Add baseline unit tests and fix home server normalization

test/auth_helpers_test.dart

@@ -0,0 +1,89 @@
+import 'package:chat_server/src/handlers/auth_handlers.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('parseUserId', () {
+    test('parses valid userId', () {
+      final parsed = parseUserId('alice@example.com');
+      expect(parsed, isNotNull);
+      expect(parsed!.username, 'alice');
+      expect(parsed.host, 'example.com');
+    });
+
+    test('returns null for invalid userId', () {
+      expect(parseUserId('alice'), isNull);
+      expect(parseUserId('alice@'), isNull);
+      expect(parseUserId('@example.com'), isNull);
+      expect(parseUserId('alice@example.com@x'), isNull);
+    });
+  });
+
+  group('defaultSchemeForHost', () {
+    test('returns http for localhost-style hosts', () {
+      expect(defaultSchemeForHost('localhost:9870'), 'http');
+      expect(defaultSchemeForHost('127.0.0.1:9870'), 'http');
+      expect(defaultSchemeForHost('[::1]:9870'), 'http');
+    });
+
+    test('returns https for non-local hosts', () {
+      expect(defaultSchemeForHost('chat.example.com'), 'https');
+    });
+  });
+
+  group('normalizeHomeServer', () {
+    test('normalizes host without scheme', () {
+      expect(
+        normalizeHomeServer('chat.example.com'),
+        'https://chat.example.com',
+      );
+      expect(
+        normalizeHomeServer('localhost:9870'),
+        'http://localhost:9870',
+      );
+    });
+
+    test('strips trailing slash/path/query/fragment', () {
+      expect(
+        normalizeHomeServer('https://example.com/a/b?x=1#y'),
+        'https://example.com',
+      );
+      expect(
+        normalizeHomeServer('https://example.com/'),
+        'https://example.com',
+      );
+    });
+
+    test('returns null for invalid input', () {
+      expect(normalizeHomeServer(''), isNull);
+      expect(normalizeHomeServer('://bad'), isNull);
+    });
+  });
+
+  group('homeServerMatchesUserIdHost', () {
+    test('matches host and explicit port', () {
+      expect(
+        homeServerMatchesUserIdHost(
+            'https://chat.example.com:8443', 'chat.example.com:8443'),
+        isTrue,
+      );
+      expect(
+        homeServerMatchesUserIdHost(
+            'https://chat.example.com:8443', 'chat.example.com'),
+        isFalse,
+      );
+    });
+
+    test('matches default ports when omitted', () {
+      expect(
+        homeServerMatchesUserIdHost(
+            'https://chat.example.com', 'chat.example.com:443'),
+        isTrue,
+      );
+      expect(
+        homeServerMatchesUserIdHost(
+            'http://chat.example.com', 'chat.example.com:80'),
+        isTrue,
+      );
+    });
+  });
+}