From 5bd0c85ce0809593ea123a0af3139d41033176d5 Mon Sep 17 00:00:00 2001
From: Emanuel Pilz <emonadeo@gmail.com>
Date: Tue, 22 Oct 2024 15:00:23 +0200
Subject: [PATCH] feat: `Value` representation of `Simple` values

Co-authored-by: Hendrik Wolff <hendrik.wolff@agdsn.me>
Co-authored-by: Theodor Straube <theo.straube@googlemail.com>
Co-authored-by: moehr1z <mooehr1z@gmail.com>
Signed-off-by: Emanuel Pilz <emonadeo@gmail.com>
---
 ciborium/src/de/mod.rs          |  21 +-
 ciborium/src/lib.rs             |   1 +
 ciborium/src/ser/mod.rs         |  10 +-
 ciborium/src/simple.rs          | 403 ++++++++++++++++++++++++++++++++
 ciborium/src/value/canonical.rs |   1 +
 ciborium/src/value/de.rs        |  37 ++-
 ciborium/src/value/mod.rs       |  19 +-
 ciborium/src/value/ser.rs       |  17 +-
 ciborium/tests/macro.rs         |  96 ++++----
 ciborium/tests/simple.rs        |  58 +++++
 ciborium/tests/value.rs         |  80 +++++++
 11 files changed, 667 insertions(+), 76 deletions(-)
 create mode 100644 ciborium/src/simple.rs
 create mode 100644 ciborium/tests/simple.rs
 create mode 100644 ciborium/tests/value.rs

diff --git a/ciborium/src/de/mod.rs b/ciborium/src/de/mod.rs
index 18742e4..680a04e 100644
--- a/ciborium/src/de/mod.rs
+++ b/ciborium/src/de/mod.rs
@@ -213,8 +213,11 @@ where
             Header::Simple(simple::FALSE) => self.deserialize_bool(visitor),
             Header::Simple(simple::TRUE) => self.deserialize_bool(visitor),
             Header::Simple(simple::NULL) => self.deserialize_option(visitor),
-            Header::Simple(simple::UNDEFINED) => self.deserialize_option(visitor),
-            h @ Header::Simple(..) => Err(h.expected("known simple value")),
+            Header::Simple(_) => self.recurse(|me| {
+                let mut simple_de =
+                    crate::simple::SimpleDeserializer::<_, Self>::new(&mut me.decoder);
+                visitor.visit_newtype_struct(&mut simple_de)
+            }),
 
             h @ Header::Break => Err(h.expected("non-break")),
         }
@@ -222,16 +225,10 @@ where
 
     #[inline]
     fn deserialize_bool<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value, Self::Error> {
-        loop {
-            let offset = self.decoder.offset();
-
-            return match self.decoder.pull()? {
-                Header::Tag(..) => continue,
-                Header::Simple(simple::FALSE) => visitor.visit_bool(false),
-                Header::Simple(simple::TRUE) => visitor.visit_bool(true),
-                _ => Err(Error::semantic(offset, "expected bool")),
-            };
-        }
+        self.recurse(|me| {
+            let mut simple_de = crate::simple::SimpleDeserializer::<_, Self>::new(&mut me.decoder);
+            simple_de.deserialize_bool(visitor)
+        })
     }
 
     #[inline]
diff --git a/ciborium/src/lib.rs b/ciborium/src/lib.rs
index f143943..ed5ca47 100644
--- a/ciborium/src/lib.rs
+++ b/ciborium/src/lib.rs
@@ -94,6 +94,7 @@ extern crate alloc;
 
 pub mod de;
 pub mod ser;
+pub mod simple;
 pub mod tag;
 pub mod value;
 
diff --git a/ciborium/src/ser/mod.rs b/ciborium/src/ser/mod.rs
index 03dd1da..eeeb1fe 100644
--- a/ciborium/src/ser/mod.rs
+++ b/ciborium/src/ser/mod.rs
@@ -200,10 +200,16 @@ where
     #[inline]
     fn serialize_newtype_struct<U: ?Sized + ser::Serialize>(
         self,
-        _name: &'static str,
+        name: &'static str,
         value: &U,
     ) -> Result<(), Self::Error> {
-        value.serialize(self)
+        match name {
+            "@@SIMPLE@@" => match value.serialize(crate::simple::Serializer) {
+                Ok(x) => Ok(self.0.push(Header::Simple(x))?),
+                _ => Err(Error::Value("expected simple value".into())),
+            },
+            _ => value.serialize(self),
+        }
     }
 
     #[inline]
diff --git a/ciborium/src/simple.rs b/ciborium/src/simple.rs
new file mode 100644
index 0000000..4abafc4
--- /dev/null
+++ b/ciborium/src/simple.rs
@@ -0,0 +1,403 @@
+//! Contains helper types for dealing with CBOR simple values
+
+use ciborium_ll::{simple, Decoder, Header};
+use serde::{de, forward_to_deserialize_any, ser};
+
+pub(crate) struct SimpleDeserializer<'d, R, D> {
+    parent: core::marker::PhantomData<D>,
+    decoder: &'d mut Decoder<R>,
+}
+
+impl<'d, R, D> SimpleDeserializer<'d, R, D> {
+    pub fn new(decoder: &'d mut Decoder<R>) -> Self {
+        Self {
+            parent: core::marker::PhantomData,
+            decoder,
+        }
+    }
+}
+
+impl<'de, 'd, D: de::Deserializer<'de>, R: ciborium_io::Read> de::Deserializer<'de>
+    for &mut SimpleDeserializer<'d, R, D>
+where
+    R::Error: core::fmt::Debug,
+{
+    type Error = crate::de::Error<R::Error>;
+
+    #[inline]
+    fn deserialize_any<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value, Self::Error> {
+        let offset = self.decoder.offset();
+
+        let Header::Simple(simple) = self.decoder.pull()? else {
+                return Err(crate::de::Error::semantic(offset, "expected simple"));
+            };
+        visitor.visit_u8(simple)
+    }
+
+    #[inline]
+    fn deserialize_bool<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value, Self::Error> {
+        loop {
+            let offset = self.decoder.offset();
+
+            return match self.decoder.pull()? {
+                Header::Tag(..) => continue,
+                Header::Simple(simple::FALSE) => visitor.visit_bool(false),
+                Header::Simple(simple::TRUE) => visitor.visit_bool(true),
+                _ => Err(crate::de::Error::semantic(offset, "expected bool")),
+            };
+        }
+    }
+
+    forward_to_deserialize_any! {
+        i8 i16 i32 i64 i128
+        u8 u16 u32 u64 u128
+        f32 f64
+        char str string
+        bytes byte_buf
+        seq map
+        struct tuple tuple_struct
+        identifier ignored_any
+        option unit unit_struct newtype_struct enum
+    }
+}
+
+#[derive(Debug)]
+pub(crate) struct Error;
+
+impl core::fmt::Display for Error {
+    #[inline]
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        write!(f, "{:?}", self)
+    }
+}
+
+impl ser::StdError for Error {}
+
+impl ser::Error for Error {
+    fn custom<U: core::fmt::Display>(_msg: U) -> Self {
+        Error
+    }
+}
+
+pub(crate) struct Serializer;
+
+impl ser::Serializer for Serializer {
+    type Ok = u8;
+    type Error = Error;
+
+    type SerializeSeq = Self;
+    type SerializeTuple = Self;
+    type SerializeTupleStruct = Self;
+    type SerializeTupleVariant = Self;
+    type SerializeMap = Self;
+    type SerializeStruct = Self;
+    type SerializeStructVariant = Self;
+
+    #[inline]
+    fn serialize_bool(self, _: bool) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_i8(self, _: i8) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_i16(self, _: i16) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_i32(self, _: i32) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_i64(self, _: i64) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_i128(self, _: i128) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_u8(self, v: u8) -> Result<u8, Self::Error> {
+        Ok(v)
+    }
+
+    #[inline]
+    fn serialize_u16(self, _: u16) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_u32(self, _: u32) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_u64(self, _: u64) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_u128(self, _: u128) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_f32(self, _: f32) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_f64(self, _: f64) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_char(self, _: char) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_str(self, _: &str) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_bytes(self, _: &[u8]) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_none(self) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_some<U: ?Sized + ser::Serialize>(self, _: &U) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_unit(self) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_unit_struct(self, _name: &'static str) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_unit_variant(
+        self,
+        _name: &'static str,
+        _index: u32,
+        _variant: &'static str,
+    ) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_newtype_struct<U: ?Sized + ser::Serialize>(
+        self,
+        _name: &'static str,
+        _value: &U,
+    ) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_newtype_variant<U: ?Sized + ser::Serialize>(
+        self,
+        _name: &'static str,
+        _index: u32,
+        _variant: &'static str,
+        _value: &U,
+    ) -> Result<u8, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_seq(self, _length: Option<usize>) -> Result<Self::SerializeSeq, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_tuple(self, _length: usize) -> Result<Self::SerializeTuple, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_tuple_struct(
+        self,
+        _name: &'static str,
+        _length: usize,
+    ) -> Result<Self::SerializeTupleStruct, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_tuple_variant(
+        self,
+        _name: &'static str,
+        _index: u32,
+        _variant: &'static str,
+        _length: usize,
+    ) -> Result<Self::SerializeTupleVariant, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_map(self, _length: Option<usize>) -> Result<Self::SerializeMap, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_struct(
+        self,
+        _name: &'static str,
+        _length: usize,
+    ) -> Result<Self::SerializeStruct, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_struct_variant(
+        self,
+        _name: &'static str,
+        _index: u32,
+        _variant: &'static str,
+        _length: usize,
+    ) -> Result<Self::SerializeStructVariant, Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn is_human_readable(&self) -> bool {
+        false
+    }
+}
+
+impl ser::SerializeSeq for Serializer {
+    type Ok = u8;
+    type Error = Error;
+
+    #[inline]
+    fn serialize_element<U: ?Sized + ser::Serialize>(&mut self, _value: &U) -> Result<(), Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn end(self) -> Result<Self::Ok, Self::Error> {
+        Err(Error)
+    }
+}
+
+impl ser::SerializeTuple for Serializer {
+    type Ok = u8;
+    type Error = Error;
+
+    #[inline]
+    fn serialize_element<U: ?Sized + ser::Serialize>(&mut self, _value: &U) -> Result<(), Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn end(self) -> Result<Self::Ok, Self::Error> {
+        Err(Error)
+    }
+}
+
+impl ser::SerializeTupleStruct for Serializer {
+    type Ok = u8;
+    type Error = Error;
+
+    #[inline]
+    fn serialize_field<U: ?Sized + ser::Serialize>(&mut self, _value: &U) -> Result<(), Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn end(self) -> Result<Self::Ok, Self::Error> {
+        Err(Error)
+    }
+}
+
+impl ser::SerializeTupleVariant for Serializer {
+    type Ok = u8;
+    type Error = Error;
+
+    #[inline]
+    fn serialize_field<U: ?Sized + ser::Serialize>(&mut self, _value: &U) -> Result<(), Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn end(self) -> Result<Self::Ok, Self::Error> {
+        Err(Error)
+    }
+}
+
+impl ser::SerializeMap for Serializer {
+    type Ok = u8;
+    type Error = Error;
+
+    #[inline]
+    fn serialize_key<U: ?Sized + ser::Serialize>(&mut self, _key: &U) -> Result<(), Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn serialize_value<U: ?Sized + ser::Serialize>(&mut self, _value: &U) -> Result<(), Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn end(self) -> Result<Self::Ok, Self::Error> {
+        Err(Error)
+    }
+}
+
+impl ser::SerializeStruct for Serializer {
+    type Ok = u8;
+    type Error = Error;
+
+    #[inline]
+    fn serialize_field<U: ?Sized + ser::Serialize>(
+        &mut self,
+        _key: &'static str,
+        _value: &U,
+    ) -> Result<(), Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn end(self) -> Result<Self::Ok, Self::Error> {
+        Err(Error)
+    }
+}
+
+impl ser::SerializeStructVariant for Serializer {
+    type Ok = u8;
+    type Error = Error;
+
+    #[inline]
+    fn serialize_field<U: ?Sized + ser::Serialize>(
+        &mut self,
+        _key: &'static str,
+        _value: &U,
+    ) -> Result<(), Self::Error> {
+        Err(Error)
+    }
+
+    #[inline]
+    fn end(self) -> Result<Self::Ok, Self::Error> {
+        Err(Error)
+    }
+}
diff --git a/ciborium/src/value/canonical.rs b/ciborium/src/value/canonical.rs
index 072e1cf..823d96a 100644
--- a/ciborium/src/value/canonical.rs
+++ b/ciborium/src/value/canonical.rs
@@ -55,6 +55,7 @@ pub fn cmp_value(v1: &Value, v2: &Value) -> Ordering {
             },
             Some(x) => x,
         },
+        (Simple(s), Simple(o)) => s.cmp(o),
         (_, _) => serialized_canonical_cmp(v1, v2),
     }
 }
diff --git a/ciborium/src/value/de.rs b/ciborium/src/value/de.rs
index f58a017..701f6cb 100644
--- a/ciborium/src/value/de.rs
+++ b/ciborium/src/value/de.rs
@@ -7,7 +7,10 @@ use super::{Error, Integer, Value};
 use alloc::{boxed::Box, string::String, vec::Vec};
 use core::iter::Peekable;
 
-use ciborium_ll::tag;
+use ciborium_ll::{
+    simple::{FALSE, NULL, TRUE, UNDEFINED},
+    tag,
+};
 use serde::de::{self, Deserializer as _};
 
 impl<'a> From<Integer> for de::Unexpected<'a> {
@@ -28,14 +31,17 @@ impl<'a> From<&'a Value> for de::Unexpected<'a> {
     fn from(value: &'a Value) -> Self {
         match value {
             Value::Bool(x) => Self::Bool(*x),
+            Value::Simple(FALSE) => Self::Bool(false),
+            Value::Simple(TRUE) => Self::Bool(true),
             Value::Integer(x) => Self::from(*x),
             Value::Float(x) => Self::Float(*x),
             Value::Bytes(x) => Self::Bytes(x),
             Value::Text(x) => Self::Str(x),
             Value::Array(..) => Self::Seq,
             Value::Map(..) => Self::Map,
-            Value::Null => Self::Other("null"),
+            Value::Null | Value::Simple(NULL) => Self::Other("null"),
             Value::Tag(..) => Self::Other("tag"),
+            Value::Simple(_) => Self::Other("simple"),
         }
     }
 }
@@ -110,7 +116,21 @@ impl<'de> serde::de::Visitor<'de> for Visitor {
         self,
         deserializer: D,
     ) -> Result<Self::Value, D::Error> {
-        deserializer.deserialize_any(self)
+        struct Inner;
+
+        impl<'de> serde::de::Visitor<'de> for Inner {
+            type Value = Value;
+
+            fn expecting(&self, formatter: &mut core::fmt::Formatter) -> core::fmt::Result {
+                formatter.write_str("a simple value")
+            }
+
+            fn visit_u8<E>(self, v: u8) -> Result<Self::Value, E> {
+                Ok(Value::Simple(v))
+            }
+        }
+
+        deserializer.deserialize_any(Inner)
     }
 
     #[inline]
@@ -234,7 +254,9 @@ impl<'a, 'de> de::Deserializer<'de> for Deserializer<&'a Value> {
             Value::Array(x) => visitor.visit_seq(Deserializer(x.iter())),
             Value::Map(x) => visitor.visit_map(Deserializer(x.iter().peekable())),
             Value::Bool(x) => visitor.visit_bool(*x),
-            Value::Null => visitor.visit_none(),
+            Value::Simple(FALSE) => visitor.visit_bool(false),
+            Value::Simple(TRUE) => visitor.visit_bool(true),
+            Value::Null | Value::Simple(NULL | UNDEFINED) => visitor.visit_none(),
 
             Value::Tag(t, v) => {
                 let parent: Deserializer<&Value> = Deserializer(v);
@@ -253,6 +275,7 @@ impl<'a, 'de> de::Deserializer<'de> for Deserializer<&'a Value> {
             }
 
             Value::Float(x) => visitor.visit_f64(*x),
+            Value::Simple(_) => visitor.visit_newtype_struct(self),
         }
     }
 
@@ -446,7 +469,7 @@ impl<'a, 'de> de::Deserializer<'de> for Deserializer<&'a Value> {
     #[inline]
     fn deserialize_option<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value, Self::Error> {
         match self.0 {
-            Value::Null => visitor.visit_none(),
+            Value::Null | Value::Simple(NULL) => visitor.visit_none(),
             x => visitor.visit_some(Self(x)),
         }
     }
@@ -454,7 +477,7 @@ impl<'a, 'de> de::Deserializer<'de> for Deserializer<&'a Value> {
     #[inline]
     fn deserialize_unit<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value, Self::Error> {
         match self.0 {
-            Value::Null => visitor.visit_unit(),
+            Value::Null | Value::Simple(NULL) => visitor.visit_unit(),
             _ => Err(de::Error::invalid_type(self.0.into(), &"null")),
         }
     }
@@ -605,7 +628,7 @@ impl<'a, 'de> de::VariantAccess<'de> for Deserializer<&'a Value> {
     #[inline]
     fn unit_variant(self) -> Result<(), Self::Error> {
         match self.0 {
-            Value::Null => Ok(()),
+            Value::Null | Value::Simple(NULL) => Ok(()),
             _ => Err(de::Error::invalid_type(self.0.into(), &"unit")),
         }
     }
diff --git a/ciborium/src/value/mod.rs b/ciborium/src/value/mod.rs
index 7233026..8f742e9 100644
--- a/ciborium/src/value/mod.rs
+++ b/ciborium/src/value/mod.rs
@@ -10,6 +10,7 @@ mod error;
 mod ser;
 
 pub use canonical::CanonicalValue;
+use ciborium_ll::simple::{FALSE, NULL, TRUE, UNDEFINED};
 pub use error::Error;
 pub use integer::Integer;
 
@@ -45,6 +46,9 @@ pub enum Value {
 
     /// A map
     Map(Vec<(Value, Value)>),
+
+    /// A Simple Value
+    Simple(u8),
 }
 
 impl Value {
@@ -308,7 +312,9 @@ impl Value {
     /// ```
     pub fn as_bool(&self) -> Option<bool> {
         match *self {
-            Value::Bool(b) => Some(b),
+            Self::Bool(b) => Some(b),
+            Self::Simple(FALSE) => Some(false),
+            Self::Simple(TRUE) => Some(true),
             _ => None,
         }
     }
@@ -327,12 +333,14 @@ impl Value {
     /// ```
     pub fn into_bool(self) -> Result<bool, Self> {
         match self {
-            Value::Bool(b) => Ok(b),
+            Self::Bool(b) => Ok(b),
+            Self::Simple(FALSE) => Ok(false),
+            Self::Simple(TRUE) => Ok(true),
             other => Err(other),
         }
     }
 
-    /// Returns true if the `Value` is a `Null`. Returns false otherwise.
+    /// Returns true if the `Value` is a `Null` or `Undefined`. Returns false otherwise.
     ///
     /// ```
     /// # use ciborium::Value;
@@ -342,7 +350,10 @@ impl Value {
     /// assert!(value.is_null());
     /// ```
     pub fn is_null(&self) -> bool {
-        matches!(self, Value::Null)
+        matches!(
+            self,
+            Value::Null | Value::Simple(NULL) | Value::Simple(UNDEFINED)
+        )
     }
 
     /// Returns true if the `Value` is a `Tag`. Returns false otherwise.
diff --git a/ciborium/src/value/ser.rs b/ciborium/src/value/ser.rs
index 99e6587..3cfb060 100644
--- a/ciborium/src/value/ser.rs
+++ b/ciborium/src/value/ser.rs
@@ -5,6 +5,7 @@ use super::{Error, Value};
 use alloc::{vec, vec::Vec};
 
 use ::serde::ser::{self, SerializeMap as _, SerializeSeq as _, SerializeTupleVariant as _};
+use ciborium_ll::simple::{FALSE, NULL, TRUE};
 
 impl ser::Serialize for Value {
     #[inline]
@@ -12,8 +13,10 @@ impl ser::Serialize for Value {
         match self {
             Value::Bytes(x) => serializer.serialize_bytes(x),
             Value::Bool(x) => serializer.serialize_bool(*x),
+            Value::Simple(FALSE) => serializer.serialize_bool(false),
+            Value::Simple(TRUE) => serializer.serialize_bool(true),
             Value::Text(x) => serializer.serialize_str(x),
-            Value::Null => serializer.serialize_unit(),
+            Value::Null | Value::Simple(NULL) => serializer.serialize_unit(),
 
             Value::Tag(t, v) => {
                 let mut acc = serializer.serialize_tuple_variant("@@TAG@@", 0, "@@TAGGED@@", 2)?;
@@ -74,6 +77,8 @@ impl ser::Serialize for Value {
 
                 map.end()
             }
+
+            Value::Simple(x) => serializer.serialize_newtype_struct("@@SIMPLE@@", x),
         }
     }
 }
@@ -174,10 +179,16 @@ impl ser::Serializer for Serializer<()> {
     #[inline]
     fn serialize_newtype_struct<U: ?Sized + ser::Serialize>(
         self,
-        _name: &'static str,
+        name: &'static str,
         value: &U,
     ) -> Result<Value, Error> {
-        value.serialize(self)
+        match name {
+            "@@SIMPLE@@" => match value.serialize(crate::simple::Serializer) {
+                Ok(x) => Ok(Value::Simple(x)),
+                _ => Err(Error::Custom("expected simple value".into())),
+            },
+            _ => value.serialize(self),
+        }
     }
 
     #[inline]
diff --git a/ciborium/tests/macro.rs b/ciborium/tests/macro.rs
index a73fc84..dbd38bf 100644
--- a/ciborium/tests/macro.rs
+++ b/ciborium/tests/macro.rs
@@ -4,7 +4,7 @@ extern crate alloc;
 
 use ciborium::{
     cbor,
-    value::{Integer, Value, Value::Null},
+    value::{Integer, Value},
 };
 
 use rstest::rstest;
@@ -47,7 +47,7 @@ macro_rules! arr {
 
     // Simple array formulations
     case(arr![], cbor!([]).unwrap()),
-    case(arr![Null], cbor!([null]).unwrap()),
+    case(arr![Value::Null], cbor!([null]).unwrap()),
     case(arr![true], cbor!([true]).unwrap()),
     case(arr![false], cbor!([false]).unwrap()),
     case(arr!["foo"], cbor!(["foo"]).unwrap()),
@@ -61,19 +61,19 @@ macro_rules! arr {
     case(arr![map! {1=>2,3=>4}], cbor!([{1=>2,3=>4}]).unwrap()),
 
     // Two-item array formluations
-    case(arr![Null, Null], cbor!([null, null]).unwrap()),
-    case(arr![Null, true], cbor!([null, true]).unwrap()),
-    case(arr![Null, false], cbor!([null, false]).unwrap()),
-    case(arr![Null, "foo"], cbor!([null, "foo"]).unwrap()),
-    case(arr![Null, 123], cbor!([null, 123]).unwrap()),
-    case(arr![Null, -123], cbor!([null, -123]).unwrap()),
-    case(arr![Null, 1.23], cbor!([null, 1.23]).unwrap()),
-    case(arr![Null, -1.23], cbor!([null, -1.23]).unwrap()),
-    case(arr![Null, 2.5e+1], cbor!([null, 2.5e+1]).unwrap()),
-    case(arr![Null, 2.5e+1], cbor!([null, 2.5e+1]).unwrap()),
-    case(arr![Null, [1, 2]], cbor!([null, [1, 2]]).unwrap()),
-    case(arr![Null, map! {1=>2,3=>4}], cbor!([null, {1=>2,3=>4}]).unwrap()),
-    case(arr![true, Null], cbor!([true, null]).unwrap()),
+    case(arr![Value::Null, Value::Null], cbor!([null, null]).unwrap()),
+    case(arr![Value::Null, true], cbor!([null, true]).unwrap()),
+    case(arr![Value::Null, false], cbor!([null, false]).unwrap()),
+    case(arr![Value::Null, "foo"], cbor!([null, "foo"]).unwrap()),
+    case(arr![Value::Null, 123], cbor!([null, 123]).unwrap()),
+    case(arr![Value::Null, -123], cbor!([null, -123]).unwrap()),
+    case(arr![Value::Null, 1.23], cbor!([null, 1.23]).unwrap()),
+    case(arr![Value::Null, -1.23], cbor!([null, -1.23]).unwrap()),
+    case(arr![Value::Null, 2.5e+1], cbor!([null, 2.5e+1]).unwrap()),
+    case(arr![Value::Null, 2.5e+1], cbor!([null, 2.5e+1]).unwrap()),
+    case(arr![Value::Null, [1, 2]], cbor!([null, [1, 2]]).unwrap()),
+    case(arr![Value::Null, map! {1=>2,3=>4}], cbor!([null, {1=>2,3=>4}]).unwrap()),
+    case(arr![true, Value::Null], cbor!([true, null]).unwrap()),
     case(arr![true, true], cbor!([true, true]).unwrap()),
     case(arr![true, false], cbor!([true, false]).unwrap()),
     case(arr![true, "foo"], cbor!([true, "foo"]).unwrap()),
@@ -85,7 +85,7 @@ macro_rules! arr {
     case(arr![true, 2.5e+1], cbor!([true, 2.5e+1]).unwrap()),
     case(arr![true, [1, 2]], cbor!([true, [1, 2]]).unwrap()),
     case(arr![true, map! {1=>2,3=>4}], cbor!([true, {1=>2,3=>4}]).unwrap()),
-    case(arr![false, Null], cbor!([false, null]).unwrap()),
+    case(arr![false, Value::Null], cbor!([false, null]).unwrap()),
     case(arr![false, true], cbor!([false, true]).unwrap()),
     case(arr![false, false], cbor!([false, false]).unwrap()),
     case(arr![false, "foo"], cbor!([false, "foo"]).unwrap()),
@@ -97,7 +97,7 @@ macro_rules! arr {
     case(arr![false, 2.5e+1], cbor!([false, 2.5e+1]).unwrap()),
     case(arr![false, [1, 2]], cbor!([false, [1, 2]]).unwrap()),
     case(arr![false, map! {1=>2,3=>4}], cbor!([false, {1=>2,3=>4}]).unwrap()),
-    case(arr!["foo", Null], cbor!(["foo", null]).unwrap()),
+    case(arr!["foo", Value::Null], cbor!(["foo", null]).unwrap()),
     case(arr!["foo", true], cbor!(["foo", true]).unwrap()),
     case(arr!["foo", false], cbor!(["foo", false]).unwrap()),
     case(arr!["foo", "foo"], cbor!(["foo", "foo"]).unwrap()),
@@ -109,7 +109,7 @@ macro_rules! arr {
     case(arr!["foo", 2.5e+1], cbor!(["foo", 2.5e+1]).unwrap()),
     case(arr!["foo", [1, 2]], cbor!(["foo", [1, 2]]).unwrap()),
     case(arr!["foo", map! {1=>2,3=>4}], cbor!(["foo", {1=>2,3=>4}]).unwrap()),
-    case(arr![123, Null], cbor!([123, null]).unwrap()),
+    case(arr![123, Value::Null], cbor!([123, null]).unwrap()),
     case(arr![123, true], cbor!([123, true]).unwrap()),
     case(arr![123, false], cbor!([123, false]).unwrap()),
     case(arr![123, "foo"], cbor!([123, "foo"]).unwrap()),
@@ -121,7 +121,7 @@ macro_rules! arr {
     case(arr![123, 2.5e+1], cbor!([123, 2.5e+1]).unwrap()),
     case(arr![123, [1, 2]], cbor!([123, [1, 2]]).unwrap()),
     case(arr![123, map! {1=>2,3=>4}], cbor!([123, {1=>2,3=>4}]).unwrap()),
-    case(arr![-123, Null], cbor!([-123, null]).unwrap()),
+    case(arr![-123, Value::Null], cbor!([-123, null]).unwrap()),
     case(arr![-123, true], cbor!([-123, true]).unwrap()),
     case(arr![-123, false], cbor!([-123, false]).unwrap()),
     case(arr![-123, "foo"], cbor!([-123, "foo"]).unwrap()),
@@ -133,7 +133,7 @@ macro_rules! arr {
     case(arr![-123, 2.5e+1], cbor!([-123, 2.5e+1]).unwrap()),
     case(arr![-123, [1, 2]], cbor!([-123, [1, 2]]).unwrap()),
     case(arr![-123, map! {1=>2,3=>4}], cbor!([-123, {1=>2,3=>4}]).unwrap()),
-    case(arr![1.23, Null], cbor!([1.23, null]).unwrap()),
+    case(arr![1.23, Value::Null], cbor!([1.23, null]).unwrap()),
     case(arr![1.23, true], cbor!([1.23, true]).unwrap()),
     case(arr![1.23, false], cbor!([1.23, false]).unwrap()),
     case(arr![1.23, "foo"], cbor!([1.23, "foo"]).unwrap()),
@@ -145,7 +145,7 @@ macro_rules! arr {
     case(arr![1.23, 2.5e+1], cbor!([1.23, 2.5e+1]).unwrap()),
     case(arr![1.23, [1, 2]], cbor!([1.23, [1, 2]]).unwrap()),
     case(arr![1.23, map! {1=>2,3=>4}], cbor!([1.23, {1=>2,3=>4}]).unwrap()),
-    case(arr![-1.23, Null], cbor!([-1.23, null]).unwrap()),
+    case(arr![-1.23, Value::Null], cbor!([-1.23, null]).unwrap()),
     case(arr![-1.23, true], cbor!([-1.23, true]).unwrap()),
     case(arr![-1.23, false], cbor!([-1.23, false]).unwrap()),
     case(arr![-1.23, "foo"], cbor!([-1.23, "foo"]).unwrap()),
@@ -157,7 +157,7 @@ macro_rules! arr {
     case(arr![-1.23, 2.5e+1], cbor!([-1.23, 2.5e+1]).unwrap()),
     case(arr![-1.23, [1, 2]], cbor!([-1.23, [1, 2]]).unwrap()),
     case(arr![-1.23, map! {1=>2,3=>4}], cbor!([-1.23, {1=>2,3=>4}]).unwrap()),
-    case(arr![2.5e+1, Null], cbor!([2.5e+1, null]).unwrap()),
+    case(arr![2.5e+1, Value::Null], cbor!([2.5e+1, null]).unwrap()),
     case(arr![2.5e+1, true], cbor!([2.5e+1, true]).unwrap()),
     case(arr![2.5e+1, false], cbor!([2.5e+1, false]).unwrap()),
     case(arr![2.5e+1, "foo"], cbor!([2.5e+1, "foo"]).unwrap()),
@@ -169,7 +169,7 @@ macro_rules! arr {
     case(arr![2.5e+1, 2.5e+1], cbor!([2.5e+1, 2.5e+1]).unwrap()),
     case(arr![2.5e+1, [1, 2]], cbor!([2.5e+1, [1, 2]]).unwrap()),
     case(arr![2.5e+1, map! {1=>2,3=>4}], cbor!([2.5e+1, {1=>2,3=>4}]).unwrap()),
-    case(arr![2.5e+1, Null], cbor!([2.5e+1, null]).unwrap()),
+    case(arr![2.5e+1, Value::Null], cbor!([2.5e+1, null]).unwrap()),
     case(arr![2.5e+1, true], cbor!([2.5e+1, true]).unwrap()),
     case(arr![2.5e+1, false], cbor!([2.5e+1, false]).unwrap()),
     case(arr![2.5e+1, "foo"], cbor!([2.5e+1, "foo"]).unwrap()),
@@ -181,7 +181,7 @@ macro_rules! arr {
     case(arr![2.5e+1, 2.5e+1], cbor!([2.5e+1, 2.5e+1]).unwrap()),
     case(arr![2.5e+1, [1, 2]], cbor!([2.5e+1, [1, 2]]).unwrap()),
     case(arr![2.5e+1, map! {1=>2,3=>4}], cbor!([2.5e+1, {1=>2,3=>4}]).unwrap()),
-    case(arr![[1, 2], Null], cbor!([[1, 2], null]).unwrap()),
+    case(arr![[1, 2], Value::Null], cbor!([[1, 2], null]).unwrap()),
     case(arr![[1, 2], true], cbor!([[1, 2], true]).unwrap()),
     case(arr![[1, 2], false], cbor!([[1, 2], false]).unwrap()),
     case(arr![[1, 2], "foo"], cbor!([[1, 2], "foo"]).unwrap()),
@@ -193,7 +193,7 @@ macro_rules! arr {
     case(arr![[1, 2], 2.5e+1], cbor!([[1, 2], 2.5e+1]).unwrap()),
     case(arr![[1, 2], [1, 2]], cbor!([[1, 2], [1, 2]]).unwrap()),
     case(arr![[1, 2], map! {1=>2,3=>4}], cbor!([[1, 2], {1=>2,3=>4}]).unwrap()),
-    case(arr![map! {1=>2,3=>4}, Null], cbor!([{1=>2,3=>4}, null]).unwrap()),
+    case(arr![map! {1=>2,3=>4}, Value::Null], cbor!([{1=>2,3=>4}, null]).unwrap()),
     case(arr![map! {1=>2,3=>4}, true], cbor!([{1=>2,3=>4}, true]).unwrap()),
     case(arr![map! {1=>2,3=>4}, false], cbor!([{1=>2,3=>4}, false]).unwrap()),
     case(arr![map! {1=>2,3=>4}, "foo"], cbor!([{1=>2,3=>4}, "foo"]).unwrap()),
@@ -208,19 +208,19 @@ macro_rules! arr {
 
     // Map formulations
     case(map! {}, cbor!({}).unwrap()),
-    case(map! {Null => Null}, cbor!({ null => null }).unwrap()),
-    case(map! {Null => true}, cbor!({ null => true }).unwrap()),
-    case(map! {Null => false}, cbor!({ null => false }).unwrap()),
-    case(map! {Null => "foo"}, cbor!({ null => "foo" }).unwrap()),
-    case(map! {Null => 123}, cbor!({ null => 123 }).unwrap()),
-    case(map! {Null => -123}, cbor!({ null => -123 }).unwrap()),
-    case(map! {Null => 1.23}, cbor!({ null => 1.23 }).unwrap()),
-    case(map! {Null => -1.23}, cbor!({ null => -1.23 }).unwrap()),
-    case(map! {Null => 2.5e+1}, cbor!({ null => 2.5e+1 }).unwrap()),
-    case(map! {Null => 2.5e+1}, cbor!({ null => 2.5e+1 }).unwrap()),
-    case(map! {Null => [1, 2]}, cbor!({ null => [1, 2] }).unwrap()),
-    case(map! {Null => map! {1=>2,3=>4}}, cbor!({ null => {1=>2,3=>4} }).unwrap()),
-    case(map! {true => Null}, cbor!({ true => null }).unwrap()),
+    case(map! {Value::Null => Value::Null}, cbor!({ null => null }).unwrap()),
+    case(map! {Value::Null => true}, cbor!({ null => true }).unwrap()),
+    case(map! {Value::Null => false}, cbor!({ null => false }).unwrap()),
+    case(map! {Value::Null => "foo"}, cbor!({ null => "foo" }).unwrap()),
+    case(map! {Value::Null => 123}, cbor!({ null => 123 }).unwrap()),
+    case(map! {Value::Null => -123}, cbor!({ null => -123 }).unwrap()),
+    case(map! {Value::Null => 1.23}, cbor!({ null => 1.23 }).unwrap()),
+    case(map! {Value::Null => -1.23}, cbor!({ null => -1.23 }).unwrap()),
+    case(map! {Value::Null => 2.5e+1}, cbor!({ null => 2.5e+1 }).unwrap()),
+    case(map! {Value::Null => 2.5e+1}, cbor!({ null => 2.5e+1 }).unwrap()),
+    case(map! {Value::Null => [1, 2]}, cbor!({ null => [1, 2] }).unwrap()),
+    case(map! {Value::Null => map! {1=>2,3=>4}}, cbor!({ null => {1=>2,3=>4} }).unwrap()),
+    case(map! {true => Value::Null}, cbor!({ true => null }).unwrap()),
     case(map! {true => true}, cbor!({ true => true }).unwrap()),
     case(map! {true => false}, cbor!({ true => false }).unwrap()),
     case(map! {true => "foo"}, cbor!({ true => "foo" }).unwrap()),
@@ -232,7 +232,7 @@ macro_rules! arr {
     case(map! {true => 2.5e+1}, cbor!({ true => 2.5e+1 }).unwrap()),
     case(map! {true => [1, 2]}, cbor!({ true => [1, 2] }).unwrap()),
     case(map! {true => map! {1=>2,3=>4}}, cbor!({ true => {1=>2,3=>4} }).unwrap()),
-    case(map! {false => Null}, cbor!({ false => null }).unwrap()),
+    case(map! {false => Value::Null}, cbor!({ false => null }).unwrap()),
     case(map! {false => true}, cbor!({ false => true }).unwrap()),
     case(map! {false => false}, cbor!({ false => false }).unwrap()),
     case(map! {false => "foo"}, cbor!({ false => "foo" }).unwrap()),
@@ -244,7 +244,7 @@ macro_rules! arr {
     case(map! {false => 2.5e+1}, cbor!({ false => 2.5e+1 }).unwrap()),
     case(map! {false => [1, 2]}, cbor!({ false => [1, 2] }).unwrap()),
     case(map! {false => map! {1=>2,3=>4}}, cbor!({ false => {1=>2,3=>4} }).unwrap()),
-    case(map! {"foo" => Null}, cbor!({ "foo" => null }).unwrap()),
+    case(map! {"foo" => Value::Null}, cbor!({ "foo" => null }).unwrap()),
     case(map! {"foo" => true}, cbor!({ "foo" => true }).unwrap()),
     case(map! {"foo" => false}, cbor!({ "foo" => false }).unwrap()),
     case(map! {"foo" => "foo"}, cbor!({ "foo" => "foo" }).unwrap()),
@@ -256,7 +256,7 @@ macro_rules! arr {
     case(map! {"foo" => 2.5e+1}, cbor!({ "foo" => 2.5e+1 }).unwrap()),
     case(map! {"foo" => [1, 2]}, cbor!({ "foo" => [1, 2] }).unwrap()),
     case(map! {"foo" => map! {1=>2,3=>4}}, cbor!({ "foo" => {1=>2,3=>4} }).unwrap()),
-    case(map! {123 => Null}, cbor!({ 123 => null }).unwrap()),
+    case(map! {123 => Value::Null}, cbor!({ 123 => null }).unwrap()),
     case(map! {123 => true}, cbor!({ 123 => true }).unwrap()),
     case(map! {123 => false}, cbor!({ 123 => false }).unwrap()),
     case(map! {123 => "foo"}, cbor!({ 123 => "foo" }).unwrap()),
@@ -268,7 +268,7 @@ macro_rules! arr {
     case(map! {123 => 2.5e+1}, cbor!({ 123 => 2.5e+1 }).unwrap()),
     case(map! {123 => [1, 2]}, cbor!({ 123 => [1, 2] }).unwrap()),
     case(map! {123 => map! {1=>2,3=>4}}, cbor!({ 123 => {1=>2,3=>4} }).unwrap()),
-    case(map! {-123 => Null}, cbor!({ -123 => null }).unwrap()),
+    case(map! {-123 => Value::Null}, cbor!({ -123 => null }).unwrap()),
     case(map! {-123 => true}, cbor!({ -123 => true }).unwrap()),
     case(map! {-123 => false}, cbor!({ -123 => false }).unwrap()),
     case(map! {-123 => "foo"}, cbor!({ -123 => "foo" }).unwrap()),
@@ -280,7 +280,7 @@ macro_rules! arr {
     case(map! {-123 => 2.5e+1}, cbor!({ -123 => 2.5e+1 }).unwrap()),
     case(map! {-123 => [1, 2]}, cbor!({ -123 => [1, 2] }).unwrap()),
     case(map! {-123 => map! {1=>2,3=>4}}, cbor!({ -123 => {1=>2,3=>4} }).unwrap()),
-    case(map! {1.23 => Null}, cbor!({ 1.23 => null }).unwrap()),
+    case(map! {1.23 => Value::Null}, cbor!({ 1.23 => null }).unwrap()),
     case(map! {1.23 => true}, cbor!({ 1.23 => true }).unwrap()),
     case(map! {1.23 => false}, cbor!({ 1.23 => false }).unwrap()),
     case(map! {1.23 => "foo"}, cbor!({ 1.23 => "foo" }).unwrap()),
@@ -292,7 +292,7 @@ macro_rules! arr {
     case(map! {1.23 => 2.5e+1}, cbor!({ 1.23 => 2.5e+1 }).unwrap()),
     case(map! {1.23 => [1, 2]}, cbor!({ 1.23 => [1, 2] }).unwrap()),
     case(map! {1.23 => map! {1=>2,3=>4}}, cbor!({ 1.23 => {1=>2,3=>4} }).unwrap()),
-    case(map! {-1.23 => Null}, cbor!({ -1.23 => null }).unwrap()),
+    case(map! {-1.23 => Value::Null}, cbor!({ -1.23 => null }).unwrap()),
     case(map! {-1.23 => true}, cbor!({ -1.23 => true }).unwrap()),
     case(map! {-1.23 => false}, cbor!({ -1.23 => false }).unwrap()),
     case(map! {-1.23 => "foo"}, cbor!({ -1.23 => "foo" }).unwrap()),
@@ -304,7 +304,7 @@ macro_rules! arr {
     case(map! {-1.23 => 2.5e+1}, cbor!({ -1.23 => 2.5e+1 }).unwrap()),
     case(map! {-1.23 => [1, 2]}, cbor!({ -1.23 => [1, 2] }).unwrap()),
     case(map! {-1.23 => map! {1=>2,3=>4}}, cbor!({ -1.23 => {1=>2,3=>4} }).unwrap()),
-    case(map! {2.5e+1 => Null}, cbor!({ 2.5e+1 => null }).unwrap()),
+    case(map! {2.5e+1 => Value::Null}, cbor!({ 2.5e+1 => null }).unwrap()),
     case(map! {2.5e+1 => true}, cbor!({ 2.5e+1 => true }).unwrap()),
     case(map! {2.5e+1 => false}, cbor!({ 2.5e+1 => false }).unwrap()),
     case(map! {2.5e+1 => "foo"}, cbor!({ 2.5e+1 => "foo" }).unwrap()),
@@ -316,7 +316,7 @@ macro_rules! arr {
     case(map! {2.5e+1 => 2.5e+1}, cbor!({ 2.5e+1 => 2.5e+1 }).unwrap()),
     case(map! {2.5e+1 => [1, 2]}, cbor!({ 2.5e+1 => [1, 2] }).unwrap()),
     case(map! {2.5e+1 => map! {1=>2,3=>4}}, cbor!({ 2.5e+1 => {1=>2,3=>4} }).unwrap()),
-    case(map! {2.5e+1 => Null}, cbor!({ 2.5e+1 => null }).unwrap()),
+    case(map! {2.5e+1 => Value::Null}, cbor!({ 2.5e+1 => null }).unwrap()),
     case(map! {2.5e+1 => true}, cbor!({ 2.5e+1 => true }).unwrap()),
     case(map! {2.5e+1 => false}, cbor!({ 2.5e+1 => false }).unwrap()),
     case(map! {2.5e+1 => "foo"}, cbor!({ 2.5e+1 => "foo" }).unwrap()),
@@ -328,7 +328,7 @@ macro_rules! arr {
     case(map! {2.5e+1 => 2.5e+1}, cbor!({ 2.5e+1 => 2.5e+1 }).unwrap()),
     case(map! {2.5e+1 => [1, 2]}, cbor!({ 2.5e+1 => [1, 2] }).unwrap()),
     case(map! {2.5e+1 => map! {1=>2,3=>4}}, cbor!({ 2.5e+1 => {1=>2,3=>4} }).unwrap()),
-    case(map! {[1, 2] => Null}, cbor!({ [1, 2] => null }).unwrap()),
+    case(map! {[1, 2] => Value::Null}, cbor!({ [1, 2] => null }).unwrap()),
     case(map! {[1, 2] => true}, cbor!({ [1, 2] => true }).unwrap()),
     case(map! {[1, 2] => false}, cbor!({ [1, 2] => false }).unwrap()),
     case(map! {[1, 2] => "foo"}, cbor!({ [1, 2] => "foo" }).unwrap()),
@@ -340,7 +340,7 @@ macro_rules! arr {
     case(map! {[1, 2] => 2.5e+1}, cbor!({ [1, 2] => 2.5e+1 }).unwrap()),
     case(map! {[1, 2] => [1, 2]}, cbor!({ [1, 2] => [1, 2] }).unwrap()),
     case(map! {[1, 2] => map! {1=>2,3=>4}}, cbor!({ [1, 2] => {1=>2,3=>4} }).unwrap()),
-    case(map! {map! {1=>2,3=>4} => Null}, cbor!({ {1=>2,3=>4} => null }).unwrap()),
+    case(map! {map! {1=>2,3=>4} => Value::Null}, cbor!({ {1=>2,3=>4} => null }).unwrap()),
     case(map! {map! {1=>2,3=>4} => true}, cbor!({ {1=>2,3=>4} => true }).unwrap()),
     case(map! {map! {1=>2,3=>4} => false}, cbor!({ {1=>2,3=>4} => false }).unwrap()),
     case(map! {map! {1=>2,3=>4} => "foo"}, cbor!({ {1=>2,3=>4} => "foo" }).unwrap()),
diff --git a/ciborium/tests/simple.rs b/ciborium/tests/simple.rs
new file mode 100644
index 0000000..7e8f5b0
--- /dev/null
+++ b/ciborium/tests/simple.rs
@@ -0,0 +1,58 @@
+use ciborium::{from_reader, into_writer, Value};
+use ciborium_ll::simple::UNDEFINED;
+use rstest::rstest;
+use serde::{Deserialize, Serialize};
+
+#[rstest]
+#[case("e0", Value::Simple(0))]
+#[case("e1", Value::Simple(1))]
+#[case("f0", Value::Simple(16))]
+#[case("f1", Value::Simple(17))]
+#[case("f2", Value::Simple(18))]
+#[case("f3", Value::Simple(19))]
+#[case("f4", Value::Bool(false))]
+#[case("f5", Value::Bool(true))]
+#[case("f6", Value::Null)]
+#[case("f7", Value::Simple(UNDEFINED))]
+#[case("f8ff", Value::Simple(255))]
+#[case("f90000", Value::Float(0f64))]
+#[case("f93c00", Value::Float(1f64))]
+#[case("fa00000000", Value::Float(0f64))]
+#[case("fa3f800000", Value::Float(1f64))]
+fn deserialize_value(#[case] bytes: &str, #[case] expected: Value) {
+    let bytes = hex::decode(bytes).unwrap();
+    let actual: Value = from_reader(&bytes[..]).unwrap();
+    assert_eq!(actual, expected);
+}
+
+#[rstest]
+#[case(Value::Simple(0), "e0")]
+#[case(Value::Simple(1), "e1")]
+#[case(Value::Simple(16), "f0")]
+#[case(Value::Simple(17), "f1")]
+#[case(Value::Simple(18), "f2")]
+#[case(Value::Simple(19), "f3")]
+#[case(Value::Bool(false), "f4")]
+#[case(Value::Bool(true), "f5")]
+#[case(Value::Null, "f6")]
+#[case(Value::Simple(UNDEFINED), "f7")]
+#[case(Value::Simple(255), "f8ff")]
+#[case(Value::Float(0f64), "f90000")]
+#[case(Value::Float(1f64), "f93c00")]
+fn serialize_value(#[case] value: Value, #[case] bytes: &str) {
+    let expected = hex::decode(bytes).unwrap();
+    let mut actual = Vec::<u8>::new();
+    into_writer(&value, &mut actual).unwrap();
+    assert_eq!(actual, expected);
+}
+
+#[test]
+fn do_not_accept_simple_for_integer() {
+    #[derive(Debug, PartialEq, Serialize, Deserialize)]
+    pub struct NotSimple(u8);
+
+    let bytes: [u8; 1] = [0xE0];
+    let my_simple: Result<NotSimple, _> = from_reader(&bytes[..]);
+
+    assert!(my_simple.is_err());
+}
diff --git a/ciborium/tests/value.rs b/ciborium/tests/value.rs
new file mode 100644
index 0000000..d50d404
--- /dev/null
+++ b/ciborium/tests/value.rs
@@ -0,0 +1,80 @@
+use ciborium::ser::into_writer;
+use ciborium::value::Value;
+use ciborium_ll::simple::{FALSE, NULL, TRUE, UNDEFINED};
+use rstest::{fixture, rstest};
+use serde::Serialize;
+use std::collections::HashMap;
+
+#[derive(Serialize)]
+struct ExampleStruct {
+    a: Vec<String>,
+    b: f64,
+    c: HashMap<u8, Value>,
+}
+
+#[fixture]
+fn struct_instance_1() -> ExampleStruct {
+    let mut map = HashMap::new();
+    map.insert(15, Value::Bool(false));
+    ExampleStruct {
+        a: vec!["Hello".to_string(), "lol".to_string()],
+        b: 3.14,
+        c: map,
+    }
+}
+
+#[fixture]
+fn struct_instance_2() -> ExampleStruct {
+    let mut map = HashMap::new();
+    map.insert(15, Value::Bool(false));
+    ExampleStruct {
+        a: vec!["Hello".to_string()],
+        b: 4.2,
+        c: map,
+    }
+}
+
+#[rstest(
+    item,
+    bytes,
+    case(Value::Simple(0), "E0"),
+    case(Value::Simple(1), "E1"),
+    case(Value::Simple(2), "E2"),
+    case(Value::Simple(3), "E3"),
+    case(Value::Simple(4), "E4"),
+    case(Value::Simple(5), "E5"),
+    case(Value::Simple(6), "E6"),
+    case(Value::Simple(7), "E7"),
+    case(Value::Simple(8), "E8"),
+    case(Value::Simple(9), "E9"),
+    case(Value::Simple(10), "EA"),
+    case(Value::Simple(11), "EB"),
+    case(Value::Simple(12), "EC"),
+    case(Value::Simple(13), "ED"),
+    case(Value::Simple(14), "EE"),
+    case(Value::Simple(15), "EF"),
+    case(Value::Simple(16), "F0"),
+    case(Value::Simple(17), "F1"),
+    case(Value::Simple(18), "F2"),
+    case(Value::Simple(19), "F3"),
+    case(Value::Bool(false), "F4"),
+    case(Value::Simple(FALSE), "F4"),
+    case(Value::Bool(true), "F5"),
+    case(Value::Simple(TRUE), "F5"),
+    case(Value::Null, "F6"),
+    case(Value::Simple(NULL), "F6"),
+    case(Value::Simple(UNDEFINED), "F7"),
+    case(Value::Simple(32), "F820"),
+    case(Value::Simple(33), "F821"),
+    case(Value::Simple(127), "F87F"),
+    case(Value::Simple(128), "F880"),
+    case(Value::Simple(255), "F8FF")
+)]
+fn serialize(item: Value, bytes: &str) {
+    let bytes = hex::decode(bytes).unwrap();
+
+    let mut writer: Vec<u8> = Vec::new();
+    into_writer(&item, &mut writer).unwrap();
+
+    assert_eq!(writer, bytes);
+}