electrsd 0.23.3

Utility to run a regtest electrs process, useful in integration testing environment
Documentation 
[![MIT license](https://img.shields.io/github/license/RCasatta/electrsd)](https://github.com/RCasatta/electrsd/blob/master/LICENSE)
[![Crates](https://img.shields.io/crates/v/electrsd.svg)](https://crates.io/crates/electrsd)

# Electrsd

Utility to run a regtest [electrs](https://github.com/romanz/electrs/) process connected to a given [bitcoind](https://github.com/RCasatta/bitcoind) instance, 
useful in integration testing environment.

```rust
let bitcoind = bitcoind::BitcoinD::new("/usr/local/bin/bitcoind").unwrap();
let electrsd = electrsd::ElectrsD::new("/usr/local/bin/electrs", bitcoind).unwrap();
let header = electrsd.client.block_headers_subscribe().unwrap();
assert_eq!(header.height, 0);
```

## Automatic binaries download

In your project Cargo.toml, activate the following features
```yml
electrsd = { version= "0.23", features = ["bitcoind_23_0", "electrs_0_9_1"] }
```
Then use it:
```rust
let bitcoind_exe = bitcoind::downloaded_exe_path().expect("bitcoind version feature must be enabled");
let bitcoind = bitcoind::BitcoinD::new(bitcoind_exe).unwrap();
let electrs_exe = electrsd::downloaded_exe_path().expect("electrs version feature must be enabled");
let electrsd = electrsd::ElectrsD::new(electrs_exe, bitcoind).unwrap();
```

When the `ELECTRSD_DOWNLOAD_ENDPOINT`/`BITCOIND_DOWNLOAD_ENDPOINT` environment variables are set,
`electrsd`/`bitcoind` will try to download the binaries from the given endpoints.

## Issues with traditional approach

I used integration testing based on external bash script launching needed external processes, there are many issues with this approach like:

* External script may interfere with local development environment https://github.com/rust-bitcoin/rust-bitcoincore-rpc/blob/200fc8247c1896709a673b82a89ca0da5e7aa2ce/integration_test/run.sh#L9
* Use of a single huge test to test everything https://github.com/rust-bitcoin/rust-bitcoincore-rpc/blob/200fc8247c1896709a673b82a89ca0da5e7aa2ce/integration_test/src/main.rs#L122-L203
* If test are separated, a failing test may fail to leave a clean situation, causing other test to fail (because of the initial situation, not a real failure)
* bash script are hard, especially support different OS and versions

## Features

  * electrsd use a temporary directory as db dir
  * A free port is asked to the OS (a very low probability race condition is still possible) 
  * The process is killed when the struct goes out of scope no matter how the test finishes
  * Automatically download `electrs` executable with enabled features. Since there are no official binaries, they are built using the [manual workflow](.github/workflows/build_electrs.yml) under this project. Supported version are:
    * [electrs 0.9.1](https://github.com/romanz/electrs/releases/tag/v0.9.1) (feature=electrs_0_9_1)
    * [electrs 0.8.10](https://github.com/romanz/electrs/releases/tag/v0.8.10) (feature=electrs_0_8_10)
    * [electrs esplora](https://github.com/Blockstream/electrs/tree/a33e97e1a1fc63fa9c20a116bb92579bbf43b254) (feature=esplora_a33e97e1)

Thanks to these features every `#[test]` could easily run isolated with its own environment

## Used by

  * [bdk](https://github.com/bitcoindevkit/bdk)
  * [BEWallet](https://github.com/LeoComandini/BEWallet)
  * [gdk rust](https://github.com/Blockstream/gdk/blob/master/subprojects/gdk_rust/)