From f1031c994d93c23a2aada511ae4839f90a57e973 Mon Sep 17 00:00:00 2001
From: Michael Grosse Huelsewiesche <mihuelsewiesche@twilio.com>
Date: Mon, 2 Mar 2026 16:03:38 -0500
Subject: [PATCH] fix: handle UnimplementedError for linkStream on web platform

The web platform implementation doesn't override linkStream, causing
a crash when trackDeeplinks is enabled. This adds two layers of defense:

1. analytics_web.dart: returns an empty stream (correct platform behavior)
2. analytics.dart: catches UnimplementedError for any platform that
   doesn't implement linkStream

Also fixes a pre-existing flaky test (createClient) that used a real
StoreImpl instead of a mock, causing async PlatformNotSupportedError
from path_provider to leak across test boundaries.

Fixes #191

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 packages/core/lib/analytics.dart       | 14 +++++++----
 packages/core/lib/analytics_web.dart   |  4 +++-
 packages/core/test/analytics_test.dart | 33 +++++++++++++++++++++-----
 3 files changed, 39 insertions(+), 12 deletions(-)

diff --git a/packages/core/lib/analytics.dart b/packages/core/lib/analytics.dart
index 1508d12..932f277 100644
--- a/packages/core/lib/analytics.dart
+++ b/packages/core/lib/analytics.dart
@@ -86,11 +86,15 @@ class Analytics with ClientMethods {
   /// @param isReady
   void _onStateReady() {
     if (state.configuration.state.trackDeeplinks) {
-      AnalyticsPlatform.instance.linkStream.listen((event) {
-        if (state.configuration.state.trackDeeplinks) {
-          _trackDeepLinkEvent(DeepLinkData.fromJson(event));
-        }
-      });
+      try {
+        AnalyticsPlatform.instance.linkStream.listen((event) {
+          if (state.configuration.state.trackDeeplinks) {
+            _trackDeepLinkEvent(DeepLinkData.fromJson(event));
+          }
+        });
+      } on UnimplementedError {
+        // Deep link tracking not available on this platform (e.g. web)
+      }
     }
 
     for (var plugin in _pluginsToAdd) {
diff --git a/packages/core/lib/analytics_web.dart b/packages/core/lib/analytics_web.dart
index d1d9ada..1a21672 100644
--- a/packages/core/lib/analytics_web.dart
+++ b/packages/core/lib/analytics_web.dart
@@ -12,7 +12,9 @@ class AnalyticsPlatformImpl extends AnalyticsPlatform {
   /// Constructs a AnalyticsWeb
   AnalyticsPlatformImpl();
 
-  /// Returns a [String] containing the version of the platform.
+  @override
+  Stream<Map<String, dynamic>> get linkStream => const Stream.empty();
+
   @override
   Future<NativeContext> getContext({bool collectDeviceId = false}) async =>
       NativeContext(
diff --git a/packages/core/test/analytics_test.dart b/packages/core/test/analytics_test.dart
index 8d1e42b..6062cb5 100644
--- a/packages/core/test/analytics_test.dart
+++ b/packages/core/test/analytics_test.dart
@@ -1,6 +1,5 @@
 import 'package:segment_analytics/analytics.dart';
 import 'package:segment_analytics/analytics_platform_interface.dart';
-import 'package:segment_analytics/client.dart';
 import 'package:segment_analytics/event.dart';
 import 'package:segment_analytics/flush_policies/count_flush_policy.dart';
 import 'package:segment_analytics/flush_policies/flush_policy.dart';
@@ -128,15 +127,37 @@ void main() {
       );
     });
 
-    test("it createClient", () async {
-      Analytics analytics = createClient(Configuration("123",
-              debug: false,
+    test("it creates Analytics with trackDeeplinks and lifecycle events enabled", () async {
+      final analytics = Analytics(
+          Configuration("123",
               trackApplicationLifecycleEvents: true,
               trackDeeplinks: true,
-              token: "abcdef12345")
-              );
+              token: "abcdef12345"),
+          Mocks.store(),
+          httpClient: (_) => httpClient);
+      await analytics.init();
       expect(analytics, isA<Analytics>());
     });
+
+    test("trackDeeplinks should not crash on platform without linkStream", () async {
+      // Reproduces https://github.com/segmentio/analytics_flutter/issues/191
+      // MockPlatform does not override linkStream, simulating web platform behavior
+      AnalyticsPlatform.instance = MockPlatform();
+
+      final analytics = Analytics(
+          Configuration("123",
+              trackApplicationLifecycleEvents: false,
+              trackDeeplinks: true),
+          Mocks.store(),
+          httpClient: (_) => httpClient);
+      await analytics.init();
+
+      // Allow _onStateReady to fire via state.ready.then()
+      await Future.delayed(Duration(milliseconds: 100));
+
+      // If we get here without UnimplementedError, the test passes
+      analytics.track("test event after deeplink init");
+    });
   });
 }