fix: Normalize server address to handle missing trailing slash (serverpod#4406)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: SandPod <137198655+SandPod@users.noreply.github.com>

Author: Copilot

packages/serverpod_client/lib/src/serverpod_client_shared.dart

@@ -218,7 +218,7 @@ abstract class ServerpodClientShared extends EndpointCaller {
 
   /// Creates a new ServerpodClientShared.
   ServerpodClientShared(
-    this.host,
+    String host,
     this.serializationManager, {
     dynamic securityContext,
     @Deprecated(
@@ -230,15 +230,12 @@ abstract class ServerpodClientShared extends EndpointCaller {
     this.onFailedCall,
     this.onSucceededCall,
     bool? disconnectStreamsOnLostInternetConnection,
-  }) : connectionTimeout = connectionTimeout ?? const Duration(seconds: 20),
+  }) : host = host.endsWith('/') ? host : '$host/',
+       connectionTimeout = connectionTimeout ?? const Duration(seconds: 20),
        streamingConnectionTimeout =
            streamingConnectionTimeout ?? const Duration(seconds: 5) {
     assert(
-      host.endsWith('/'),
-      'host must end with a slash, eg: https://example.com/',
-    );
-    assert(
-      host.startsWith('http://') || host.startsWith('https://'),
+      this.host.startsWith('http://') || this.host.startsWith('https://'),
       'host must include protocol, eg: https://example.com/',
     );
     _requestDelegate = ServerpodClientRequestDelegateImpl(

packages/serverpod_client/test/host_normalization_test.dart

@@ -0,0 +1,55 @@
+import 'package:test/test.dart';
+
+import 'test_utils/test_serverpod_client.dart';
+
+void main() {
+  test(
+    'Given a server address without trailing slash when initializing client then host should have trailing slash added.',
+    () {
+      var client = TestServerpodClient(
+        host: Uri.parse('http://localhost:8080'),
+      );
+      expect(client.host, 'http://localhost:8080/');
+    },
+  );
+
+  test(
+    'Given a server address with trailing slash when initializing client then host should remain unchanged.',
+    () {
+      var client = TestServerpodClient(
+        host: Uri.parse('http://localhost:8080/'),
+      );
+      expect(client.host, 'http://localhost:8080/');
+    },
+  );
+
+  test(
+    'Given an HTTPS server address without trailing slash when initializing client then host should have trailing slash added.',
+    () {
+      var client = TestServerpodClient(
+        host: Uri.parse('https://example.com'),
+      );
+      expect(client.host, 'https://example.com/');
+    },
+  );
+
+  test(
+    'Given a server address with path and without trailing slash when initializing client then host should have trailing slash added.',
+    () {
+      var client = TestServerpodClient(
+        host: Uri.parse('http://localhost:8080/api'),
+      );
+      expect(client.host, 'http://localhost:8080/api/');
+    },
+  );
+
+  test(
+    'Given a server address with path and with trailing slash when initializing client then host should remain unchanged.',
+    () {
+      var client = TestServerpodClient(
+        host: Uri.parse('http://localhost:8080/api/'),
+      );
+      expect(client.host, 'http://localhost:8080/api/');
+    },
+  );
+}

packages/serverpod_client/test/test_utils/test_serverpod_client.dart

@@ -9,7 +9,7 @@ class TestServerpodClient extends ServerpodClientShared {
     required Uri host,
     ClientAuthKeyProvider? authKeyProvider,
   }) : super(
-         '${host.toString()}/',
+         host.toString(),
          TestSerializationManager(),
          streamingConnectionTimeout: const Duration(seconds: 5),
          connectionTimeout: const Duration(seconds: 20),