Add proptests for sled conversions (#1253)

* Add proptests for sled conversions
* document primary helper functions

zebra-state/src/sled_state/sled_format.rs

@@ -9,6 +9,7 @@ use zebra_chain::{
     sprout, transaction, transparent,
 };
 
+#[derive(Debug, Clone, Copy, PartialEq)]
 pub struct TransactionLocation {
     pub height: block::Height,
     pub index: u32,
@@ -123,6 +124,13 @@ impl IntoSled for block::Hash {
     }
 }
 
+impl FromSled for block::Hash {
+    fn from_ivec(bytes: sled::IVec) -> Self {
+        let array = bytes.as_ref().try_into().unwrap();
+        Self(array)
+    }
+}
+
 impl IntoSled for &sprout::Nullifier {
     type Bytes = [u8; 32];
 
@@ -159,13 +167,6 @@ impl IntoSled for () {
     }
 }
 
-impl FromSled for block::Hash {
-    fn from_ivec(bytes: sled::IVec) -> Self {
-        let array = bytes.as_ref().try_into().unwrap();
-        Self(array)
-    }
-}
-
 impl IntoSled for block::Height {
     type Bytes = [u8; 4];
 
@@ -274,3 +275,145 @@ impl SledDeserialize for sled::Tree {
         value_bytes.map(V::from_ivec)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use proptest::{arbitrary::any, prelude::*};
+    use std::ops::Deref;
+
+    impl Arbitrary for TransactionLocation {
+        type Parameters = ();
+
+        fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy {
+            (any::<block::Height>(), any::<u32>())
+                .prop_map(|(height, index)| Self { height, index })
+                .boxed()
+        }
+
+        type Strategy = BoxedStrategy<Self>;
+    }
+
+    fn round_trip<T>(input: T) -> T
+    where
+        T: IntoSled + FromSled,
+    {
+        let bytes = input.into_ivec();
+        T::from_ivec(bytes)
+    }
+
+    /// The round trip test covers types that are used as value field in a sled
+    /// Tree. Only these types are ever deserialized, and so they're the only
+    /// ones that implement both `IntoSled` and `FromSled`.
+    fn assert_round_trip<T>(input: T)
+    where
+        T: IntoSled + FromSled + Clone + PartialEq + std::fmt::Debug,
+    {
+        let before = input.clone();
+        let after = round_trip(input);
+        assert_eq!(before, after);
+    }
+
+    /// This test asserts that types that are used as sled keys behave correctly.
+    /// Any type that implements `IntoIVec` can be used as a sled key. The value
+    /// is serialized via `IntoSled::into_ivec` when the `key`, `value` pair is
+    /// inserted into the sled tree. The `as_bytes` impl on the other hand is
+    /// called for most other operations when comparing a key against existing
+    /// keys in the sled database, such as `contains`.
+    fn assert_as_bytes_matches_ivec<T>(input: T)
+    where
+        T: IntoSled + Clone,
+    {
+        let before = input.clone();
+        let ivec = input.into_ivec();
+        assert_eq!(before.as_bytes().as_ref(), ivec.as_ref());
+    }
+
+    #[test]
+    fn roundtrip_transaction_location() {
+        zebra_test::init();
+        proptest!(|(val in any::<TransactionLocation>())| assert_round_trip(val));
+    }
+
+    #[test]
+    fn roundtrip_block_hash() {
+        zebra_test::init();
+        proptest!(|(val in any::<block::Hash>())| assert_round_trip(val));
+    }
+
+    #[test]
+    fn roundtrip_block_height() {
+        zebra_test::init();
+        proptest!(|(val in any::<block::Height>())| assert_round_trip(val));
+    }
+
+    #[test]
+    fn roundtrip_block() {
+        zebra_test::init();
+
+        proptest!(|(block in any::<Block>())| {
+            let bytes = block.into_ivec();
+            let deserialized: Arc<Block> = FromSled::from_ivec(bytes);
+            assert_eq!(&block, deserialized.deref());
+        });
+    }
+
+    #[test]
+    fn roundtrip_transparent_output() {
+        zebra_test::init();
+
+        proptest!(|(block in any::<transparent::Output>())| {
+            let bytes = block.into_ivec();
+            let deserialized: transparent::Output = FromSled::from_ivec(bytes);
+            assert_eq!(block, deserialized);
+        });
+    }
+
+    #[test]
+    fn key_matches_ivec_transaction_location() {
+        zebra_test::init();
+        proptest!(|(val in any::<TransactionLocation>())| assert_as_bytes_matches_ivec(val));
+    }
+
+    #[test]
+    fn key_matches_ivec_trans_hash() {
+        zebra_test::init();
+        proptest!(|(val in any::<transaction::Hash>())| assert_as_bytes_matches_ivec(val));
+    }
+
+    #[test]
+    fn key_matches_ivec_block_hash() {
+        zebra_test::init();
+        proptest!(|(val in any::<block::Hash>())| assert_as_bytes_matches_ivec(val));
+    }
+
+    #[test]
+    fn key_matches_ivec_sprout_nullifier() {
+        zebra_test::init();
+        proptest!(|(val in any::<sprout::Nullifier>())| assert_as_bytes_matches_ivec(&val));
+    }
+
+    #[test]
+    fn key_matches_ivec_sapling_nullifier() {
+        zebra_test::init();
+        proptest!(|(val in any::<sapling::Nullifier>())| assert_as_bytes_matches_ivec(&val));
+    }
+
+    #[test]
+    fn key_matches_ivec_block_height() {
+        zebra_test::init();
+        proptest!(|(val in any::<block::Height>())| assert_as_bytes_matches_ivec(val));
+    }
+
+    #[test]
+    fn key_matches_ivec_transparent_output() {
+        zebra_test::init();
+        proptest!(|(val in any::<transparent::Output>())| assert_as_bytes_matches_ivec(&val));
+    }
+
+    #[test]
+    fn key_matches_ivec_transparent_outpoint() {
+        zebra_test::init();
+        proptest!(|(val in any::<transparent::OutPoint>())| assert_as_bytes_matches_ivec(val));
+    }
+}