feat(eips): Make prague field an enum (#1574)

* Update eip7685.rs

* Update crates/eips/src/eip7685.rs

Co-authored-by: Thomas Coratger <[email protected]>

* Update crates/eips/src/eip7685.rs

Co-authored-by: Thomas Coratger <[email protected]>

* Update sidecar.rs

* Update sidecar.rs

* Update sidecar.rs

* Update eip7685.rs

* Update eip7685.rs

* Update eip7685.rs

* Update eip7685.rs

* Update eip7685.rs

* Update sidecar.rs

* Update crates/eips/src/eip7685.rs

Co-authored-by: Oliver <[email protected]>

* Update sidecar.rs

* Update eip7685.rs

* Update crates/rpc-types-engine/src/sidecar.rs

Co-authored-by: Oliver <[email protected]>

* Update sidecar.rs

* Update sidecar.rs

* touchups

---------

Co-authored-by: Thomas Coratger <[email protected]>
Co-authored-by: Oliver <[email protected]>
Co-authored-by: Matthias Seitz <[email protected]>

crates/eips/src/eip7685.rs

@@ -75,6 +75,55 @@ impl Requests {
     }
 }
 
+/// A list of requests or a precomputed requests hash.
+///
+/// For testing purposes, the `Hash` variant stores a precomputed requests hash. This can be useful
+/// when the exact contents of the requests are unnecessary, and only a consistent hash value is
+/// needed to simulate the presence of requests without holding actual data.
+#[derive(Debug, Clone, PartialEq, Eq, Hash, derive_more::From)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+pub enum RequestsOrHash {
+    /// Stores a list of requests, allowing for dynamic requests hash calculation.
+    Requests(Requests),
+    /// Stores a precomputed requests hash, used primarily for testing or mocking because the
+    /// header only contains the hash.
+    Hash(B256),
+}
+
+impl RequestsOrHash {
+    /// Returns the requests hash for the enum instance.
+    ///
+    /// - If the instance contains a list of requests, this function calculates the hash using
+    ///   `requests_hash` of the [`Requests`] struct.
+    /// - If it contains a precomputed hash, it returns that hash directly.
+    #[cfg(feature = "sha2")]
+    pub fn requests_hash(&self) -> B256 {
+        match self {
+            Self::Requests(requests) => requests.requests_hash(),
+            Self::Hash(precomputed_hash) => *precomputed_hash,
+        }
+    }
+
+    /// Returns an instance with the [`EMPTY_REQUESTS_HASH`].
+    pub const fn empty() -> Self {
+        Self::Hash(EMPTY_REQUESTS_HASH)
+    }
+
+    /// Returns the requests, if any.
+    pub const fn requests(&self) -> Option<&Requests> {
+        match self {
+            Self::Requests(requests) => Some(requests),
+            Self::Hash(_) => None,
+        }
+    }
+}
+
+impl Default for RequestsOrHash {
+    fn default() -> Self {
+        Self::Requests(Requests::default())
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

crates/rpc-types-engine/src/cancun.rs

@@ -2,7 +2,6 @@
 //! beacon consensus engine.
 
 use alloc::vec::Vec;
-
 use alloy_primitives::B256;
 
 /// Fields introduced in `engine_newPayloadV3` that are not present in the `ExecutionPayload` RPC
@@ -20,6 +19,13 @@ pub struct CancunPayloadFields {
     pub versioned_hashes: Vec<B256>,
 }
 
+impl CancunPayloadFields {
+    /// Returns a new [`CancunPayloadFields`] instance.
+    pub const fn new(parent_beacon_block_root: B256, versioned_hashes: Vec<B256>) -> Self {
+        Self { parent_beacon_block_root, versioned_hashes }
+    }
+}
+
 /// A container type for [CancunPayloadFields] that may or may not be present.
 #[derive(Clone, Debug, Default, PartialEq, Eq, Hash)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]

crates/rpc-types-engine/src/prague.rs

@@ -1,19 +1,27 @@
 //! Contains types related to the Prague hardfork that will be used by RPC to communicate with the
 //! beacon consensus engine.
 
-use alloy_eips::eip7685::Requests;
+use alloy_eips::eip7685::{Requests, RequestsOrHash};
+use alloy_primitives::B256;
 
 /// Fields introduced in `engine_newPayloadV4` that are not present in the `ExecutionPayload` RPC
 /// object.
 #[derive(Clone, Debug, Default, PartialEq, Eq, Hash)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct PraguePayloadFields {
     /// EIP-7685 requests.
-    pub requests: Requests,
+    pub requests: RequestsOrHash,
     /// EIP-7742 target number of blobs in the block.
     pub target_blobs_per_block: u64,
 }
 
+impl PraguePayloadFields {
+    /// Returns a new [`PraguePayloadFields`] instance.
+    pub fn new(requests: impl Into<RequestsOrHash>, target_blobs_per_block: u64) -> Self {
+        Self { requests: requests.into(), target_blobs_per_block }
+    }
+}
+
 /// A container type for [PraguePayloadFields] that may or may not be present.
 #[derive(Clone, Debug, Default, PartialEq, Eq, Hash)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
@@ -34,14 +42,23 @@ impl MaybePraguePayloadFields {
 
     /// Returns the requests, if any.
     pub fn requests(&self) -> Option<&Requests> {
-        self.fields.as_ref().map(|fields| &fields.requests)
+        self.fields.as_ref().and_then(|fields| fields.requests.requests())
     }
 
     /// Returns the target blobs per block, if any.
     pub fn target_blobs_per_block(&self) -> Option<u64> {
         self.fields.as_ref().map(|fields| fields.target_blobs_per_block)
     }
 
+    /// Calculates or retrieves the requests hash.
+    ///
+    /// - If the `prague` field contains a list of requests, it calculates the requests hash
+    ///   dynamically.
+    /// - If it contains a precomputed hash (used for testing), it returns that hash directly.
+    pub fn requests_hash(&self) -> Option<B256> {
+        self.fields.as_ref().map(|fields| fields.requests.requests_hash())
+    }
+
     /// Returns a reference to the inner fields.
     pub const fn as_ref(&self) -> Option<&PraguePayloadFields> {
         self.fields.as_ref()

crates/rpc-types-engine/src/sidecar.rs

@@ -57,10 +57,22 @@ impl ExecutionPayloadSidecar {
     }
 
     /// Returns the EIP-7685 requests
+    ///
+    /// Note: if the [`PraguePayloadFields`] only contains the requests hash this will return
+    /// `None`.
     pub fn requests(&self) -> Option<&Requests> {
         self.prague.requests()
     }
 
+    /// Calculates or retrieves the requests hash.
+    ///
+    /// - If the `prague` field contains a list of requests, it calculates the requests hash
+    ///   dynamically.
+    /// - If it contains a precomputed hash (used for testing), it returns that hash directly.
+    pub fn requests_hash(&self) -> Option<B256> {
+        self.prague.requests_hash()
+    }
+
     /// Returns the target blobs per block
     pub fn target_blobs_per_block(&self) -> Option<u64> {
         self.prague.target_blobs_per_block()