Merge bitcoindevkit/bdk#682: Add a custom signer for hardware wallets

138acc3b7d Change `populate_test_db` to not return empty input (wszdexdrf)
d6e1dd1040 Change CI to add test using ledger emulator (wszdexdrf)
76034772cb Add a custom signer for hardware wallets (wszdexdrf)

Pull request description:

  Also adds a new test in CI for building and testing on a virtual
  hardware wallet.

  ### Description

  This PR would enable BDK users to sign transactions using a hardware wallet. It is just the beginning hence there are no complex features, but I hope not for long.
  I have added a test in CI for building a ledger emulator and running the new test on it. The test is similar to the one on bitcoindevkit/rust-hwi.

  ### Notes to the reviewers
  The PR is incomplete (and wouldn't work, as the rust-hwi in `cargo.toml` is pointing to a local crate, temporarily) as a small change is required in rust-hwi (https://github.com/bitcoindevkit/rust-hwi/pull/42).

  ### Checklists

  #### All Submissions:

  * [x] I've signed all my commits
  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk/blob/master/CONTRIBUTING.md)
  * [x] I ran `cargo fmt` and `cargo clippy` before committing

  #### New Features:

  * [x] I've added tests for the new feature
  * [x] I've added docs for the new feature
  * [x] I've updated `CHANGELOG.md`

ACKs for top commit:
  afilini:
    ACK 138acc3b7d

Tree-SHA512: 54337f06247829242b4dc60f733346173d957de8e9f8b80beb91304d679cfb4e0e4db722c967469265a5b6ede2bd641ba5c089760391c671995dc30de37897de

src/wallet/mod.rs

@@ -48,6 +48,9 @@ pub(crate) mod utils;
 #[cfg_attr(docsrs, doc(cfg(feature = "verify")))]
 pub mod verify;
 
+#[cfg(feature = "hardware-signer")]
+pub mod hardwaresigner;
+
 pub use utils::IsDust;
 
 #[allow(deprecated)]
@@ -5466,4 +5469,33 @@ pub(crate) mod test {
         // ...and checking that everything is fine
         assert_fee_rate!(psbt, details.fee.unwrap_or(0), fee_rate);
     }
+
+    #[cfg(feature = "test-hardware-signer")]
+    #[test]
+    fn test_create_signer() {
+        use crate::wallet::hardwaresigner::HWISigner;
+        use hwi::types::HWIChain;
+        use hwi::HWIClient;
+
+        let devices = HWIClient::enumerate().unwrap();
+        let device = devices.first().expect("No devices found");
+        let client = HWIClient::get_client(device, true, HWIChain::Regtest).unwrap();
+        let descriptors = client.get_descriptors(None).unwrap();
+        let custom_signer = HWISigner::from_device(device, HWIChain::Regtest).unwrap();
+
+        let (mut wallet, _, _) = get_funded_wallet(&descriptors.internal[0]);
+        wallet.add_signer(
+            KeychainKind::External,
+            SignerOrdering(200),
+            Arc::new(custom_signer),
+        );
+
+        let addr = wallet.get_address(LastUnused).unwrap();
+        let mut builder = wallet.build_tx();
+        builder.drain_to(addr.script_pubkey()).drain_wallet();
+        let (mut psbt, _) = builder.finish().unwrap();
+
+        let finalized = wallet.sign(&mut psbt, Default::default()).unwrap();
+        assert!(finalized);
+    }
 }