vcf/io/writer/record/info/field/value: Add character writer

noodles-vcf/src/io/writer/record/info/field/value.rs

@@ -1,9 +1,10 @@
 mod array;
+mod character;
 mod string;
 
 use std::io::{self, Write};
 
-use self::{array::write_array, string::write_string};
+use self::{array::write_array, character::write_character, string::write_string};
 use crate::variant::record::info::field::Value;
 
 pub(super) fn write_value<W>(writer: &mut W, value: &Value) -> io::Result<()>
@@ -14,7 +15,7 @@ where
         Value::Integer(n) => write!(writer, "{n}"),
         Value::Float(n) => write!(writer, "{n}"),
         Value::Flag => Ok(()),
-        Value::Character(c) => write!(writer, "{c}"),
+        Value::Character(c) => write_character(writer, *c),
         Value::String(s) => write_string(writer, s),
         Value::Array(array) => write_array(writer, array),
     }

noodles-vcf/src/io/writer/record/info/field/value/character.rs

@@ -0,0 +1,28 @@
+use std::io::{self, Write};
+
+pub(super) fn write_character<W>(writer: &mut W, c: char) -> io::Result<()>
+where
+    W: Write,
+{
+    write!(writer, "{c}")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_write_character() -> io::Result<()> {
+        let mut buf = Vec::new();
+
+        buf.clear();
+        write_character(&mut buf, 'n')?;
+        assert_eq!(buf, b"n");
+
+        buf.clear();
+        write_character(&mut buf, ':')?;
+        assert_eq!(buf, b":"); // FIXME
+
+        Ok(())
+    }
+}