add new options for json state string parser

Author: lucasteles

src/Backdash/Options/SyncTestOptions.cs

@@ -85,9 +85,8 @@ public SyncTestOptions<TInput> UseJsonStateParser(JsonSerializerOptions? options
     /// <inheritdoc cref="UseJsonStateParser(JsonSerializerOptions?)" />
     public SyncTestOptions<TInput> UseJsonStateParser(Action<JsonSerializerOptions> configure)
     {
-        var options = JsonStateStringParser.CreateDefaultJsonOptions();
-        configure.Invoke(options);
-        return UseJsonStateParser(options);
+        StateStringParser = new JsonStateStringParser(configure);
+        return this;
     }
 
     /// <inheritdoc cref="StateStringParser" />

src/Backdash/Synchronizing/State/IStateStringParser.cs

@@ -53,22 +53,35 @@ public sealed class JsonStateStringParser(
     /// <summary>Singleton instance</summary>
     public static IStateStringParser Singleton => singleton.Value;
 
-    internal Logger? Logger = null;
-    readonly JsonSerializerOptions jsonOptions = options ?? CreateDefaultJsonOptions();
-    readonly IStateStringParser fallback = stateStringFallback ?? new DefaultStateStringParser();
-    readonly HexStateStringParser nullFallback = new();
-
-    internal static JsonSerializerOptions CreateDefaultJsonOptions() =>
-        new()
+    static JsonSerializerOptions CreateDefaultJsonOptions(Action<JsonSerializerOptions>? configure = null)
+    {
+        JsonSerializerOptions options = new()
         {
             WriteIndented = true,
             IncludeFields = true,
             AllowTrailingCommas = true,
+            DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
             ReferenceHandler = ReferenceHandler.IgnoreCycles,
             Encoder = JavaScriptEncoder.UnsafeRelaxedJsonEscaping,
             Converters = { new JsonStringEnumConverter() },
         };
 
+        configure?.Invoke(options);
+        return options;
+    }
+
+    internal Logger? Logger = null;
+    readonly JsonSerializerOptions jsonOptions = options ?? CreateDefaultJsonOptions();
+    readonly IStateStringParser fallback = stateStringFallback ?? new DefaultStateStringParser();
+    readonly HexStateStringParser nullFallback = new();
+
+    /// <summary>
+    /// Create and configure a JSON <see cref="IStateStringParser"/>
+    /// </summary>
+    public JsonStateStringParser(Action<JsonSerializerOptions> configure,
+        IStateStringParser? stateStringFallback = null) :
+        this(CreateDefaultJsonOptions(configure), stateStringFallback) { }
+
     /// <inheritdoc />
     public string GetStateString(in Frame frame, ref readonly BinaryBufferReader reader, object? currentState)
     {