fix: set correct gasCost values in debug_traceTransaction (#578)

trufflesuite · Jun 23, 2020 · ee8972e · ee8972e
1 parent ad91e80
commit ee8972e
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Showing 2 changed files with 10 additions and 5 deletions.
diff --git a/lib/blockchain_double.js b/lib/blockchain_double.js
@@ -844,8 +844,8 @@ BlockchainDouble.prototype.processTransactionTrace = async function(hash, params
 
     const gasLeft = to.number(event.gasLeft);
     const totalGasUsedAfterThisStep = to.number(txCurrentlyProcessing.gasLimit) - gasLeft;
-    const gasUsedThisStep = totalGasUsedAfterThisStep - returnVal.gas;
-    returnVal.gas += gasUsedThisStep;
+    const gasUsedPreviousStep = totalGasUsedAfterThisStep - returnVal.gas;
+    returnVal.gas += gasUsedPreviousStep;
 
     let memory = null;
     if (!params.disableMemory) {
@@ -868,19 +868,24 @@ BlockchainDouble.prototype.processTransactionTrace = async function(hash, params
         return to.rpcDataHexString(item, 64).replace("0x", ""); // non-0x prefixed.
       });
     }
-
     let structLog = {
       depth: event.depth,
       error: "",
       gas: gasLeft,
-      gasCost: gasUsedThisStep,
+      gasCost: 0,
       memory,
       op: event.opcode.name,
       pc: event.pc,
       stack,
       storage: null
     };
 
+    // The gas difference calculated for each step is indicative of gas consumed in
+    // the previous step. Gas consumption in the final step will always be zero.
+    if (returnVal.structLogs.length) {
+      returnVal.structLogs[returnVal.structLogs.length - 1].gasCost = gasUsedPreviousStep;
+    }
+
     if (params.disableStorage) {
       returnVal.structLogs.push(structLog);
       next();

diff --git a/test/debug/debug.js b/test/debug/debug.js
@@ -151,7 +151,7 @@ function test(forked) {
       const lastop = structLogs[structLogs.length - 1];
 
       assert.strictEqual(lastop.op, "STOP");
-      assert.strictEqual(lastop.gasCost, 1);
+      assert.strictEqual(lastop.gasCost, 0);
       assert.strictEqual(lastop.pc, 235);
       assert.strictEqual(
         lastop.storage["0000000000000000000000000000000000000000000000000000000000000000"],