feat(rpc): introduce getblocktemplate rpc call with stub fields

zebra-rpc/src/methods/get_block_template.rs

@@ -35,8 +35,19 @@ pub trait GetBlockTemplateRpc {
     ///
     /// - If `index` is positive then index = block height.
     /// - If `index` is negative then -1 is the last known valid block.
+    /// - This rpc method is available only if zebra is built with `--features getblocktemplate-rpcs`.
     #[rpc(name = "getblockhash")]
     fn get_block_hash(&self, index: i32) -> BoxFuture<Result<GetBlockHash>>;
+
+    /// Documentation to be filled as we go.
+    ///
+    /// zcashd reference: [`getblocktemplate`](https://zcash-rpc.github.io/getblocktemplate.html)
+    ///
+    /// # Notes
+    ///
+    /// - This rpc method is available only if zebra is built with `--features getblocktemplate-rpcs`.
+    #[rpc(name = "getblocktemplate")]
+    fn get_block_template(&self) -> BoxFuture<Result<GetBlockTemplate>>;
 }
 
 /// RPC method implementations.
@@ -139,8 +150,118 @@ where
         }
         .boxed()
     }
+
+    fn get_block_template(&self) -> BoxFuture<Result<GetBlockTemplate>> {
+        async move {
+            let empty_string = String::from("");
+
+            // Returns empty `GetBlockTemplate`
+            Ok(GetBlockTemplate {
+                capabilities: vec![],
+                version: 0,
+                previous_block_hash: empty_string.clone(),
+                block_commitments_hash: empty_string.clone(),
+                light_client_root_hash: empty_string.clone(),
+                final_sapling_root_hash: empty_string.clone(),
+                default_roots: DefaultRoots {
+                    merkle_root: empty_string.clone(),
+                    chain_history_root: empty_string.clone(),
+                    auth_data_root: empty_string.clone(),
+                    block_commitments_hash: empty_string.clone(),
+                },
+                transactions: vec![],
+                coinbase_txn: Coinbase {},
+                target: empty_string.clone(),
+                min_time: 0,
+                mutable: vec![],
+                nonce_range: empty_string.clone(),
+                sigop_limit: 0,
+                size_limit: 0,
+                cur_time: 0,
+                bits: empty_string,
+                height: 0,
+            })
+        }
+        .boxed()
+    }
+}
+/// Documentation to be added after we document all the individual fields.
+#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize, serde::Deserialize)]
+pub struct GetBlockTemplate {
+    /// Add documentation.
+    pub capabilities: Vec<String>,
+    /// Add documentation.
+    pub version: usize,
+    /// Add documentation.
+    #[serde(rename = "previousblockhash")]
+    pub previous_block_hash: String,
+    /// Add documentation.
+    #[serde(rename = "blockcommitmentshash")]
+    pub block_commitments_hash: String,
+    /// Add documentation.
+    #[serde(rename = "lightclientroothash")]
+    pub light_client_root_hash: String,
+    /// Add documentation.
+    #[serde(rename = "finalsaplingroothash")]
+    pub final_sapling_root_hash: String,
+    /// Add documentation.
+    #[serde(rename = "defaultroots")]
+    pub default_roots: DefaultRoots,
+    /// Add documentation.
+    pub transactions: Vec<Transaction>,
+    /// Add documentation.
+    #[serde(rename = "coinbasetxn")]
+    pub coinbase_txn: Coinbase,
+    /// Add documentation.
+    pub target: String,
+    /// Add documentation.
+    #[serde(rename = "mintime")]
+    pub min_time: u32,
+    /// Add documentation.
+    pub mutable: Vec<String>,
+    /// Add documentation.
+    #[serde(rename = "noncerange")]
+    pub nonce_range: String,
+    /// Add documentation.
+    #[serde(rename = "sigoplimit")]
+    pub sigop_limit: u32,
+    /// Add documentation.
+    #[serde(rename = "sizelimit")]
+    pub size_limit: u32,
+    /// Add documentation.
+    #[serde(rename = "curtime")]
+    pub cur_time: u32,
+    /// Add documentation.
+    pub bits: String,
+    /// Add documentation.
+    pub height: u32,
 }
 
+/// Documentation to be added in #5452 or #5455.
+#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize, serde::Deserialize)]
+pub struct DefaultRoots {
+    /// Add documentation.
+    #[serde(rename = "merkleroot")]
+    pub merkle_root: String,
+    /// Add documentation.
+    #[serde(rename = "chainhistoryroot")]
+    pub chain_history_root: String,
+    /// Add documentation.
+    #[serde(rename = "authdataroot")]
+    pub auth_data_root: String,
+    /// Add documentation.
+    #[serde(rename = "blockcommitmentshash")]
+    pub block_commitments_hash: String,
+}
+
+/// Documentation and fields to be added in #5454.
+#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize, serde::Deserialize)]
+pub struct Transaction {}
+
+/// documentation and fields to be added in #5453.
+#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize, serde::Deserialize)]
+pub struct Coinbase {}
+
 /// Given a potentially negative index, find the corresponding `Height`.
 ///
 /// This function is used to parse the integer index argument of `get_block_hash`.

zebra-rpc/src/methods/tests/snapshot.rs

@@ -191,6 +191,13 @@ async fn test_rpc_response_data_for_network(network: Network) {
             .expect("We should have a GetBlockHash struct");
 
         snapshot_rpc_getblockhash(get_block_hash, &settings);
+
+        // `getblocktemplate`
+        let get_block_template = get_block_template_rpc
+            .get_block_template()
+            .await
+            .expect("We should have a GetBlockTemplate struct");
+        snapshot_rpc_getblocktemplate(get_block_template, &settings);
     }
 }
 
@@ -292,6 +299,15 @@ fn snapshot_rpc_getblockhash(block_hash: GetBlockHash, settings: &insta::Setting
     settings.bind(|| insta::assert_json_snapshot!("get_block_hash", block_hash));
 }
 
+#[cfg(feature = "getblocktemplate-rpcs")]
+/// Snapshot `getblocktemplate` response, using `cargo insta` and JSON serialization.
+fn snapshot_rpc_getblocktemplate(
+    block_template: crate::methods::get_block_template::GetBlockTemplate,
+    settings: &insta::Settings,
+) {
+    settings.bind(|| insta::assert_json_snapshot!("get_block_template", block_template));
+}
+
 /// Utility function to convert a `Network` to a lowercase string.
 fn network_string(network: Network) -> String {
     let mut net_suffix = network.to_string();

zebra-rpc/src/methods/tests/snapshots/get_block_template@mainnet_10.snap

@@ -0,0 +1,30 @@
+---
+source: zebra-rpc/src/methods/tests/snapshot.rs
+assertion_line: 308
+expression: block_template
+---
+{
+  "capabilities": [],
+  "version": 0,
+  "previousblockhash": "",
+  "blockcommitmentshash": "",
+  "lightclientroothash": "",
+  "finalsaplingroothash": "",
+  "defaultroots": {
+    "merkleroot": "",
+    "chainhistoryroot": "",
+    "authdataroot": "",
+    "blockcommitmentshash": ""
+  },
+  "transactions": [],
+  "coinbasetxn": {},
+  "target": "",
+  "mintime": 0,
+  "mutable": [],
+  "noncerange": "",
+  "sigoplimit": 0,
+  "sizelimit": 0,
+  "curtime": 0,
+  "bits": "",
+  "height": 0
+}

zebra-rpc/src/methods/tests/snapshots/get_block_template@testnet_10.snap

@@ -0,0 +1,30 @@
+---
+source: zebra-rpc/src/methods/tests/snapshot.rs
+assertion_line: 308
+expression: block_template
+---
+{
+  "capabilities": [],
+  "version": 0,
+  "previousblockhash": "",
+  "blockcommitmentshash": "",
+  "lightclientroothash": "",
+  "finalsaplingroothash": "",
+  "defaultroots": {
+    "merkleroot": "",
+    "chainhistoryroot": "",
+    "authdataroot": "",
+    "blockcommitmentshash": ""
+  },
+  "transactions": [],
+  "coinbasetxn": {},
+  "target": "",
+  "mintime": 0,
+  "mutable": [],
+  "noncerange": "",
+  "sigoplimit": 0,
+  "sizelimit": 0,
+  "curtime": 0,
+  "bits": "",
+  "height": 0
+}

zebra-rpc/src/methods/tests/vectors.rs

@@ -757,3 +757,70 @@ async fn rpc_getblockhash() {
 
     mempool.expect_no_requests().await;
 }
+
+#[cfg(feature = "getblocktemplate-rpcs")]
+#[tokio::test(flavor = "multi_thread")]
+async fn rpc_getblocktemplate() {
+    let _init_guard = zebra_test::init();
+
+    // Create a continuous chain of mainnet blocks from genesis
+    let blocks: Vec<Arc<Block>> = zebra_test::vectors::CONTINUOUS_MAINNET_BLOCKS
+        .iter()
+        .map(|(_height, block_bytes)| block_bytes.zcash_deserialize_into().unwrap())
+        .collect();
+
+    let mut mempool: MockService<_, _, _, BoxError> = MockService::build().for_unit_tests();
+    // Create a populated state service
+    let (_state, read_state, latest_chain_tip, _chain_tip_change) =
+        zebra_state::populated_state(blocks.clone(), Mainnet).await;
+
+    // Init RPCs
+    let _rpc = RpcImpl::new(
+        "RPC test",
+        Mainnet,
+        false,
+        Buffer::new(mempool.clone(), 1),
+        Buffer::new(read_state.clone(), 1),
+        latest_chain_tip.clone(),
+    );
+    let get_block_template_rpc =
+        get_block_template::GetBlockTemplateRpcImpl::new(latest_chain_tip, read_state);
+
+    let get_block_template = get_block_template_rpc
+        .get_block_template()
+        .await
+        .expect("We should have a GetBlockTemplate struct");
+
+    assert!(get_block_template.capabilities.is_empty());
+    assert_eq!(get_block_template.version, 0);
+    assert!(get_block_template.previous_block_hash.is_empty());
+    assert!(get_block_template.block_commitments_hash.is_empty());
+    assert!(get_block_template.light_client_root_hash.is_empty());
+    assert!(get_block_template.final_sapling_root_hash.is_empty());
+    assert!(get_block_template.default_roots.merkle_root.is_empty());
+    assert!(get_block_template
+        .default_roots
+        .chain_history_root
+        .is_empty());
+    assert!(get_block_template.default_roots.auth_data_root.is_empty());
+    assert!(get_block_template
+        .default_roots
+        .block_commitments_hash
+        .is_empty());
+    assert!(get_block_template.transactions.is_empty());
+    assert_eq!(
+        get_block_template.coinbase_txn,
+        get_block_template::Coinbase {}
+    );
+    assert!(get_block_template.target.is_empty());
+    assert_eq!(get_block_template.min_time, 0);
+    assert!(get_block_template.mutable.is_empty());
+    assert!(get_block_template.nonce_range.is_empty());
+    assert_eq!(get_block_template.sigop_limit, 0);
+    assert_eq!(get_block_template.size_limit, 0);
+    assert_eq!(get_block_template.cur_time, 0);
+    assert!(get_block_template.bits.is_empty());
+    assert_eq!(get_block_template.height, 0);
+
+    mempool.expect_no_requests().await;
+}