feat(wallet): special-case descriptor for single-guardian instances

devimint/src/main.rs

@@ -354,6 +354,21 @@ async fn cli_tests(dev_fed: DevFed) -> Result<()> {
         .state();
     anyhow::ensure!(invoice_status == tonic_lnd::lnrpc::invoice::InvoiceState::Settled);
 
+    // # Test the correct descriptor is used
+    let config = cmd!(fed, "config").out_json().await?;
+    let guardian_count = config["global"]["api_endpoints"].as_object().unwrap().len();
+    let descriptor = config["modules"]["2"]["peg_in_descriptor"]
+        .as_str()
+        .unwrap()
+        .to_owned();
+
+    info!("Testing generated descriptor for {guardian_count} guardian federation");
+    if guardian_count == 1 {
+        assert!(descriptor.contains("wpkh("));
+    } else {
+        assert!(descriptor.contains("wsh(sortedmulti("));
+    }
+
     // # Client tests
     info!("Testing Client");
     // ## reissue e-cash

modules/fedimint-wallet-common/src/config.rs

@@ -7,7 +7,7 @@ use fedimint_core::encoding::{Decodable, Encodable};
 use fedimint_core::module::__reexports::serde_json;
 use fedimint_core::util::SafeUrl;
 use fedimint_core::{plugin_types_trait_impl_config, Feerate, PeerId};
-use miniscript::descriptor::Wsh;
+use miniscript::descriptor::{Wpkh, Wsh};
 use secp256k1::SecretKey;
 use serde::{Deserialize, Serialize};
 
@@ -150,9 +150,21 @@ impl WalletConfig {
         bitcoin_rpc: BitcoinRpcConfig,
         client_default_bitcoin_rpc: BitcoinRpcConfig,
     ) -> Self {
-        let peg_in_descriptor = PegInDescriptor::Wsh(
-            Wsh::new_sortedmulti(threshold, pubkeys.values().copied().collect()).unwrap(),
-        );
+        let peg_in_descriptor = if pubkeys.len() == 1 {
+            PegInDescriptor::Wpkh(
+                Wpkh::new(
+                    *pubkeys
+                        .values()
+                        .next()
+                        .expect("there is exactly one pub key"),
+                )
+                .expect("Our key type is always compressed"),
+            )
+        } else {
+            PegInDescriptor::Wsh(
+                Wsh::new_sortedmulti(threshold, pubkeys.values().copied().collect()).unwrap(),
+            )
+        };
 
         Self {
             local: WalletConfigLocal { bitcoin_rpc },

nix/flakebox.nix

@@ -338,6 +338,12 @@ rec {
     buildPhaseCargoCommand = "patchShebangs ./scripts ; ./scripts/tests/devimint-cli-test.sh";
   };
 
+  devimintCliTestSingle = craneLibTests.mkCargoDerivation {
+      pname = "${commonCliTestArgs.pname}-cli";
+      cargoArtifacts = workspaceBuild;
+      buildPhaseCargoCommand = "patchShebangs ./scripts ; ./scripts/tests/devimint-cli-test-single.sh";
+    };
+
   cliLoadTestToolTest = craneLibTests.mkCargoDerivation {
     pname = "${commonCliTestArgs.pname}-cli";
     cargoArtifacts = workspaceBuild;

scripts/tests/devimint-cli-test-single.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+# Runs a CLI-based integration test
+
+set -euo pipefail
+export RUST_LOG="${RUST_LOG:-info}"
+
+source scripts/_common.sh
+build_workspace
+add_target_dir_to_path
+make_fm_test_marker
+
+devimint -n 1 cli-tests

scripts/tests/test-ci-all.sh

@@ -63,6 +63,11 @@ function devimint_cli_test() {
 }
 export -f devimint_cli_test
 
+function devimint_cli_test_single() {
+  fm-run-test "${FUNCNAME[0]}" ./scripts/tests/devimint-cli-test-single.sh
+}
+export -f devimint_cli_test_single
+
 function load_test_tool_test() {
   fm-run-test "${FUNCNAME[0]}" ./scripts/tests/load-test-tool-test.sh
 }
@@ -126,6 +131,7 @@ if parallel \
   lightning_reconnect_test \
   gateway_reboot_test \
   devimint_cli_test \
+  devimint_cli_test_single \
   load_test_tool_test \
   recoverytool_tests ; then
   >&2 echo "All tests successful"