Add backon retry to tests

Hopefully fix the following error I've been seeing in CI for downloading
test-assets

---- test_19 stdout ----
Fetching file out.squashfs ...[/home/runner/.cargo/git/checkouts/test-assets-af055f640a5e3329/ebe2e7d/src/lib.rs:137:5] &tfile.url = "https://wcampbell.dev/squashfs/testing/test_19/out.squashfs"
thread 'test_19' panicked at backhand-test/tests/test.rs:66:68:
called `Result::unwrap()` on an `Err` value: Io(Custom { kind: UnexpectedEof, error: "peer closed connection without sending TLS close_notify: https://docs.rs/rustls/latest/rustls/manual/_03_howto/index.html#unexpected-eof" })
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

backhand-test/Cargo.toml

@@ -16,6 +16,7 @@ libdeflater = "1.21.0"
 env_logger = "0.11.5"
 tracing-subscriber = { version = "0.3.18", features = ["env-filter", "fmt"] }
 nix = { version = "0.28.0", default-features = false, features = ["fs"] }
+backon = "1.2.0"
 
 [lib]
 bench = false

backhand-test/tests/test.rs

@@ -1,10 +1,14 @@
 mod common;
+use std::error::Error;
 use std::fs::File;
 use std::io::{BufReader, BufWriter};
+use std::time::Duration;
 
 use assert_cmd::prelude::*;
 use assert_cmd::Command;
 use backhand::{FilesystemReader, FilesystemWriter};
+use backon::BlockingRetryable;
+use backon::ExponentialBuilder;
 use common::{test_bin_unsquashfs, test_squashfs_tools_unsquashfs};
 use tempfile::tempdir;
 use test_assets::TestAssetDef;
@@ -54,6 +58,13 @@ fn full_test(
  full_test_inner(assets_defs, filepath, test_path, offset, verify, assert_success, true)
 }
 
+fn download(assets_defs: &[TestAssetDef], test_path: &str) -> Result<(), Box<dyn Error>> {
+ if test_assets::download_test_files(assets_defs, test_path, true).is_err() {
+ return Err("falied to download".into());
+ }
+ Ok(())
+}
+
 fn full_test_inner(
  assets_defs: &[TestAssetDef],
  filepath: &str,
@@ -63,7 +74,9 @@ fn full_test_inner(
  assert_success: bool,
  run_squashfs_tools_unsquashfs: bool,
 ) {
- test_assets::download_test_files(assets_defs, test_path, true).unwrap();
+ let strategy = ExponentialBuilder::default().with_max_delay(Duration::from_secs(60));
+
+ let _result = (|| download(assets_defs, test_path)).retry(strategy).call().unwrap();
 
  let og_path = format!("{test_path}/{filepath}");
  let new_path = format!("{test_path}/bytes.squashfs");