Directory Restructure (#1163)

* Move tests -> testing

* Directory restructure

* Update Cargo.toml during restructure

* Update Makefile during restructure

* Fix arbitrary path

consensus/serde_hex/src/lib.rs

@@ -0,0 +1,69 @@
+use serde::de::{self, Visitor};
+use std::fmt;
+
+pub fn encode<T: AsRef<[u8]>>(data: T) -> String {
+    let hex = hex::encode(data);
+    let mut s = "0x".to_string();
+    s.push_str(hex.as_str());
+    s
+}
+
+pub struct PrefixedHexVisitor;
+
+impl<'de> Visitor<'de> for PrefixedHexVisitor {
+    type Value = Vec<u8>;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("a hex string with 0x prefix")
+    }
+
+    fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
+    where
+        E: de::Error,
+    {
+        if value.starts_with("0x") {
+            Ok(hex::decode(&value[2..])
+                .map_err(|e| de::Error::custom(format!("invalid hex ({:?})", e)))?)
+        } else {
+            Err(de::Error::custom("missing 0x prefix"))
+        }
+    }
+}
+
+pub struct HexVisitor;
+
+impl<'de> Visitor<'de> for HexVisitor {
+    type Value = Vec<u8>;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("a hex string (irrelevant of prefix)")
+    }
+
+    fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
+    where
+        E: de::Error,
+    {
+        Ok(hex::decode(value.trim_start_matches("0x"))
+            .map_err(|e| de::Error::custom(format!("invalid hex ({:?})", e)))?)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn encoding() {
+        let bytes = vec![0, 255];
+        let hex = encode(&bytes);
+        assert_eq!(hex.as_str(), "0x00ff");
+
+        let bytes = vec![];
+        let hex = encode(&bytes);
+        assert_eq!(hex.as_str(), "0x");
+
+        let bytes = vec![1, 2, 3];
+        let hex = encode(&bytes);
+        assert_eq!(hex.as_str(), "0x010203");
+    }
+}