refactor(tests-async): unify duplicated tokio runtime bridges

11 downloader/installer integration-test files each redefined an
identical current_thread `run()` helper to block on async code. Extract
one shared multi_thread Runtime into tests/common/async_runtime.rs so
concurrent #[test] threads can all block_on it, matching the direction
item 7 (top-level Runtime) will take in production code.

1 files changed, 23 insertions, 0 deletions

diff --git a/crates/shirabe/tests/common/async_runtime.rs b/crates/shirabe/tests/common/async_runtime.rs
new file mode 100644
index 00000000..e047315a
--- /dev/null
+++ b/crates/shirabe/tests/common/async_runtime.rs
@@ -0,0 +1,23 @@
+//! Shared tokio runtime bridge for integration tests.
+//!
+//! `cargo test` runs `#[test]` fns concurrently on separate OS threads, so a per-call
+//! `current_thread` Runtime would need one instance per caller. Instead this holds a single
+//! process-wide `multi_thread` Runtime that tolerates concurrent `block_on()` callers, and every
+//! test bridges into async code through it.
+//!
+//! Included into each integration-test binary via
+//! `#[path = "../common/async_runtime.rs"] mod async_runtime;`.
+#![allow(dead_code)]
+
+use std::sync::LazyLock;
+
+static RUNTIME: LazyLock<tokio::runtime::Runtime> = LazyLock::new(|| {
+    tokio::runtime::Builder::new_multi_thread()
+        .enable_all()
+        .build()
+        .unwrap()
+});
+
+pub fn run<F: std::future::Future>(future: F) -> F::Output {
+    RUNTIME.block_on(future)
+}