Improves the robustness of integration tests

We removed the manual assigned port numbers in two integration tests. That ensures that each integration Test uses it's own Redis Server instance
We used a separate output directory and filename for the rdb file that may get stored during integration testing.

Author: DarthB

tests/integration.rs

@@ -651,11 +651,7 @@ fn test_open_key_with_flags() -> Result<()> {
 
 #[test]
 fn test_expire() -> Result<()> {
-    let port: u16 = 6502;
-    let _guards = vec![start_redis_server_with_module("expire", port)
-        .with_context(|| "failed to start redis server")?];
-    let mut con =
-        get_redis_connection(port).with_context(|| "failed to connect to redis server")?;
+    let mut con = TestConnection::new("expire");
 
     // Create a key without TTL
     redis::cmd("set")
@@ -689,11 +685,7 @@ fn test_expire() -> Result<()> {
 
 #[test]
 fn test_defrag() -> Result<()> {
-    let port: u16 = 6503;
-    let _guards = vec![start_redis_server_with_module("data_type", port)
-        .with_context(|| "failed to start redis server")?];
-    let mut con =
-        get_redis_connection(port).with_context(|| "failed to connect to redis server")?;
+    let mut con = TestConnection::new("data_type");
 
     // Configure active defrag
     redis::cmd("config")

tests/utils.rs

@@ -95,13 +95,34 @@ pub fn start_redis_server_with_module(module_name: &str, port: u16) -> Result<Ch
 
     let module_path = format!("{}", module_path.display());
 
+    let rdb_filename = format!("test-on-port-{}.rdb", port);
+    let rdb_out_dir = std::env::current_dir()?;
+    let rdb_out_dir = rdb_out_dir.join(format!("target/integration-test/instance-p{}", port));
+    if rdb_out_dir.exists() {
+        fs::remove_dir_all(&rdb_out_dir).with_context(|| {
+            format!(
+                "Removing existing rdb output dir: {}",
+                rdb_out_dir.display()
+            )
+        })?;
+    }
+
+    fs::create_dir_all(&rdb_out_dir)
+        .with_context(|| format!("Creating rdb output dir: {}", rdb_out_dir.display()))?;
+
     let args = &[
         "--port",
         &port.to_string(),
         "--loadmodule",
         module_path.as_str(),
         "--enable-debug-command",
         "yes",
+        "--dir",
+        rdb_out_dir
+            .to_str()
+            .expect("RDB output directory path contains invalid UTF-8 characters"),
+        "--dbfilename",
+        rdb_filename.as_str(),
     ];
 
     let redis_server = Command::new("redis-server")