diff --git a/network-node/src/lib.rs b/network-node/src/lib.rs
index 8e98537..bcfc4ca 100644
--- a/network-node/src/lib.rs
+++ b/network-node/src/lib.rs
@@ -25,6 +25,7 @@ pub fn health_status(environment: Option<String>) -> HealthResponse {
 mod tests {
     use super::*;
 
+    // Happy path tests
     #[test]
     fn health_status_with_none_env() {
         let resp = health_status(None);
@@ -42,4 +43,167 @@ mod tests {
         assert_eq!(resp.version, env!("CARGO_PKG_VERSION"));
         assert_eq!(resp.environment, Some("test-env".to_string()));
     }
+
+    // Test all required fields are present
+    #[test]
+    fn health_response_has_all_required_fields() {
+        let resp = health_status(None);
+
+        // Status field
+        assert!(!resp.status.is_empty(), "Status should not be empty");
+        assert_eq!(resp.status, "ok");
+
+        // Service name field
+        assert!(
+            !resp.service_name.is_empty(),
+            "Service name should not be empty"
+        );
+        assert_eq!(resp.service_name, "axionvera-network-node");
+
+        // Version field
+        assert!(!resp.version.is_empty(), "Version should not be empty");
+        assert_eq!(resp.version, env!("CARGO_PKG_VERSION"));
+
+        // Environment field (optional but should be present in struct)
+        assert_eq!(resp.environment, None);
+    }
+
+    // Test with various environment values
+    #[test]
+    fn health_status_with_production_env() {
+        let resp = health_status(Some("production".to_string()));
+        assert_eq!(resp.environment, Some("production".to_string()));
+        assert_eq!(resp.status, "ok");
+    }
+
+    #[test]
+    fn health_status_with_staging_env() {
+        let resp = health_status(Some("staging".to_string()));
+        assert_eq!(resp.environment, Some("staging".to_string()));
+        assert_eq!(resp.status, "ok");
+    }
+
+    #[test]
+    fn health_status_with_development_env() {
+        let resp = health_status(Some("development".to_string()));
+        assert_eq!(resp.environment, Some("development".to_string()));
+        assert_eq!(resp.status, "ok");
+    }
+
+    // Test serialization support
+    #[test]
+    fn health_response_serializes_correctly() {
+        let resp = health_status(Some("test-env".to_string()));
+        let json = serde_json::to_string(&resp).expect("Failed to serialize");
+
+        assert!(json.contains("\"status\":\"ok\""));
+        assert!(json.contains("\"service_name\":\"axionvera-network-node\""));
+        assert!(json.contains("\"version\":"));
+        assert!(json.contains("\"environment\":\"test-env\""));
+    }
+
+    #[test]
+    fn health_response_serializes_without_environment() {
+        let resp = health_status(None);
+        let json = serde_json::to_string(&resp).expect("Failed to serialize");
+
+        assert!(json.contains("\"status\":\"ok\""));
+        assert!(json.contains("\"service_name\":\"axionvera-network-node\""));
+        assert!(json.contains("\"version\":"));
+        assert!(json.contains("\"environment\":null"));
+    }
+
+    // Test deserialization support
+    #[test]
+    fn health_response_deserializes_correctly() {
+        let json = r#"{"status":"ok","service_name":"axionvera-network-node","version":"0.1.0","environment":"test-env"}"#;
+        let resp: HealthResponse = serde_json::from_str(json).expect("Failed to deserialize");
+
+        assert_eq!(resp.status, "ok");
+        assert_eq!(resp.service_name, "axionvera-network-node");
+        assert_eq!(resp.version, "0.1.0");
+        assert_eq!(resp.environment, Some("test-env".to_string()));
+    }
+
+    #[test]
+    fn health_response_deserializes_without_environment() {
+        let json = r#"{"status":"ok","service_name":"axionvera-network-node","version":"0.1.0","environment":null}"#;
+        let resp: HealthResponse = serde_json::from_str(json).expect("Failed to deserialize");
+
+        assert_eq!(resp.status, "ok");
+        assert_eq!(resp.service_name, "axionvera-network-node");
+        assert_eq!(resp.version, "0.1.0");
+        assert_eq!(resp.environment, None);
+    }
+
+    // Test response consistency
+    #[test]
+    fn health_response_maintains_consistency() {
+        let resp1 = health_status(Some("env1".to_string()));
+        let resp2 = health_status(Some("env1".to_string()));
+
+        assert_eq!(resp1.status, resp2.status);
+        assert_eq!(resp1.service_name, resp2.service_name);
+        assert_eq!(resp1.version, resp2.version);
+        assert_eq!(resp1.environment, resp2.environment);
+    }
+
+    // Test response equality
+    #[test]
+    fn health_response_equality() {
+        let resp1 = HealthResponse {
+            status: "ok".to_string(),
+            service_name: "axionvera-network-node".to_string(),
+            version: "0.1.0".to_string(),
+            environment: Some("test".to_string()),
+        };
+
+        let resp2 = HealthResponse {
+            status: "ok".to_string(),
+            service_name: "axionvera-network-node".to_string(),
+            version: "0.1.0".to_string(),
+            environment: Some("test".to_string()),
+        };
+
+        assert_eq!(resp1, resp2);
+    }
+
+    // Test empty string environment
+    #[test]
+    fn health_status_with_empty_string_env() {
+        let resp = health_status(Some(String::new()));
+        assert_eq!(resp.status, "ok");
+        assert_eq!(resp.environment, Some(String::new()));
+    }
+
+    // Test long environment string
+    #[test]
+    fn health_status_with_long_env_string() {
+        let long_env = "production-us-west-2-cluster-a".to_string();
+        let resp = health_status(Some(long_env.clone()));
+        assert_eq!(resp.environment, Some(long_env));
+        assert_eq!(resp.status, "ok");
+    }
+
+    // Test struct derives
+    #[test]
+    fn health_response_debug_format() {
+        let resp = health_status(Some("test".to_string()));
+        let debug_str = format!("{:?}", resp);
+
+        assert!(debug_str.contains("HealthResponse"));
+        assert!(debug_str.contains("status"));
+        assert!(debug_str.contains("service_name"));
+        assert!(debug_str.contains("version"));
+        assert!(debug_str.contains("environment"));
+    }
+
+    #[test]
+    fn health_response_clone() {
+        let resp1 = health_status(Some("test".to_string()));
+        let resp2 = resp1.clone();
+
+        assert_eq!(resp1, resp2);
+        assert_eq!(resp1.status, resp2.status);
+    }
 }