Fix bug with feature flag and key-value select ordering (#629)

* fix select order bug with feature flags

* update to use default query static selector

Author: amerjusupovic

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationOptions.cs

@@ -22,6 +22,7 @@ public class AzureAppConfigurationOptions
     {
         private const int MaxRetries = 2;
         private static readonly TimeSpan MaxRetryDelay = TimeSpan.FromMinutes(1);
+        private static readonly KeyValueSelector DefaultQuery = new KeyValueSelector { KeyFilter = KeyFilter.Any, LabelFilter = LabelFilter.Null };
 
         private List<KeyValueWatcher> _individualKvWatchers = new List<KeyValueWatcher>();
         private List<KeyValueWatcher> _ffWatchers = new List<KeyValueWatcher>();
@@ -159,7 +160,7 @@ public AzureAppConfigurationOptions()
             };
 
             // Adds the default query to App Configuration if <see cref="Select"/> and <see cref="SelectSnapshot"/> are never called.
-            _selectors = new List<KeyValueSelector> { new KeyValueSelector { KeyFilter = KeyFilter.Any, LabelFilter = LabelFilter.Null } };
+            _selectors = new List<KeyValueSelector> { DefaultQuery };
         }
 
         /// <summary>
@@ -201,7 +202,7 @@ public AzureAppConfigurationOptions Select(string keyFilter, string labelFilter
 
             if (!_selectCalled)
             {
-                _selectors.Clear();
+                _selectors.Remove(DefaultQuery);
 
                 _selectCalled = true;
             }
@@ -229,7 +230,7 @@ public AzureAppConfigurationOptions SelectSnapshot(string name)
 
             if (!_selectCalled)
             {
-                _selectors.Clear();
+                _selectors.Remove(DefaultQuery);
 
                 _selectCalled = true;
             }

tests/Tests.AzureAppConfiguration/FeatureManagementTests.cs

@@ -1066,6 +1066,63 @@ public void SelectFeatureFlags()
             Assert.Null(config["FeatureManagement:App2_Feature2"]);
         }
 
+        [Fact]
+        public void SelectOrderDoesNotAffectLoad()
+        {
+            var mockResponse = new Mock<Response>();
+            var mockClient = new Mock<ConfigurationClient>(MockBehavior.Strict);
+
+            List<ConfigurationSetting> kvCollection = new List<ConfigurationSetting>
+            {
+                ConfigurationModelFactory.ConfigurationSetting("TestKey1", "TestValue1", "label",
+                    eTag: new ETag("0a76e3d7-7ec1-4e37-883c-9ea6d0d89e63")),
+                ConfigurationModelFactory.ConfigurationSetting("TestKey2", "TestValue2", "label",
+                    eTag: new ETag("31c38369-831f-4bf1-b9ad-79db56c8b989"))
+            };
+
+            MockAsyncPageable GetTestKeys(SettingSelector selector, CancellationToken ct)
+            {
+                List<ConfigurationSetting> settingCollection;
+
+                if (selector.KeyFilter.StartsWith(FeatureManagementConstants.FeatureFlagMarker))
+                {
+                    settingCollection = _featureFlagCollection;
+                }
+                else
+                {
+                    settingCollection = kvCollection;
+                }
+
+                var copy = new List<ConfigurationSetting>();
+                var newSetting = settingCollection.FirstOrDefault(s => (s.Key == selector.KeyFilter && s.Label == selector.LabelFilter));
+                if (newSetting != null)
+                    copy.Add(TestHelpers.CloneSetting(newSetting));
+                return new MockAsyncPageable(copy);
+            }
+
+            mockClient.Setup(c => c.GetConfigurationSettingsAsync(It.IsAny<SettingSelector>(), It.IsAny<CancellationToken>()))
+                .Returns((Func<SettingSelector, CancellationToken, MockAsyncPageable>)GetTestKeys);
+
+            var config = new ConfigurationBuilder()
+                .AddAzureAppConfiguration(options =>
+                {
+                    options.ClientManager = TestHelpers.CreateMockedConfigurationClientManager(mockClient.Object);
+                    options.UseFeatureFlags(ff =>
+                    {
+                        ff.Select("App1_Feature1", "App1_Label");
+                        ff.Select("App2_Feature1", "App2_Label");
+                    });
+                    options.Select("TestKey1", "label");
+                    options.Select("TestKey2", "label");
+                })
+                .Build();
+
+            Assert.Equal("True", config["FeatureManagement:App1_Feature1"]);
+            Assert.Equal("False", config["FeatureManagement:App2_Feature1"]);
+            Assert.Equal("TestValue1", config["TestKey1"]);
+            Assert.Equal("TestValue2", config["TestKey2"]);
+        }
+
         [Fact]
         public void TestNullAndMissingValuesForConditions()
         {