fix: use serial_test for env var tests and improve MySQL readiness check (#213)

- Added serial_test dependency for tests that modify environment variables
- Marked env var tests with #[serial] to prevent race conditions
- Changed MySQL readiness check to use TCP (127.0.0.1) instead of Unix socket
- Require 2 consecutive successful connections before declaring ready
- Updated test to also use TCP connection for consistency

Author: joshrotenberg

Cargo.toml

@@ -81,6 +81,7 @@ tempfile = "3.0"
 which = "8.0"
 serde_json = "1.0"
 proptest = "1.6"
+serial_test = "3.3.1"
 
 [[example]]
 name = "basic_usage"

src/template/database/mysql.rs

@@ -319,15 +319,19 @@ impl Template for MysqlTemplate {
         let check_interval = Duration::from_millis(1000);
 
         timeout(wait_timeout, async {
+            let mut consecutive_successes = 0;
             loop {
                 // Check if container is running - keep retrying if not yet started
                 // Don't fail immediately as the container may still be starting up
                 if !self.is_running().await.unwrap_or(false) {
+                    consecutive_successes = 0;
                     sleep(check_interval).await;
                     continue;
                 }
 
-                // Try to connect to MySQL using mysqladmin
+                // Try to connect to MySQL using the mysql client with an actual query
+                // Use 127.0.0.1 instead of localhost to force TCP connection
+                // (localhost uses Unix socket which may not be ready even when TCP is)
                 let password = self
                     .config
                     .env
@@ -338,23 +342,31 @@ impl Template for MysqlTemplate {
 
                 let password_arg = format!("-p{}", password);
                 let check_cmd = vec![
-                    "mysqladmin",
+                    "mysql",
                     "-h",
-                    "localhost",
+                    "127.0.0.1",
                     "-u",
                     "root",
                     &password_arg,
-                    "ping",
+                    "-e",
+                    "SELECT 1",
                 ];
 
                 // Execute readiness check
                 if let Ok(result) = self.exec(check_cmd).await {
-                    // mysqladmin ping returns "mysqld is alive" on success
-                    if result.stdout.contains("mysqld is alive") {
-                        return Ok(());
+                    // If we got output containing '1', MySQL responded successfully
+                    if result.stdout.contains('1') {
+                        consecutive_successes += 1;
+                        // Require 2 consecutive successes to ensure stability
+                        if consecutive_successes >= 2 {
+                            return Ok(());
+                        }
+                        sleep(Duration::from_millis(500)).await;
+                        continue;
                     }
                 }
 
+                consecutive_successes = 0;
                 sleep(check_interval).await;
             }
         })

src/template/redis/cluster.rs

@@ -812,6 +812,7 @@ impl RedisClusterConnection {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use serial_test::serial;
 
     #[test]
     fn test_redis_cluster_template_basic() {
@@ -899,6 +900,7 @@ mod tests {
     }
 
     #[test]
+    #[serial]
     fn test_redis_cluster_from_env_defaults() {
         // Clear any existing env vars to ensure defaults are used
         std::env::remove_var("REDIS_CLUSTER_PORT_BASE");
@@ -914,6 +916,7 @@ mod tests {
     }
 
     #[test]
+    #[serial]
     fn test_redis_cluster_from_env_with_vars() {
         std::env::set_var("REDIS_CLUSTER_PORT_BASE", "8000");
         std::env::set_var("REDIS_CLUSTER_NUM_MASTERS", "6");

tests/database_template_integration.rs

@@ -228,10 +228,12 @@ mod database_template_tests {
             assert!(conn.url().contains("testdb"));
             assert!(conn.url().contains("testuser"));
 
-            // Execute a simple query
+            // Execute a simple query (use 127.0.0.1 to force TCP, matching readiness check)
             let result = mysql
                 .exec(vec![
                     "mysql",
+                    "-h",
+                    "127.0.0.1",
                     "-u",
                     "root",
                     "-prootpass",