Implement unit tests for server functionality

Added unit tests for server initialization and listener binding.

Author: MikAoJk

src/main.rs

@@ -32,3 +32,58 @@ fn main() {
     }
 }
 
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::net::TcpListener;
+
+    struct MockEnvVars {
+        pub databse_url: String,
+        pub server_adress_and_port: String,
+    }
+
+    fn mock_get_environment_variables() -> MockEnvVars {
+        MockEnvVars {
+            databse_url: "postgres://localhost/test".to_string(),
+            server_adress_and_port: "127.0.0.1:8080".to_string(),
+        }
+    }
+
+    fn mock_create_database_client(_url: String) -> Result<(), &'static str> {
+        Ok(())
+    }
+
+    fn mock_set_init_database_table(_client: Result<(), &'static str>) -> Result<(), &'static str> {
+        Ok(())
+    }
+
+    #[test]
+    fn test_server_initialization_success() {
+        let env = mock_get_environment_variables();
+        let client = mock_create_database_client(env.databse_url.clone());
+        let db_init_result = mock_set_init_database_table(client);
+
+        assert!(db_init_result.is_ok());
+    }
+
+    #[test]
+    fn test_server_initialization_failure() {
+
+        fn failing_create_database_client(_url: String) -> Result<(), &'static str> {
+            Err("connection failed")
+        }
+
+        let env = mock_get_environment_variables();
+        let client = failing_create_database_client(env.databse_url.clone());
+
+        let db_init_result = mock_set_init_database_table(client);
+        assert!(db_init_result.is_err());
+    }
+
+    #[test]
+    fn test_listener_binding() {
+        let env = mock_get_environment_variables();
+        let listener = TcpListener::bind(env.server_adress_and_port.clone());
+        assert!(listener.is_ok(), "Listener should bind to address");
+    }
+}