add environment variable class

Author: zhiyuanliang-ms

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

@@ -0,0 +1,19 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+//
+namespace Microsoft.Extensions.Configuration.AzureAppConfiguration
+{
+    /// <summary>
+    /// Environment variables used to configure Azure App Configuration provider behavior.
+    /// </summary>
+    public static class AzureAppConfigurationEnvironmentVariables
+    {
+        /// <summary>
+        /// Environment variable to disable Feature Management schema compatibility.
+        /// The value of this variable is a boolean string, e.g. "true" or "false".
+        /// When set to "true", schema compatibility checks for feature flags are disabled,
+        /// and all feature flags will be interpreted using the Microsoft Feature Flags schema.
+        /// </summary>
+        public const string DisableFmSchemaCompatibility = "AZURE_APP_CONFIGURATION_FM_SCHEMA_COMPATIBILITY_DISABLED";
+    }
+}

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/FeatureManagement/FeatureManagementKeyValueAdapter.cs

@@ -19,7 +19,6 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration.FeatureManage
 {
     internal class FeatureManagementKeyValueAdapter : IKeyValueAdapter
     {
-        private const string DisableFmSchemaCompatibilityEnvironmentVariable = "AZURE_APP_CONFIGURATION_FM_SCHEMA_COMPATIBILITY_DISABLED";
         private FeatureFlagTracing _featureFlagTracing;
         private int _featureFlagIndex = 0;
         private bool _fmSchemaCompatibilityDisabled = false;
@@ -32,7 +31,7 @@ public FeatureManagementKeyValueAdapter(FeatureFlagTracing featureFlagTracing)
 
             try
             {
-                fmSchemaCompatibilityDisabled = Environment.GetEnvironmentVariable(DisableFmSchemaCompatibilityEnvironmentVariable);
+                fmSchemaCompatibilityDisabled = Environment.GetEnvironmentVariable(AzureAppConfigurationEnvironmentVariables.DisableFmSchemaCompatibility);
             }
             catch (SecurityException) { }
 

tests/Tests.AzureAppConfiguration/Unit/FeatureManagementTests.cs

@@ -2309,7 +2309,7 @@ public void EnvironmentVariableForcesMicrosoftSchemaForAllFlags()
             try
             {
                 // Act - Set environment variable to force Microsoft schema
-                Environment.SetEnvironmentVariable("AZURE_APP_CONFIGURATION_FM_SCHEMA_COMPATIBILITY_DISABLED", "true");
+                Environment.SetEnvironmentVariable(AzureAppConfigurationEnvironmentVariables.DisableFmSchemaCompatibility, "true");
 
                 var config = new ConfigurationBuilder()
                     .AddAzureAppConfiguration(options =>