refactor: improve SSE types and testing utilities

- Enhanced SSE event type definitions with more precise typing
- Added type guard and safe type assertion functions for mock objects
- Updated security test suite to use new type utilities
- Improved type safety for token validation and mock function handling
- Refined event data type to support more flexible event structures

src/sse/types.ts

@@ -12,9 +12,13 @@ export interface SSEClient {
     connectionTime: number;
 }
 
+export interface HassEventData {
+    [key: string]: unknown;
+}
+
 export interface SSEEvent {
     event_type: string;
-    data: unknown;
+    data: HassEventData;
     origin: string;
     time_fired: string;
     context: {
@@ -39,4 +43,20 @@ export interface SSEManagerConfig {
 }
 
 export type MockSendFn = (data: string) => void;
-export type MockSend = Mock<MockSendFn>; 
+export type MockSend = Mock<MockSendFn>;
+
+export type ValidateTokenFn = (token: string, ip?: string) => { valid: boolean; error?: string };
+export type MockValidateToken = Mock<ValidateTokenFn>;
+
+// Type guard for mock functions
+export function isMockFunction(value: unknown): value is Mock<unknown> {
+    return typeof value === 'function' && 'mock' in value;
+}
+
+// Safe type assertion for mock objects
+export function asMockFunction<T extends (...args: any[]) => any>(value: unknown): Mock<T> {
+    if (!isMockFunction(value)) {
+        throw new Error('Value is not a mock function');
+    }
+    return value as Mock<T>;
+}