feat(fx): allow empty param array parameter

src/Flandre.Framework/Common/CommandParameter.cs

@@ -1,24 +1,45 @@
 namespace Flandre.Framework.Common;
 
+/// <summary>
+/// 指令参数
+/// </summary>
 public sealed class CommandParameter
 {
+    /// <summary>
+    /// 参数名称
+    /// </summary>
     public string Name { get; }
 
+    /// <summary>
+    /// 参数类型
+    /// </summary>
     public Type Type { get; }
 
+    /// <summary>
+    /// 参数默认值
+    /// </summary>
     public object? DefaultValue { get; }
 
+    /// <summary>
+    /// 参数描述
+    /// </summary>
     public string? Description { get; init; }
 
+    /// <summary>
+    /// 是否被 params 修饰
+    /// </summary>
     public bool IsParamArray { get; }
 
+    /// <summary>
+    /// 是否为必须参数
+    /// </summary>
     public bool IsRequired => DefaultValue is null;
 
     internal CommandParameter(string name, Type type, object? defaultValue, bool isParamArray)
     {
         Name = name;
         Type = type;
-        DefaultValue = defaultValue;
+        DefaultValue = isParamArray ? Array.CreateInstance(type.GetElementType()!, 0) : defaultValue;
         IsParamArray = isParamArray;
     }
 }

tests/Flandre.Framework.Tests/CommandTests.cs

@@ -145,6 +145,9 @@ public void TestArrayParameter()
 
         var content = client.SendMessageForReply("test6 1.23 aaa bbb ccc  ");
         Assert.Equal("1.23 | aaa,bbb,ccc", content?.GetText());
+
+        content = client.SendMessageForReply("test6 2.34");
+        Assert.Equal("2.34 | ", content?.GetText());
     }
 
     [Fact]