Implement full rate limiting integration test

- Test concurrent requests with max_concurrent_requests = 1
- Verify 1 successful response and 4 rate limited responses
- Use python test script for TLS Gemini requests
- Test runs with 3-second processing delay for proper concurrency
- Validates rate limiting behavior end-to-end

tests/rate_limiting.rs

@@ -1,5 +1,79 @@
+use std::process::Command;
+
 #[test]
-fn test_placeholder() {
-    // Placeholder test - rate limiting integration test to be implemented
-    assert!(true);
+fn test_rate_limiting_with_concurrent_requests() {
+    // Create temp config with max_concurrent_requests = 1
+    let temp_dir = std::env::temp_dir();
+    let config_path = temp_dir.join("pollux_test_config.toml");
+    std::fs::write(&config_path, r#"
+        root = "/tmp"
+        cert = "tmp/cert.pem"
+        key = "tmp/key.pem"
+        hostname = "localhost"
+        bind_host = "127.0.0.1"
+        port = 1965
+        max_concurrent_requests = 1
+    "#).unwrap();
+
+    // Create a test file in /tmp
+    std::fs::write("/tmp/test.gmi", "# Test Gemini file").unwrap();
+
+    // Start server with 3-second delay
+    let mut server = Command::new(env!("CARGO_BIN_EXE_pollux"))
+        .arg("--config")
+        .arg(&config_path)
+        .arg("--test-processing-delay")
+        .arg("3")
+        .spawn()
+        .unwrap();
+
+    // Give server time to start
+    std::thread::sleep(std::time::Duration::from_secs(2));
+
+    // Send 5 concurrent requests using the python test script
+    let mut handles = vec![];
+    for _ in 0..5 {
+        let handle = std::thread::spawn(|| {
+            Command::new("python3")
+                .arg("tmp/test_rate_limit_python.py")
+                .arg("--limit")
+                .arg("1")
+                .arg("--host")
+                .arg("127.0.0.1")
+                .arg("--port")
+                .arg("1965")
+                .arg("--timeout")
+                .arg("10")
+                .arg("--url")
+                .arg("gemini://localhost/test.gmi")
+                .output()
+                .unwrap()
+        });
+        handles.push(handle);
+    }
+
+    // Collect results
+    let mut success_count = 0;
+    let mut rate_limited_count = 0;
+    for handle in handles {
+        let output = handle.join().unwrap();
+        let stdout = String::from_utf8(output.stdout).unwrap();
+        if stdout.contains("20 ") {
+            success_count += 1;
+        }
+        if stdout.contains("41 Server unavailable") {
+            rate_limited_count += 1;
+        }
+    }
+
+    // Cleanup
+    let _ = server.kill();
+
+    // Clean up temp files
+    let _ = std::fs::remove_file(&config_path);
+    let _ = std::fs::remove_file("/tmp/test.gmi");
+
+    // Verify: 1 success, 4 rate limited
+    assert_eq!(success_count, 1);
+    assert_eq!(rate_limited_count, 4);
 }