feat(abstract-utxo): add support for taproot descriptors in findDescriptors

Issue: BTC-1786

Author: OttoAllmendinger

modules/abstract-utxo/src/core/descriptor/psbt/findDescriptors.ts

@@ -40,7 +40,7 @@ function findDescriptorForDerivationIndex(
 function getDerivationIndexFromPath(path: string): number {
   const indexStr = path.split('/').pop();
   if (!indexStr) {
-    throw new Error('Invalid derivation path');
+    throw new Error(`Invalid derivation path ${path}`);
   }
   const index = parseInt(indexStr, 10);
   if (index.toString() !== indexStr) {
@@ -84,14 +84,21 @@ export function findDescriptorForInput(
   if (!script) {
     throw new Error('Missing script');
   }
-  if (!input.bip32Derivation) {
-    throw new Error('Missing derivation paths');
+  if (input.bip32Derivation !== undefined) {
+    return findDescriptorForAnyDerivationPath(
+      script,
+      input.bip32Derivation.map((v) => v.path),
+      descriptorMap
+    );
   }
-  return findDescriptorForAnyDerivationPath(
-    script,
-    input.bip32Derivation.map((v) => v.path),
-    descriptorMap
-  );
+  if (input.tapBip32Derivation !== undefined) {
+    return findDescriptorForAnyDerivationPath(
+      script,
+      input.tapBip32Derivation.filter((v) => v.path !== '' && v.path !== 'm').map((v) => v.path),
+      descriptorMap
+    );
+  }
+  throw new Error('Missing derivation path');
 }
 
 /**

modules/abstract-utxo/test/core/descriptor/psbt/findDescriptors.ts

@@ -1,38 +1,43 @@
 import * as assert from 'assert';
 
-import { getDefaultXPubs, getDescriptor } from '../descriptor.utils';
+import { DescriptorTemplate, getDefaultXPubs, getDescriptor } from '../descriptor.utils';
 import { findDescriptorForInput, findDescriptorForOutput } from '../../../../src/core/descriptor/psbt/findDescriptors';
 
 import { mockPsbt } from './mock.utils';
 
-describe('parsePsbt', function () {
-  const descriptorA = getDescriptor('Wsh2Of3', getDefaultXPubs('a'));
-  const descriptorB = getDescriptor('Wsh2Of3', getDefaultXPubs('b'));
-  const descriptorMap = new Map([
-    ['a', descriptorA],
-    ['b', descriptorB],
-  ]);
+function describeWithTemplates(tA: DescriptorTemplate, tB: DescriptorTemplate) {
+  describe(`parsePsbt [${tA},${tB}]`, function () {
+    const descriptorA = getDescriptor(tA, getDefaultXPubs('a'));
+    const descriptorB = getDescriptor(tB, getDefaultXPubs('b'));
+    const descriptorMap = new Map([
+      ['a', descriptorA],
+      ['b', descriptorB],
+    ]);
 
-  it('finds descriptors for PSBT inputs/outputs', function () {
-    const psbt = mockPsbt(
-      [
-        { descriptor: descriptorA, index: 0 },
-        { descriptor: descriptorB, index: 1, id: { vout: 1 } },
-      ],
-      [{ descriptor: descriptorA, index: 2, value: BigInt(1e6) }]
-    );
+    it('finds descriptors for PSBT inputs/outputs', function () {
+      const psbt = mockPsbt(
+        [
+          { descriptor: descriptorA, index: 0 },
+          { descriptor: descriptorB, index: 1, id: { vout: 1 } },
+        ],
+        [{ descriptor: descriptorA, index: 2, value: BigInt(1e6) }]
+      );
 
-    assert.deepStrictEqual(findDescriptorForInput(psbt.data.inputs[0], descriptorMap), {
-      descriptor: descriptorA,
-      index: 0,
-    });
-    assert.deepStrictEqual(findDescriptorForInput(psbt.data.inputs[1], descriptorMap), {
-      descriptor: descriptorB,
-      index: 1,
-    });
-    assert.deepStrictEqual(findDescriptorForOutput(psbt.txOutputs[0].script, psbt.data.outputs[0], descriptorMap), {
-      descriptor: descriptorA,
-      index: 2,
+      assert.deepStrictEqual(findDescriptorForInput(psbt.data.inputs[0], descriptorMap), {
+        descriptor: descriptorA,
+        index: 0,
+      });
+      assert.deepStrictEqual(findDescriptorForInput(psbt.data.inputs[1], descriptorMap), {
+        descriptor: descriptorB,
+        index: 1,
+      });
+      assert.deepStrictEqual(findDescriptorForOutput(psbt.txOutputs[0].script, psbt.data.outputs[0], descriptorMap), {
+        descriptor: descriptorA,
+        index: 2,
+      });
     });
   });
-});
+}
+
+describeWithTemplates('Wsh2Of3', 'Wsh2Of3');
+describeWithTemplates('Wsh2Of3', 'Tr2Of3-NoKeyPath');