vcf/io/writer/record: Add reference bases writer

noodles-vcf/src/io/writer/record.rs

@@ -4,6 +4,7 @@ mod ids;
 mod info;
 mod position;
 mod quality_score;
+mod reference_bases;
 mod reference_sequence_name;
 mod samples;
 
@@ -12,7 +13,8 @@ use std::io::{self, Write};
 use self::{
     alternate_bases::write_alternate_bases, filters::write_filters, ids::write_ids,
     info::write_info, position::write_position, quality_score::write_quality_score,
-    reference_sequence_name::write_reference_sequence_name, samples::write_samples,
+    reference_bases::write_reference_bases, reference_sequence_name::write_reference_sequence_name,
+    samples::write_samples,
 };
 use crate::{variant::Record, Header};
 
@@ -36,11 +38,7 @@ where
     write_ids(writer, record.ids())?;
 
     writer.write_all(DELIMITER)?;
-
-    for result in record.reference_bases().iter() {
-        let base = result?;
-        writer.write_all(&[base])?;
-    }
+    write_reference_bases(writer, record.reference_bases())?;
 
     writer.write_all(DELIMITER)?;
     write_alternate_bases(writer, record.alternate_bases())?;

noodles-vcf/src/io/writer/record/reference_bases.rs

@@ -0,0 +1,36 @@
+use std::io::{self, Write};
+
+use crate::variant::record::ReferenceBases;
+
+pub(super) fn write_reference_bases<W, B>(writer: &mut W, reference_bases: B) -> io::Result<()>
+where
+    W: Write,
+    B: ReferenceBases,
+{
+    for result in reference_bases.iter() {
+        let base = result?;
+        writer.write_all(&[base])?;
+    }
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_write_reference_bases() -> io::Result<()> {
+        let mut buf = Vec::new();
+
+        buf.clear();
+        write_reference_bases(&mut buf, "A")?;
+        assert_eq!(buf, b"A");
+
+        buf.clear();
+        write_reference_bases(&mut buf, "AC")?;
+        assert_eq!(buf, b"AC");
+
+        Ok(())
+    }
+}