if filter name can be found, exception will not be thrown (#314)

Author: zhiyuanliang-ms

src/Microsoft.FeatureManagement/FeatureManager.cs

@@ -202,6 +202,14 @@ private async Task<bool> IsEnabledAsync<TContext>(string feature, TContext appCo
 
                         if (filter == null)
                         {
+                            if (_featureFilters.Any(f => IsMatchingName(f.GetType(), featureFilterConfiguration.Name)))
+                            {
+                                //
+                                // Cannot find the appropriate registered feature filter which matches the filter name and the provided context type.
+                                // But there is a registered feature filter which matches the filter name.
+                                continue;
+                            }
+
                             string errorMessage = $"The feature filter '{featureFilterConfiguration.Name}' specified for feature '{feature}' was not found.";
 
                             if (!_options.IgnoreMissingFeatureFilters)

tests/Tests.FeatureManagement/FeatureManagement.cs

@@ -237,25 +237,33 @@ public async Task AllowsDuplicatedFilterAlias()
                 });
 
             Assert.Equal($"Multiple contextual feature filters match the configured filter named '{duplicatedFilterName}' and context type '{typeof(DummyContext)}'.", ex.Message);
+        }
 
-            services = new ServiceCollection();
+        [Fact]
+        public async Task SkipsContextualFilterEvaluationForUnrecognizedContext()
+        {
+            string featureName = Features.FeatureUsesFiltersWithDuplicatedAlias;
+
+            IConfiguration config = new ConfigurationBuilder().AddJsonFile("appsettings.json").Build();
+
+            var services = new ServiceCollection();
 
             services
                 .AddSingleton(config)
                 .AddFeatureManagement()
                 .AddFeatureFilter<ContextualDuplicatedAliasFeatureFilterWithAccountContext>();
 
-            serviceProvider = services.BuildServiceProvider();
+            ServiceProvider serviceProvider = services.BuildServiceProvider();
 
-            featureManager = serviceProvider.GetRequiredService<IFeatureManager>();
+            IFeatureManager featureManager = serviceProvider.GetRequiredService<IFeatureManager>();
 
-            ex = await Assert.ThrowsAsync<FeatureManagementException>(
-                async () =>
-                {
-                    await featureManager.IsEnabledAsync(featureName);
-                });
+            var appContext = new AppContext();
+
+            var dummyContext = new DummyContext();
 
-            Assert.Equal($"The feature filter '{duplicatedFilterName}' specified for feature '{featureName}' was not found.", ex.Message);
+            Assert.True(await featureManager.IsEnabledAsync(featureName));
+
+            Assert.True(await featureManager.IsEnabledAsync(featureName, dummyContext));
         }
 
         [Fact]