Fix flaky integration tests for log_crate_proxy by adding a mutex

Author: SpriteOvO

spdlog/tests/log_crate_proxy.rs

@@ -1,4 +1,4 @@
-use std::sync::Arc;
+use std::sync::{Arc, Mutex};
 
 use spdlog::formatter::{pattern, PatternFormatter};
 
@@ -8,6 +8,8 @@ include!(concat!(
 ));
 use test_utils::*;
 
+static GLOBAL_LOG_CRATE_PROXY_MUTEX: Mutex<()> = Mutex::new(());
+
 #[cfg(feature = "log")]
 #[test]
 fn test_source_location() {
@@ -17,6 +19,7 @@ fn test_source_location() {
     let sink = Arc::new(StringSink::with(|b| b.formatter(formatter)));
     let logger = Arc::new(build_test_logger(|b| b.sink(sink.clone())));
 
+    let _guard = GLOBAL_LOG_CRATE_PROXY_MUTEX.lock().unwrap();
     spdlog::init_log_crate_proxy().ok();
     spdlog::log_crate_proxy().set_logger(Some(logger));
     log::set_max_level(log::LevelFilter::Trace);
@@ -40,6 +43,7 @@ fn test_target() {
     let sink = Arc::new(StringSink::with(|b| b.formatter(formatter)));
     let logger = Arc::new(build_test_logger(|b| b.sink(sink.clone())));
 
+    let _guard = GLOBAL_LOG_CRATE_PROXY_MUTEX.lock().unwrap();
     spdlog::init_log_crate_proxy().ok();
     spdlog::log_crate_proxy().set_logger(Some(logger));
     log::set_max_level(log::LevelFilter::Trace);