➕ Add GetLatestBlockHash method (#38)

src/Solana.Unity.Rpc/IRpcClient.cs

@@ -367,6 +367,13 @@ Task<RequestResult<List<AccountKeyPair>>> GetProgramAccountsAsync(string pubKey,
         /// <returns>Returns a task that holds the asynchronous operation result and state.</returns>
         Task<RequestResult<ResponseValue<BlockHash>>> GetRecentBlockHashAsync(Commitment commitment = default);
 
+        /// <summary>
+        /// Gets the latest block hash.
+        /// </summary>
+        /// <param name="commitment">The state commitment to consider when querying the ledger state.</param>
+        /// <returns>Returns a task that holds the asynchronous operation result and state.</returns>
+        Task<RequestResult<ResponseValue<LatestBlockHash>>> GetLatestBlockHashAsync(Commitment commitment = Commitment.Finalized);
+
         /// <summary>
         /// Gets a list of recent performance samples.
         /// <remarks>

src/Solana.Unity.Rpc/Models/Block.cs

@@ -361,4 +361,21 @@ public class BlockHash
         /// </summary>
         public FeeCalculator FeeCalculator { get; set; }
     }
+
+
+    /// <summary>
+    /// Represents the latest block hash info.
+    /// </summary>
+    public class LatestBlockHash
+    {
+        /// <summary>
+        /// A base-58 encoded string representing the block hash.
+        /// </summary>
+        public string Blockhash { get; set; }
+
+        /// <summary>
+        /// The last block height at which the blockhash will be valid.
+        /// </summary>
+        public ulong LastValidBlockHeight { get; set; }
+    }
 }

src/Solana.Unity.Rpc/SolanaRpcClient.cs

@@ -62,7 +62,6 @@ private JsonRpcRequest BuildRequest<T>(string method, IList<object> parameters)
         private async Task<RequestResult<T>> SendRequestAsync<T>(string method)
         {
             JsonRpcRequest req = BuildRequest<T>(method, null);
-
             return await SendRequest<T>(req);
         }
 
@@ -564,6 +563,14 @@ public async Task<RequestResult<ResponseValue<BlockHash>>> GetRecentBlockHashAsy
         /// <inheritdoc cref="IRpcClient.GetRecentBlockHash"/>
         public RequestResult<ResponseValue<BlockHash>> GetRecentBlockHash(Commitment commitment = default)
             => GetRecentBlockHashAsync(commitment).Result;
+
+        /// <inheritdoc cref="IRpcClient.GetLatestBlockHashAsync"/>
+        public async Task<RequestResult<ResponseValue<LatestBlockHash>>> GetLatestBlockHashAsync(
+            Commitment commitment = Commitment.Finalized)
+        {
+            return await SendRequestAsync<ResponseValue<LatestBlockHash>>("getLatestBlockhash",
+                Parameters.Create(ConfigObject.Create(HandleCommitment(commitment))));
+        }
 
         /// <inheritdoc cref="IRpcClient.GetMaxRetransmitSlotAsync"/>
         public async Task<RequestResult<ulong>> GetMaxRetransmitSlotAsync()

test/Solana.Unity.Rpc.Test/Resources/Http/Blocks/GetLatestBlockhashRequest.json

@@ -0,0 +1 @@
+{"method":"getLatestBlockhash","jsonrpc":"2.0","id":0}

test/Solana.Unity.Rpc.Test/Resources/Http/Blocks/GetLatestBlockhashResponse.json

@@ -0,0 +1 @@
+{"jsonrpc":"2.0","result":{"context":{"slot":127140942},"value":{"blockhash":"DDFfxGAsEVcqNbCLRgvDtzcc2ZxNnqJfQJfMTRhEEPwW","lastValidBlockHeight":115143990}},"id":0}

test/Solana.Unity.Rpc.Test/Solana.Unity.Rpc.Test.csproj

@@ -390,6 +390,12 @@
     <None Update="Resources\Http\GetRecentBlockhashRequest.json">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>
+    <None Update="Resources\Http\Blocks\GetLatestBlockhashRequest.json">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+    <None Update="Resources\Http\Blocks\GetLatestBlockhashResponse.json">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
     <None Update="Resources\Http\Transaction\SimulateTransactionRequest.json">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>

test/Solana.Unity.Rpc.Test/SolanaRpcClientBlockTests.cs

@@ -979,6 +979,33 @@ public void TestGetRecentBlockHash()
 
             FinishTest(messageHandlerMock, TestnetUri);
         }
+
+        [TestMethod]
+        public async Task TestGetLatestBlockHash()
+        {
+            var responseData = File.ReadAllText("Resources/Http/Blocks/GetLatestBlockhashResponse.json");
+            var requestData = File.ReadAllText("Resources/Http/Blocks/GetLatestBlockhashRequest.json");
+            var sentMessage = string.Empty;
+            var messageHandlerMock = SetupTest(
+                (s => sentMessage = s), responseData);
+
+            var httpClient = new HttpClient(messageHandlerMock.Object)
+            {
+                BaseAddress = TestnetUri,
+            };
+
+            var sut = new SolanaRpcClient(TestnetUrl, null, httpClient);
+            var result = await sut.GetLatestBlockHashAsync();
+
+            Assert.AreEqual(requestData, sentMessage);
+            Assert.IsNotNull(result.Result);
+            Assert.IsTrue(result.WasSuccessful);
+            Assert.AreEqual(127140942UL, result.Result.Context.Slot);
+            Assert.AreEqual("DDFfxGAsEVcqNbCLRgvDtzcc2ZxNnqJfQJfMTRhEEPwW", result.Result.Value.Blockhash);
+            Assert.AreEqual(115143990UL, result.Result.Value.LastValidBlockHeight);
+
+            FinishTest(messageHandlerMock, TestnetUri);
+        }
 
         [TestMethod]
         public void TestGetRecentBlockHashProcessed()