b"P")?;
+        t(&mut buf, Kind::SequenceMatch, b"=")?;
+        t(&mut buf, Kind::SequenceMismatch, b"X")?;
+
+        Ok(())
+    }
 }