BESU-146 - return better gas estimate service error message if possible (#436)

Signed-off-by: Anthony Buckle <anthonybuckle@gmail.com>

ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/jsonrpc/internal/methods/EthEstimateGas.java

@@ -14,6 +14,7 @@
  */
 package org.hyperledger.besu.ethereum.api.jsonrpc.internal.methods;
 
+import org.hyperledger.besu.ethereum.api.jsonrpc.JsonRpcErrorConverter;
 import org.hyperledger.besu.ethereum.api.jsonrpc.RpcMethod;
 import org.hyperledger.besu.ethereum.api.jsonrpc.internal.JsonRpcRequestContext;
 import org.hyperledger.besu.ethereum.api.jsonrpc.internal.parameters.JsonCallParameter;
@@ -24,6 +25,8 @@ import org.hyperledger.besu.ethereum.api.jsonrpc.internal.response.JsonRpcSucces
 import org.hyperledger.besu.ethereum.api.jsonrpc.internal.results.Quantity;
 import org.hyperledger.besu.ethereum.api.query.BlockchainQueries;
 import org.hyperledger.besu.ethereum.core.BlockHeader;
+import org.hyperledger.besu.ethereum.mainnet.TransactionValidator;
+import org.hyperledger.besu.ethereum.mainnet.ValidationResult;
 import org.hyperledger.besu.ethereum.transaction.CallParameter;
 import org.hyperledger.besu.ethereum.transaction.TransactionSimulator;
 import org.hyperledger.besu.ethereum.transaction.TransactionSimulatorResult;
@@ -53,7 +56,7 @@ public class EthEstimateGas implements JsonRpcMethod {
 
     final BlockHeader blockHeader = blockHeader();
     if (blockHeader == null) {
-      return errorResponse(requestContext);
+      return errorResponse(requestContext, JsonRpcError.INTERNAL_ERROR);
     }
 
     final JsonCallParameter modifiedCallParams =
@@ -62,7 +65,7 @@ public class EthEstimateGas implements JsonRpcMethod {
     return transactionSimulator
         .process(modifiedCallParams, blockHeader.getNumber())
         .map(gasEstimateResponse(requestContext))
-        .orElse(errorResponse(requestContext));
+        .orElse(errorResponse(requestContext, JsonRpcError.INTERNAL_ERROR));
   }
 
   private BlockHeader blockHeader() {
@@ -87,10 +90,25 @@ public class EthEstimateGas implements JsonRpcMethod {
         result.isSuccessful()
             ? new JsonRpcSuccessResponse(
                 request.getRequest().getId(), Quantity.create(result.getGasEstimate()))
-            : null;
+            : errorResponse(request, result.getValidationResult());
   }
 
-  private JsonRpcErrorResponse errorResponse(final JsonRpcRequestContext request) {
-    return new JsonRpcErrorResponse(request.getRequest().getId(), JsonRpcError.INTERNAL_ERROR);
+  private JsonRpcErrorResponse errorResponse(
+      final JsonRpcRequestContext request,
+      final ValidationResult<TransactionValidator.TransactionInvalidReason> validationResult) {
+    JsonRpcError jsonRpcError = null;
+    if (validationResult != null) {
+      jsonRpcError =
+          JsonRpcErrorConverter.convertTransactionInvalidReason(
+              validationResult.getInvalidReason());
+    }
+    return errorResponse(request, jsonRpcError);
+  }
+
+  private JsonRpcErrorResponse errorResponse(
+      final JsonRpcRequestContext request, final JsonRpcError jsonRpcError) {
+    return new JsonRpcErrorResponse(
+        request.getRequest().getId(),
+        jsonRpcError == null ? JsonRpcError.INTERNAL_ERROR : jsonRpcError);
   }
 }

ethereum/api/src/test/java/org/hyperledger/besu/ethereum/api/jsonrpc/internal/methods/EthEstimateGasTest.java

@@ -30,6 +30,8 @@ import org.hyperledger.besu.ethereum.api.jsonrpc.internal.results.Quantity;
 import org.hyperledger.besu.ethereum.api.query.BlockchainQueries;
 import org.hyperledger.besu.ethereum.chain.Blockchain;
 import org.hyperledger.besu.ethereum.core.BlockHeader;
+import org.hyperledger.besu.ethereum.mainnet.TransactionValidator.TransactionInvalidReason;
+import org.hyperledger.besu.ethereum.mainnet.ValidationResult;
 import org.hyperledger.besu.ethereum.transaction.CallParameter;
 import org.hyperledger.besu.ethereum.transaction.TransactionSimulator;
 import org.hyperledger.besu.ethereum.transaction.TransactionSimulatorResult;
@@ -105,13 +107,37 @@ public class EthEstimateGasTest {
         .isEqualToComparingFieldByField(expectedResponse);
   }
 
+  @Test
+  public void shouldReturnErrorWhenTransactionProcessorReturnsTxInvalidReason() {
+    final JsonRpcRequestContext request = ethEstimateGasRequest(callParameter());
+    mockTransientProcessorResultTxInvalidReason(
+        TransactionInvalidReason.UPFRONT_COST_EXCEEDS_BALANCE);
+
+    final JsonRpcResponse expectedResponse =
+        new JsonRpcErrorResponse(null, JsonRpcError.TRANSACTION_UPFRONT_COST_EXCEEDS_BALANCE);
+
+    Assertions.assertThat(method.response(request))
+        .isEqualToComparingFieldByField(expectedResponse);
+  }
+
+  private void mockTransientProcessorResultTxInvalidReason(final TransactionInvalidReason reason) {
+    final TransactionSimulatorResult mockTxSimResult = getMockTransactionSimulatorResult(false);
+    when(mockTxSimResult.getValidationResult()).thenReturn(ValidationResult.invalid(reason));
+  }
+
   private void mockTransientProcessorResultGasEstimate(
       final long gasEstimate, final boolean isSuccessful) {
-    final TransactionSimulatorResult result = mock(TransactionSimulatorResult.class);
-    when(result.getGasEstimate()).thenReturn(gasEstimate);
+    final TransactionSimulatorResult mockTxSimResult =
+        getMockTransactionSimulatorResult(isSuccessful);
+    when(mockTxSimResult.getGasEstimate()).thenReturn(gasEstimate);
+  }
+
+  private TransactionSimulatorResult getMockTransactionSimulatorResult(final boolean isSuccessful) {
+    final TransactionSimulatorResult mockTxSimResult = mock(TransactionSimulatorResult.class);
     when(transactionSimulator.process(eq(modifiedCallParameter()), eq(1L)))
-        .thenReturn(Optional.of(result));
-    when(result.isSuccessful()).thenReturn(isSuccessful);
+        .thenReturn(Optional.of(mockTxSimResult));
+    when(mockTxSimResult.isSuccessful()).thenReturn(isSuccessful);
+    return mockTxSimResult;
   }
 
   private JsonCallParameter callParameter() {