fix: update simulationData after re-simulation

The new test added here shows that you can edit a transaction with
`tx.raw = cloneFrom(tx.build)` and that the `tx.simulationData` will be
updated correctly.

CHANGELOG.md

@@ -6,6 +6,10 @@ A breaking change will get clearly marked in this log.
 
 ## Unreleased
 
+### Fixed
+
+- Contract Client: if you edit an `AssembledTransaction` with `tx.raw = cloneFrom(tx.build)`, the `tx.simulationData` will now be updated correctly. `simulationData` is effectively a cache, and we now make sure we clear it when you re-simulate.
+
 
 ## [v12.0.1](https://github.com/stellar/js-stellar-sdk/compare/v11.3.0...v12.0.1)
 

src/contract/assembled_transaction.ts

@@ -422,6 +422,10 @@ export class AssembledTransaction<T> {
     this.built = this.raw.build();
     this.simulation = await this.server.simulateTransaction(this.built);
 
+    // need to force re-calculation of simulationData for new simulation
+    delete this.simulationResult;
+    delete this.simulationTransactionData;
+
     if (Api.isSimulationSuccess(this.simulation)) {
       this.built = assembleTransaction(
         this.built,

test/e2e/src/test-swap.js

@@ -1,7 +1,17 @@
-const { expect } = require('chai');
-const { describe, it, before } = require('mocha');
-const { contract, rpc } = require("../../..");
-const { clientFor, generateFundedKeypair } = require("./util");
+const { expect } = require("chai");
+const { describe, it, before } = require("mocha");
+const {
+  contract,
+  rpc,
+  SorobanDataBuilder,
+  xdr,
+  TransactionBuilder,
+} = require("../../..");
+const {
+  clientFor,
+  generateFundedKeypair,
+  networkPassphrase,
+} = require("./util");
 
 const amountAToSwap = 2n;
 const amountBToSwap = 1n;
@@ -74,14 +84,60 @@ describe("Swap Contract Tests", function () {
       // Further assertions on the error object
       expect(error).to.be.instanceOf(contract.AssembledTransaction.Errors.NeedsMoreSignatures,
         `error is not of type 'NeedsMoreSignaturesError'; instead it is of type '${error?.constructor.name}'`);
-      
+
       if (error) {
         // Using regex to check the error message
         expect(error.message).to.match(/needsNonInvokerSigningBy/);
       }
     });
   });
 
+  it("modified & re-simulated transactions show updated data", async function () {
+    const tx = await this.context.swapContractAsRoot.swap({
+      a: this.context.alice.publicKey(),
+      b: this.context.bob.publicKey(),
+      token_a: this.context.tokenAId,
+      token_b: this.context.tokenBId,
+      amount_a: amountAToSwap,
+      min_a_for_b: amountAToSwap,
+      amount_b: amountBToSwap,
+      min_b_for_a: amountBToSwap,
+    });
+    await tx.signAuthEntries({
+      publicKey: this.context.alice.publicKey(),
+      ...contract.basicNodeSigner(this.context.alice, networkPassphrase),
+    });
+    await tx.signAuthEntries({
+      publicKey: this.context.bob.publicKey(),
+      ...contract.basicNodeSigner(this.context.bob, networkPassphrase),
+    });
+
+    const originalResourceFee = Number(
+      tx.simulationData.transactionData.resourceFee()
+    );
+    const bumpedResourceFee = originalResourceFee + 10000;
+
+    tx.raw = TransactionBuilder.cloneFrom(tx.built, {
+      fee: tx.built.fee,
+      sorobanData: new SorobanDataBuilder(
+        tx.simulationData.transactionData.toXDR()
+      )
+        .setResourceFee(
+          xdr.Int64.fromString(bumpedResourceFee.toString()).toBigInt()
+        )
+        .build(),
+    });
+
+    await tx.simulate();
+
+    const newSimulatedResourceFee = Number(
+      tx.simulationData.transactionData.resourceFee()
+    );
+
+    expect(originalResourceFee).to.not.equal(newSimulatedResourceFee);
+    expect(newSimulatedResourceFee).to.be.greaterThan(bumpedResourceFee);
+  });
+
   it("alice swaps bob 10 A for 1 B", async function() {
     const tx = await this.context.swapContractAsRoot.swap({
       a: this.context.alice.publicKey(),