itest: expand testAssetBalances to check PrevId selection functionality

itest/assets_test.go

@@ -623,11 +623,19 @@ func testMintBatchAndTransfer(t *harnessTest) {
 	require.True(t.t, proto.Equal(originalBatch, afterBatch))
 }
 
-// testAssetBalances tests the balance retrieval functionality for issued
-// assets. The function mints two batches of assets and asserts if the tapcli
-// `assets balance` returns the correct balances. It then funds a vPSBT, putting
-// a lease on one of the two batches. It then asserts whether the endpoint still
-// returns the correct balances, taking into account the `include_leased` flag.
+// testAssetBalances validates the balance retrieval and virtual PSBT funding
+// functionality for issued assets. The test performs the following steps:
+//  1. Mints two batches of assets and verifies that the tapcli
+//     `assets balance` returns the correct balances.
+//  2. Tests funding a vPSBT, putting a lease on one of the two batches, with
+//     the `FundVirtualPsbt` RPC for various scenarios:
+//     - Fails if the Inputs field contains a nil Outpoint.
+//     - Fails if the Inputs field contains an invalid Outpoint.
+//     - Succeeds if a valid Outpoint is provided in the Inputs field.
+//     - Succeeds if the Inputs field is not provided at all, using asset
+//     coin selection instead.
+//  3. Ensures that leased assets are reflected correctly in the balance
+//     retrieval, with and without the `include_leased` flag.
 func testAssetBalances(t *harnessTest) {
 	ctxb := context.Background()
 	ctxt, cancel := context.WithTimeout(ctxb, defaultWaitTimeout)
@@ -650,6 +658,8 @@ func testAssetBalances(t *harnessTest) {
 
 	var (
 		targetAssetGenesis = targetAsset.AssetGenesis
+		assetId            = targetAssetGenesis.AssetId
+		scriptKey          = targetAsset.ScriptKey
 		aliceTapd          = t.tapd
 		bobLnd             = t.lndHarness.Bob
 	)
@@ -673,6 +683,86 @@ func testAssetBalances(t *harnessTest) {
 	recipients := map[string]uint64{
 		bobAddr.Encoded: bobAddr.Amount,
 	}
+	out, err := wire.NewOutPointFromString(
+		targetAsset.ChainAnchor.AnchorOutpoint,
+	)
+	require.NoError(t.t, err)
+
+	// 1. Fail if Inputs are provided but Outpoint is nil.
+	emptyOutpointPrevId := &wrpc.PrevId{
+		Outpoint:  nil,
+		Id:        assetId,
+		ScriptKey: scriptKey,
+	}
+	_, err = aliceTapd.FundVirtualPsbt(
+		ctxt, &wrpc.FundVirtualPsbtRequest{
+			Template: &wrpc.FundVirtualPsbtRequest_Raw{
+				Raw: &wrpc.TxTemplate{
+					Recipients: recipients,
+					Inputs: []*wrpc.PrevId{
+						emptyOutpointPrevId,
+					},
+				},
+			},
+		},
+	)
+	require.Error(t.t, err)
+	require.Contains(t.t, err.Error(), "index 0 has a nil Outpoint")
+
+	// 2. Fail if Inputs contain an invalid Outpoint.
+	invalidTxidPrevId := &wrpc.PrevId{
+		Outpoint: &taprpc.OutPoint{
+			Txid:        []byte("invalid_txid"),
+			OutputIndex: 0,
+		},
+		Id:        assetId,
+		ScriptKey: scriptKey,
+	}
+	_, err = aliceTapd.FundVirtualPsbt(
+		ctxt, &wrpc.FundVirtualPsbtRequest{
+			Template: &wrpc.FundVirtualPsbtRequest_Raw{
+				Raw: &wrpc.TxTemplate{
+					Recipients: recipients,
+					Inputs: []*wrpc.PrevId{
+						invalidTxidPrevId,
+					},
+				},
+			},
+		},
+	)
+	require.Error(t.t, err)
+	require.Contains(t.t, err.Error(), "invalid Txid length")
+
+	// 3. Succeed if a valid Outpoint is provided.
+	validOutpointPrevId := &wrpc.PrevId{
+		Outpoint: &taprpc.OutPoint{
+			Txid:        out.Hash.CloneBytes(),
+			OutputIndex: out.Index,
+		},
+		Id:        assetId,
+		ScriptKey: scriptKey,
+	}
+	_, err = aliceTapd.FundVirtualPsbt(
+		ctxt, &wrpc.FundVirtualPsbtRequest{
+			Template: &wrpc.FundVirtualPsbtRequest_Raw{
+				Raw: &wrpc.TxTemplate{
+					Recipients: recipients,
+					Inputs: []*wrpc.PrevId{
+						validOutpointPrevId,
+					},
+				},
+			},
+		},
+	)
+	require.NoError(t.t, err)
+
+	// 4. Succeed if no Inputs are provided.
+	// Unlock the input so that it can be spent again.
+	_, err = aliceTapd.RemoveUTXOLease(ctxb, &wrpc.RemoveUTXOLeaseRequest{
+		Outpoint: validOutpointPrevId.Outpoint,
+	})
+	require.NoError(t.t, err)
+
 	_, err = aliceTapd.FundVirtualPsbt(
 		ctxt, &wrpc.FundVirtualPsbtRequest{
 			Template: &wrpc.FundVirtualPsbtRequest_Raw{