1342 allow to set permissions to exclude to empty array overriding defaults (#1347)

* adjustments

* Add function to define the list based on config key presence and provided default

* Add method to initialize permissions

* Set initial PermissionsToExclude property to empty array

* fix: Throw ArgumentNullException if null

* fix: Rename list to configuredList

* fix: Revert intial value of PermissionsToExclude to null

* fix: Add explanatory comment

* Cosmetic updates

---------

Co-authored-by: Waldek Mastykarz <waldek@mastykarz.nl>

Author: bartizan

DevProxy.Abstractions/Plugins/BasePlugin.cs

@@ -114,6 +114,30 @@ public override async Task InitializeAsync(InitArgs e, CancellationToken cancell
         }
     }
 
+    /// <summary>
+    /// <para>Evaluates the <paramref name="key"/> array property.
+    ///   If the property exists, the <paramref name="configuredList"/> value is used;
+    ///   otherwise, the default <paramref name="defaultList"/> is applied.</para>
+    /// <para>If the property is <i>null</i>, it is interpreted as an empty array (<i>[]</i>).</para>
+    /// <para>Note: This is necessary because .NET configuration binding cannot differentiate between an empty array,
+    ///   a null value, or a missing property in appsettings.json.
+    ///   See at <see cref="https://github.com/dotnet/runtime/issues/58930"/>
+    /// </para>
+    /// </summary>
+    /// <param name="key">The array property name</param>
+    /// <param name="configuredList">The configured list of string values</param>
+    /// <param name="defaultList">The default list of string values</param>
+    /// <returns>Returns the result list of string values</returns>
+    protected virtual IEnumerable<string>? GetConfigurationValue(string key, IEnumerable<string>? configuredList,
+        IEnumerable<string>? defaultList = default)
+    {
+        ArgumentNullException.ThrowIfNull(key, nameof(key));
+
+        var keyExists = ConfigurationSection.GetChildren().Any(f => string.Equals(key, f.Key, StringComparison.Ordinal));
+        configuredList = configuredList?.Where(static p => !string.IsNullOrEmpty(p));
+        return keyExists ? configuredList ?? [] : defaultList;
+    }
+
     private async Task<(bool IsValid, IEnumerable<string> ValidationErrors)> ValidatePluginConfigAsync(CancellationToken cancellationToken)
     {
         if (!ProxyConfiguration.ValidateSchemas)

DevProxy.Plugins/Extensions/StringExtensions.cs

@@ -67,11 +67,9 @@ internal static string ToCamelCase(this string str)
     {
         if (string.IsNullOrEmpty(str))
         {
-
             return str;
         }
 
-
         return char.ToLowerInvariant(str[0]) + str[1..];
     }
 

DevProxy.Plugins/Reporting/GraphMinimalPermissionsGuidancePlugin.cs

@@ -61,20 +61,7 @@ public override async Task InitializeAsync(InitArgs e, CancellationToken cancell
 
         _graphUtils = ActivatorUtilities.CreateInstance<GraphUtils>(e.ServiceProvider);
 
-        // we need to do it this way because .NET doesn't distinguish between
-        // an empty array and a null value and we want to be able to tell
-        // if the user hasn't specified a value and we should use the default
-        // set or if they have specified an empty array and we shouldn't exclude
-        // any permissions
-        if (Configuration.PermissionsToExclude is null)
-        {
-            Configuration.PermissionsToExclude = ["profile", "openid", "offline_access", "email"];
-        }
-        else
-        {
-            // remove empty strings
-            Configuration.PermissionsToExclude = Configuration.PermissionsToExclude.Where(p => !string.IsNullOrEmpty(p));
-        }
+        InitializePermissionsToExclude();
     }
 
     public override async Task AfterRecordingStopAsync(RecordingArgs e, CancellationToken cancellationToken)
@@ -220,6 +207,15 @@ public override async Task AfterRecordingStopAsync(RecordingArgs e, Cancellation
         Logger.LogTrace("Left {Name}", nameof(AfterRecordingStopAsync));
     }
 
+    private void InitializePermissionsToExclude()
+    {
+        var key = nameof(GraphMinimalPermissionsGuidancePluginConfiguration.PermissionsToExclude)
+            .ToCamelCase();
+
+        string[] defaultPermissionsToExclude = ["profile", "openid", "offline_access", "email"];
+        Configuration.PermissionsToExclude = GetConfigurationValue(key, Configuration.PermissionsToExclude, defaultPermissionsToExclude);
+    }
+
     private async Task EvaluateMinimalScopesAsync(
         IEnumerable<(string method, string url)> endpoints,
         IEnumerable<string> permissionsFromAccessToken,