fix: update ConfiginfoTests for optional InstallPath validation

Validate_InstallPathNullOrWhitespace_ThrowsArgumentException →
Validate_InstallPathNullOrWhitespace_NoException

InstallPath is no longer required in Validate(); it defaults to
AppDomain.CurrentDomain.BaseDirectory via BaseConfigInfo.

Author: JusterZhu

tests/CoreTest/Configuration/ConfiginfoTests.cs

@@ -167,7 +167,7 @@ public void Validate_ClientVersionNullOrWhitespace_ThrowsArgumentException(strin
     [InlineData(null)]
     [InlineData("")]
     [InlineData("   ")]
-    public void Validate_InstallPathNullOrWhitespace_ThrowsArgumentException(string installPath)
+    public void Validate_InstallPathNullOrWhitespace_NoException(string installPath)
     {
         var config = new Configinfo
         {
@@ -178,7 +178,8 @@ public void Validate_InstallPathNullOrWhitespace_ThrowsArgumentException(string
             ClientVersion = "1.0.0",
             InstallPath = installPath
         };
-        Assert.Throws<ArgumentException>(() => config.Validate());
+        var exception = Record.Exception(() => config.Validate());
+        Assert.Null(exception);
     }
 
     [Fact]