Support resource leeway parameter when simulating Soroban transactions.

CHANGELOG.md

@@ -3,6 +3,12 @@
 A breaking change will get clearly marked in this log.
 
 
+## Unreleased
+
+### Added
+* `SorobanRpc.Server.simulateTransaction` now supports an optional `addlResources` parameter to allow users to specify additional resources that they want to include in a simulation ([#896](https://github.com/stellar/js-stellar-sdk/pull/896)).
+
+
 ## [v11.0.1](https://github.com/stellar/js-stellar-sdk/compare/v10.2.1...v11.0.0)
 
 ### Fixed

src/soroban/server.ts

@@ -40,6 +40,11 @@ export namespace Server {
     limit?: number;
   }
 
+  /** Describes additional resource leeways for transaction simulation. */
+  export interface ResourceLeeway {
+    cpuInstructions: number;
+  }
+
   export interface Options {
     allowHttp?: boolean;
     timeout?: number;
@@ -487,18 +492,28 @@ export class Server {
    * });
    */
   public async simulateTransaction(
-    transaction: Transaction | FeeBumpTransaction
+    tx: Transaction | FeeBumpTransaction,
+    addlResources?: Server.ResourceLeeway
   ): Promise<Api.SimulateTransactionResponse> {
-    return this._simulateTransaction(transaction).then(parseRawSimulation);
+    return this._simulateTransaction(tx, addlResources)
+      .then(parseRawSimulation);
   }
 
   public async _simulateTransaction(
-    transaction: Transaction | FeeBumpTransaction
+    transaction: Transaction | FeeBumpTransaction,
+    addlResources?: Server.ResourceLeeway
   ): Promise<Api.RawSimulateTransactionResponse> {
-    return jsonrpc.post(
+    return jsonrpc.postObject(
       this.serverURL.toString(),
       'simulateTransaction',
-      transaction.toXDR()
+      {
+        transaction: transaction.toXDR(),
+        ...(addlResources !== undefined && {
+          resourceConfig: {
+            instructionLeeway: addlResources.cpuInstructions
+          }
+        })
+      }
     );
   }
 

test/unit/server/soroban/simulate_transaction_test.js

@@ -81,7 +81,9 @@ describe("Server#simulateTransaction", async function (done) {
         jsonrpc: "2.0",
         id: 1,
         method: "simulateTransaction",
-        params: [this.blob],
+        params: {
+          transaction: this.blob
+        }
       })
       .returns(
         Promise.resolve({ data: { id: 1, result: simulationResponse } }),
@@ -98,6 +100,33 @@ describe("Server#simulateTransaction", async function (done) {
       });
   });
 
+  it("simulates a transaction with add'l resource usage", function (done) {
+    this.axiosMock
+      .expects("post")
+      .withArgs(serverUrl, {
+        jsonrpc: "2.0",
+        id: 1,
+        method: "simulateTransaction",
+        params: {
+          transaction: this.blob,
+          resourceConfig: { instructionLeeway: 100 }
+        }
+      })
+      .returns(
+        Promise.resolve({ data: { id: 1, result: simulationResponse } }),
+      );
+
+    this.server
+      .simulateTransaction(this.transaction, { cpuInstructions: 100 })
+      .then(function (response) {
+        expect(response).to.be.deep.equal(parsedSimulationResponse);
+        done();
+      })
+      .catch(function (err) {
+        done(err);
+      });
+  });
+
   it("works when there are no results", function () {
     const simResponse = baseSimulationResponse();
     const parsedCopy = cloneSimulation(parsedSimulationResponse);