Use ITargetingContext when calling GetVariantAsync (#484)

* add variant feature manager extensions

* use TContext to avoid future breaking change

* TargetingContext in EvaluationEvent

* update comments & not use ambient context in contextual case

* update comment

* use ITargetingContext & check runtime context type

* use TargetingCotnext for private method

* use var instead of type

* revert change on ContextualTestFilter

* update comment

* update comment

src/Microsoft.FeatureManagement/FeatureManager.cs

@@ -144,7 +144,7 @@ public async Task<bool> IsEnabledAsync(string feature)
         /// Checks whether a given feature is enabled.
         /// </summary>
         /// <param name="feature">The name of the feature to check.</param>
-        /// <param name="appContext">A context providing information that can be used to evaluate whether a feature should be on or off.</param>
+        /// <param name="appContext">A context that provides information to evaluate whether a feature should be on or off.</param>
         /// <returns>True if the feature is enabled, otherwise false.</returns>
         public async Task<bool> IsEnabledAsync<TContext>(string feature, TContext appContext)
         {
@@ -170,7 +170,7 @@ public async ValueTask<bool> IsEnabledAsync(string feature, CancellationToken ca
         /// Checks whether a given feature is enabled.
         /// </summary>
         /// <param name="feature">The name of the feature to check.</param>
-        /// <param name="appContext">A context providing information that can be used to evaluate whether a feature should be on or off.</param>
+        /// <param name="appContext">A context that provides information to evaluate whether a feature should be on or off.</param>
         /// <param name="cancellationToken">The cancellation token to cancel the operation.</param>
         /// <returns>True if the feature is enabled, otherwise false.</returns>
         public async ValueTask<bool> IsEnabledAsync<TContext>(string feature, TContext appContext, CancellationToken cancellationToken = default)
@@ -216,7 +216,7 @@ public async ValueTask<Variant> GetVariantAsync(string feature, CancellationToke
                 throw new ArgumentNullException(nameof(feature));
             }
 
-            EvaluationEvent evaluationEvent = await EvaluateFeature<TargetingContext>(feature, context: null, useContext: false, cancellationToken);
+            EvaluationEvent evaluationEvent = await EvaluateFeature<object>(feature, context: null, useContext: false, cancellationToken);
 
             return evaluationEvent.Variant;
         }
@@ -225,10 +225,10 @@ public async ValueTask<Variant> GetVariantAsync(string feature, CancellationToke
         /// Gets the assigned variant for a specific feature.
         /// </summary>
         /// <param name="feature">The name of the feature to evaluate.</param>
-        /// <param name="context">An instance of <see cref="TargetingContext"/> used to evaluate which variant the user will be assigned.</param>
+        /// <param name="context">A context that provides information to evaluate which variant will be assigned to the user.</param>
         /// <param name="cancellationToken">The cancellation token to cancel the operation.</param>
         /// <returns>A variant assigned to the user based on the feature's configured allocation.</returns>
-        public async ValueTask<Variant> GetVariantAsync(string feature, TargetingContext context, CancellationToken cancellationToken = default)
+        public async ValueTask<Variant> GetVariantAsync(string feature, ITargetingContext context, CancellationToken cancellationToken = default)
         {
             if (string.IsNullOrEmpty(feature))
             {
@@ -262,15 +262,19 @@ private async ValueTask<EvaluationEvent> EvaluateFeature<TContext>(string featur
 
             //
             // Determine Targeting Context
-            TargetingContext targetingContext;
+            TargetingContext targetingContext = null;
 
-            if (useContext)
+            if (!useContext)
             {
-                targetingContext = context as TargetingContext;
+                targetingContext = await ResolveTargetingContextAsync(cancellationToken).ConfigureAwait(false);
             }
-            else
+            else if (context is ITargetingContext targetingInfo)
             {
-                targetingContext = await ResolveTargetingContextAsync(cancellationToken).ConfigureAwait(false);
+                targetingContext = new TargetingContext
+                {
+                    UserId = targetingInfo.UserId,
+                    Groups = targetingInfo.Groups
+                };
             }
 
             evaluationEvent.TargetingContext = targetingContext;
@@ -314,7 +318,7 @@ private async ValueTask<EvaluationEvent> EvaluateFeature<TContext>(string featur
 
                             if (useContext)
                             {
-                                message = $"A {nameof(TargetingContext)} required for variant assignment was not provided.";
+                                message = $"The context of type {context.GetType().Name} does not implement {nameof(ITargetingContext)} for variant assignment.";
                             }
                             else if (TargetingContextAccessor == null)
                             {
@@ -496,7 +500,7 @@ private async ValueTask<bool> IsEnabledAsync<TContext>(FeatureDefinition feature
 
                     if (useAppContext)
                     {
-                        filter = GetFeatureFilterMetadata(featureFilterConfiguration.Name, typeof(TContext)) ??
+                        filter = GetFeatureFilterMetadata(featureFilterConfiguration.Name, appContext.GetType()) ??
                                  GetFeatureFilterMetadata(featureFilterConfiguration.Name);
                     }
                     else
@@ -538,7 +542,7 @@ private async ValueTask<bool> IsEnabledAsync<TContext>(FeatureDefinition feature
                     // IContextualFeatureFilter
                     if (useAppContext)
                     {
-                        ContextualFeatureFilterEvaluator contextualFilter = GetContextualFeatureFilter(featureFilterConfiguration.Name, typeof(TContext));
+                        ContextualFeatureFilterEvaluator contextualFilter = GetContextualFeatureFilter(featureFilterConfiguration.Name, appContext.GetType());
 
                         if (contextualFilter != null &&
                             await contextualFilter.EvaluateAsync(context, appContext).ConfigureAwait(false) == targetEvaluation)

src/Microsoft.FeatureManagement/FeatureManagerSnapshot.cs

@@ -97,7 +97,7 @@ public async ValueTask<Variant> GetVariantAsync(string feature, CancellationToke
             return variant;
         }
 
-        public async ValueTask<Variant> GetVariantAsync(string feature, TargetingContext context, CancellationToken cancellationToken)
+        public async ValueTask<Variant> GetVariantAsync(string feature, ITargetingContext context, CancellationToken cancellationToken)
         {
             string cacheKey = GetVariantCacheKey(feature);
 

src/Microsoft.FeatureManagement/IFeatureManager.cs

@@ -28,7 +28,7 @@ public interface IFeatureManager
         /// Checks whether a given feature is enabled.
         /// </summary>
         /// <param name="feature">The name of the feature to check.</param>
-        /// <param name="context">A context providing information that can be used to evaluate whether a feature should be on or off.</param>
+        /// <param name="context">A context that provides information to evaluate whether a feature should be on or off.</param>
         /// <returns>True if the feature is enabled, otherwise false.</returns>
         Task<bool> IsEnabledAsync<TContext>(string feature, TContext context);
     }

src/Microsoft.FeatureManagement/IVariantFeatureManager.cs

@@ -32,7 +32,7 @@ public interface IVariantFeatureManager
         /// Checks whether a given feature is enabled.
         /// </summary>
         /// <param name="feature">The name of the feature to check.</param>
-        /// <param name="context">A context providing information that can be used to evaluate whether a feature should be on or off.</param>
+        /// <param name="context">A context that provides information to evaluate whether a feature should be on or off.</param>
         /// <param name="cancellationToken">The cancellation token to cancel the operation.</param>
         /// <returns>True if the feature is enabled, otherwise false.</returns>
         ValueTask<bool> IsEnabledAsync<TContext>(string feature, TContext context, CancellationToken cancellationToken = default);
@@ -49,9 +49,9 @@ public interface IVariantFeatureManager
         /// Gets the assigned variant for a specific feature.
         /// </summary>
         /// <param name="feature">The name of the feature to evaluate.</param>
-        /// <param name="context">An instance of <see cref="TargetingContext"/> used to evaluate which variant the user will be assigned.</param>
+        /// <param name="context">A context that provides information to evaluate which variant will be assigned to the user.</param>
         /// <param name="cancellationToken">The cancellation token to cancel the operation.</param>
         /// <returns>A variant assigned to the user based on the feature's configured allocation.</returns>
-        ValueTask<Variant> GetVariantAsync(string feature, TargetingContext context, CancellationToken cancellationToken = default);
+        ValueTask<Variant> GetVariantAsync(string feature, ITargetingContext context, CancellationToken cancellationToken = default);
     }
 }

src/Microsoft.FeatureManagement/VariantFeatureManagerExtensions.cs

@@ -0,0 +1,28 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+//
+using Microsoft.FeatureManagement.FeatureFilters;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.FeatureManagement
+{
+    /// <summary>
+    /// Extensions for <see cref="IVariantFeatureManager"/>.
+    /// </summary>
+    public static class VariantFeatureManagerExtensions
+    {
+        /// <summary>
+        /// Gets the assigned variant for a specific feature.
+        /// </summary>
+        /// <param name="variantFeatureManager">The <see cref="IVariantFeatureManager"/> instance.</param>
+        /// <param name="feature">The name of the feature to evaluate.</param>
+        /// <param name="context">An instance of <see cref="TargetingContext"/> used to evaluate which variant the user will be assigned.</param>
+        /// <param name="cancellationToken">The cancellation token to cancel the operation.</param>
+        /// <returns>A variant assigned to the user based on the feature's configured allocation.</returns>
+        public static ValueTask<Variant> GetVariantAsync(this IVariantFeatureManager variantFeatureManager, string feature, TargetingContext context, CancellationToken cancellationToken = default)
+        {
+            return variantFeatureManager.GetVariantAsync(feature, context, cancellationToken);
+        }
+    }
+}

tests/Tests.FeatureManagement/AppContext.cs

@@ -1,10 +1,17 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 //
+using Microsoft.FeatureManagement.FeatureFilters;
+using System.Collections.Generic;
+
 namespace Tests.FeatureManagement
 {
-    class AppContext : IAccountContext
+    class AppContext : IAccountContext, ITargetingContext
     {
         public string AccountId { get; set; }
+
+        public string UserId { get; set; }
+
+        public IEnumerable<string> Groups { get; set; }
     }
 }

tests/Tests.FeatureManagement/FeatureManagementTest.cs

@@ -503,7 +503,7 @@ public async Task UsesContext()
 
             IFeatureManager featureManager = provider.GetRequiredService<IFeatureManager>();
 
-            AppContext context = new AppContext();
+            var context = new AppContext();
 
             context.AccountId = "NotEnabledAccount";
 
@@ -1641,6 +1641,53 @@ public async Task VariantBasedInjection()
                 }
             );
         }
+
+        [Fact]
+        public async Task VariantFeatureFlagWithContextualFeatureFilter()
+        {
+            IConfiguration configuration = new ConfigurationBuilder()
+                .AddJsonFile("appsettings.json")
+                .Build();
+
+            IServiceCollection services = new ServiceCollection();
+
+            services.AddSingleton(configuration)
+                .AddFeatureManagement()
+                .AddFeatureFilter<ContextualTestFilter>();
+
+            ServiceProvider serviceProvider = services.BuildServiceProvider();
+
+            ContextualTestFilter contextualTestFeatureFilter = (ContextualTestFilter)serviceProvider.GetRequiredService<IEnumerable<IFeatureFilterMetadata>>().First(f => f is ContextualTestFilter);
+
+            contextualTestFeatureFilter.ContextualCallback = (ctx, accountContext) =>
+            {
+                var allowedAccounts = new List<string>();
+
+                ctx.Parameters.Bind("AllowedAccounts", allowedAccounts);
+
+                return allowedAccounts.Contains(accountContext.AccountId);
+            };
+
+            IVariantFeatureManager featureManager = serviceProvider.GetRequiredService<IVariantFeatureManager>();
+
+            var context = new AppContext();
+
+            context.AccountId = "NotEnabledAccount";
+
+            Assert.False(await featureManager.IsEnabledAsync(Features.ContextualFeatureWithVariant, context));
+
+            Variant variant = await featureManager.GetVariantAsync(Features.ContextualFeatureWithVariant, context);
+
+            Assert.Equal("Small", variant.Name);
+
+            context.AccountId = "abc";
+
+            Assert.True(await featureManager.IsEnabledAsync(Features.ContextualFeatureWithVariant, context));
+
+            variant = await featureManager.GetVariantAsync(Features.ContextualFeatureWithVariant, context);
+
+            Assert.Equal("Big", variant.Name);
+        }
     }
 
     public class FeatureManagementTelemetryTest

tests/Tests.FeatureManagement/Features.cs

@@ -30,5 +30,6 @@ static class Features
         public const string VariantImplementationFeature = "VariantImplementationFeature";
         public const string OnTelemetryTestFeature = "OnTelemetryTestFeature";
         public const string OffTelemetryTestFeature = "OffTelemetryTestFeature";
+        public const string ContextualFeatureWithVariant = "ContextualFeatureWithVariant";
     }
 }

tests/Tests.FeatureManagement/appsettings.json

@@ -530,6 +530,34 @@
         "telemetry": {
           "enabled": true
         }
+      },
+      {
+        "id": "ContextualFeatureWithVariant",
+        "enabled": true,
+        "conditions": {
+          "client_filters": [
+            {
+              "name": "ContextualTest",
+              "parameters": {
+                "AllowedAccounts": [
+                  "abc"
+                ]
+              }
+            }
+          ]
+        },
+        "variants": [
+          {
+            "name": "Big"
+          },
+          {
+            "name": "Small"
+          }
+        ],
+        "allocation": {
+          "default_when_enabled": "Big",
+          "default_when_disabled": "Small"
+        }
       }
     ]
   }