feat(net): Arbitrary Payload Hash (#75)

### Description

Adds an `Arbitrary` impl for the `PayloadHash` type.

Cargo.toml

@@ -135,6 +135,7 @@ alloy = { version = "0.2", features = [
     "signers",
     "consensus",
 ] }
+alloy-primitives = { version = "0.8", features = ["serde"] }
 alloy-rlp = "0.3.4"
 
 # Tokio

crates/net/Cargo.toml

@@ -40,7 +40,8 @@ arbitrary = { workspace = true, optional = true }
 [dev-dependencies]
 arbtest.workspace = true
 arbitrary.workspace = true
+alloy = { workspace = true, features = ["arbitrary"] }
 
 [features]
 default = []
-arbitrary = ["dep:arbitrary"]
+arbitrary = ["dep:arbitrary", "alloy/arbitrary"]

crates/net/src/types/payload.rs

@@ -15,6 +15,7 @@ type Transaction = List<u8, 1073741824>;
 
 /// Represents the Keccak256 hash of the block
 #[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
+#[cfg_attr(any(test, feature = "arbitrary"), derive(arbitrary::Arbitrary))]
 pub struct PayloadHash(B256);
 
 impl From<&[u8]> for PayloadHash {
@@ -281,4 +282,14 @@ mod tests {
         let expected = b256!("44a0e2b1aba1aae1771eddae1dcd2ad18a8cdac8891517153f03253e49d3f206");
         assert_eq!(hash.signature_message(chain_id), expected);
     }
+
+    #[test]
+    fn test_inner_payload_hash() {
+        arbtest::arbtest(|u| {
+            let inner = B256::from(u.arbitrary::<[u8; 32]>()?);
+            let hash = PayloadHash::from(inner.as_slice());
+            assert_eq!(hash.0, keccak256(inner.as_slice()));
+            Ok(())
+        });
+    }
 }