feat: add updateInputWithDescriptor util

This util function allows working with native UtxoPsbt

Issue: BTC-1451

Author: OttoAllmendinger

packages/wasm-miniscript/test/psbt.ts

@@ -4,7 +4,7 @@ import { getPsbtFixtures } from "./psbtFixtures";
 import { Descriptor, Psbt } from "../js";
 
 import { getDescriptorForScriptType } from "./descriptorUtil";
-import { toUtxoPsbt, toWrappedPsbt } from "./psbt.util";
+import { toUtxoPsbt, toWrappedPsbt, updateInputWithDescriptor } from "./psbt.util";
 
 const rootWalletKeys = new utxolib.bitgo.RootWalletKeys(utxolib.testutil.getKeyTriple("wasm"));
 
@@ -25,11 +25,12 @@ function describeUpdateInputWithDescriptor(
     throw new Error("Could not find fullsigned fixture");
   }
 
-  describe("updateInputWithDescriptor", function () {
+  const descriptorStr = getDescriptorForScriptType(rootWalletKeys, scriptType, "internal");
+  const index = 0;
+  const descriptor = Descriptor.fromString(descriptorStr, "derivable");
+
+  describe("Wrapped PSBT updateInputWithDescriptor", function () {
     it("should update the input with the descriptor", function () {
-      const descriptorStr = getDescriptorForScriptType(rootWalletKeys, scriptType, "internal");
-      const index = 0;
-      const descriptor = Descriptor.fromString(descriptorStr, "derivable");
       const wrappedPsbt = toWrappedPsbt(psbt);
       wrappedPsbt.updateInputWithDescriptor(0, descriptor.atDerivationIndex(index));
       const updatedPsbt = toUtxoPsbt(wrappedPsbt);
@@ -47,6 +48,21 @@ function describeUpdateInputWithDescriptor(
       );
     });
   });
+
+  describe("updateInputWithDescriptor util", function () {
+    it("should update the input with the descriptor", function () {
+      const cloned = psbt.clone();
+      updateInputWithDescriptor(cloned, 0, descriptor.atDerivationIndex(index));
+      cloned.signAllInputsHD(rootWalletKeys.triple[0]);
+      cloned.signAllInputsHD(rootWalletKeys.triple[2]);
+      cloned.finalizeAllInputs();
+
+      assertEqualBuffer(
+        fullSignedFixture.psbt.clone().finalizeAllInputs().extractTransaction().toBuffer(),
+        cloned.extractTransaction().toBuffer(),
+      );
+    });
+  });
 }
 
 fixtures.forEach(({ psbt, scriptType, stage }) => {

packages/wasm-miniscript/test/psbt.util.ts

@@ -1,5 +1,5 @@
 import * as utxolib from "@bitgo/utxo-lib";
-import { Psbt } from "../js";
+import { Descriptor, Psbt } from "../js";
 
 export function toWrappedPsbt(psbt: utxolib.bitgo.UtxoPsbt | Buffer | Uint8Array) {
   if (psbt instanceof utxolib.bitgo.UtxoPsbt) {
@@ -21,4 +21,14 @@ export function toUtxoPsbt(psbt: Psbt | Buffer | Uint8Array) {
     });
   }
   throw new Error("Invalid input");
-}
+}
+
+export function updateInputWithDescriptor(
+  psbt: utxolib.bitgo.UtxoPsbt,
+  inputIndex: number,
+  descriptor: Descriptor,
+) {
+  const wrappedPsbt = toWrappedPsbt(psbt);
+  wrappedPsbt.updateInputWithDescriptor(inputIndex, descriptor);
+  psbt.data.inputs[inputIndex] = toUtxoPsbt(wrappedPsbt).data.inputs[inputIndex];
+}