Test bitcoin-serai

Also resolves a few rough edges.

coins/bitcoin/tests/runner.rs

@@ -0,0 +1,44 @@
+use bitcoin_serai::rpc::Rpc;
+
+use tokio::sync::Mutex;
+
+lazy_static::lazy_static! {
+  pub static ref SEQUENTIAL: Mutex<()> = Mutex::new(());
+}
+
+#[allow(dead_code)]
+pub(crate) async fn rpc() -> Rpc {
+  let rpc = Rpc::new("http://serai:seraidex@127.0.0.1:18443".to_string()).await.unwrap();
+
+  // If this node has already been interacted with, clear its chain
+  if rpc.get_latest_block_number().await.unwrap() > 0 {
+    rpc
+      .rpc_call(
+        "invalidateblock",
+        serde_json::json!([hex::encode(rpc.get_block_hash(1).await.unwrap())]),
+      )
+      .await
+      .unwrap()
+  }
+
+  rpc
+}
+
+#[macro_export]
+macro_rules! async_sequential {
+  ($(async fn $name: ident() $body: block)*) => {
+    $(
+      #[tokio::test]
+      async fn $name() {
+        let guard = runner::SEQUENTIAL.lock().await;
+        let local = tokio::task::LocalSet::new();
+        local.run_until(async move {
+          if let Err(err) = tokio::task::spawn_local(async move { $body }).await {
+            drop(guard);
+            Err(err).unwrap()
+          }
+        }).await;
+      }
+    )*
+  }
+}