Update missing filter handling to treat is as disabled when requirement all (#590)

Author: linglingye001

src/Microsoft.FeatureManagement/FeatureManager.cs

@@ -418,15 +418,6 @@ private async ValueTask<bool> IsEnabledAsync<TContext>(FeatureDefinition feature
             }
             else
             {
-                //
-                // Ensure no conflicts in the feature definition
-                if (featureDefinition.RequirementType == RequirementType.All && _options.IgnoreMissingFeatureFilters)
-                {
-                    throw new FeatureManagementException(
-                        FeatureManagementError.Conflict,
-                        $"The 'IgnoreMissingFeatureFilters' flag cannot be used in combination with a feature of requirement type 'All'.");
-                }
-
                 //
                 // If the requirement type is all, we default to true. Requirement type All will end on a false
                 enabled = featureDefinition.RequirementType == RequirementType.All;
@@ -491,6 +482,15 @@ private async ValueTask<bool> IsEnabledAsync<TContext>(FeatureDefinition feature
 
                         Logger?.LogWarning(FeatureFilterNotFoundError, featureFilterConfiguration.Name, featureDefinition.Name);
 
+                        //
+                        // If requirement type is All, a missing filter means the feature cannot be enabled
+                        if (featureDefinition.RequirementType == RequirementType.All)
+                        {
+                            enabled = false;
+
+                            break;
+                        }
+
                         continue;
                     }
 

tests/Tests.FeatureManagement/FeatureManagementTest.cs

@@ -796,7 +796,7 @@ public async Task UsesRequirementType()
         }
 
         [Fact]
-        public async Task RequirementTypeAllExceptions()
+        public async Task RequirementTypeAllWithIgnoreMissingFeatureFilters()
         {
             IConfiguration config = new ConfigurationBuilder().AddJsonFile("appsettings.json").Build();
 
@@ -816,12 +816,12 @@ public async Task RequirementTypeAllExceptions()
 
             IFeatureManager featureManager = serviceProvider.GetRequiredService<IFeatureManager>();
 
+            //
+            // AllFilterFeature has RequirementType.All with missing filters.
+            // With IgnoreMissingFeatureFilters enabled, the feature should be treated as disabled.
             string allFilterFeature = Features.AllFilterFeature;
 
-            await Assert.ThrowsAsync<FeatureManagementException>(async () =>
-            {
-                await featureManager.IsEnabledAsync(allFilterFeature);
-            });
+            Assert.False(await featureManager.IsEnabledAsync(allFilterFeature));
         }
 
         [Fact]