diff --git a/Tests/IsapiDeleteSuccessTests.cs b/Tests/IsapiDeleteSuccessTests.cs
new file mode 100644
index 0000000..0527260
--- /dev/null
+++ b/Tests/IsapiDeleteSuccessTests.cs
@@ -0,0 +1,89 @@
+using Xunit;
+
+namespace HikvisionAttendanceService.Tests;
+
+/// <summary>
+/// Covers delete-success parsing rules used by USER_DELETE confirmation
+/// (regex-based mirror so the test project does not need System.Web.Extensions).
+/// </summary>
+public class IsapiDeleteSuccessTests
+{
+    [Theory]
+    [InlineData("{\"statusCode\":1,\"statusString\":\"OK\",\"subStatusCode\":\"ok\"}", 200, true)]
+    [InlineData("{\n    \"statusCode\": 1,\n    \"statusString\": \"OK\",\n    \"subStatusCode\": \"ok\"\n}", 200, true)]
+    [InlineData("{\"statusCode\":\"1\",\"statusString\":\"OK\",\"subStatusCode\":\"ok\"}", 200, true)]
+    [InlineData("{ \"statusCode\" : 1 , \"statusString\" : \"OK\" }", 200, true)]
+    [InlineData("{\"statusCode\":1,\"subStatusCode\":\"ok\"}", 200, true)]
+    [InlineData("{\"statusCode\":1,\"statusString\":\"OK\"}", 200, true)]
+    [InlineData("{\"statusCode\":1}", 200, false)]
+    [InlineData("{\"statusCode\":4,\"statusString\":\"Invalid Operation\",\"subStatusCode\":\"employeeNoNotExist\"}", 200, false)]
+    [InlineData("{\"statusCode\":1,\"statusString\":\"OK\",\"subStatusCode\":\"ok\"}", 400, false)]
+    public void Confirmed_delete_success_rules(string body, int httpStatus, bool expected)
+    {
+        Assert.Equal(expected, IsConfirmed(body, httpStatus));
+    }
+
+    [Fact]
+    public void Failure_reason_maps_employee_not_found()
+    {
+        Assert.Equal(
+            "Employee was not found on the device",
+            Describe(200, 4, "Invalid Operation", "employeeNoNotExist"));
+    }
+
+    private static bool IsConfirmed(string? body, int httpStatus)
+    {
+        if (httpStatus < 200 || httpStatus >= 300)
+            return false;
+        if (!TryParse(body, out var statusCode, out var statusString, out var subStatusCode))
+            return false;
+        if (statusCode != 1)
+            return false;
+        return string.Equals(statusString, "OK", System.StringComparison.OrdinalIgnoreCase)
+               || string.Equals(subStatusCode, "ok", System.StringComparison.OrdinalIgnoreCase);
+    }
+
+    private static bool TryParse(string? body, out int statusCode, out string statusString, out string subStatusCode)
+    {
+        statusCode = 0;
+        statusString = "";
+        subStatusCode = "";
+        if (string.IsNullOrWhiteSpace(body))
+            return false;
+
+        var mCode = System.Text.RegularExpressions.Regex.Match(body,
+            "\"statusCode\"\\s*:\\s*\"?(?<v>-?\\d+)\"?",
+            System.Text.RegularExpressions.RegexOptions.IgnoreCase);
+        if (mCode.Success)
+            int.TryParse(mCode.Groups["v"].Value, out statusCode);
+
+        var mStr = System.Text.RegularExpressions.Regex.Match(body,
+            "\"statusString\"\\s*:\\s*\"(?<v>[^\"]*)\"",
+            System.Text.RegularExpressions.RegexOptions.IgnoreCase);
+        if (mStr.Success) statusString = mStr.Groups["v"].Value;
+
+        var mSub = System.Text.RegularExpressions.Regex.Match(body,
+            "\"subStatusCode\"\\s*:\\s*\"(?<v>[^\"]*)\"",
+            System.Text.RegularExpressions.RegexOptions.IgnoreCase);
+        if (mSub.Success) subStatusCode = mSub.Groups["v"].Value;
+
+        return statusCode != 0 || statusString.Length > 0 || subStatusCode.Length > 0;
+    }
+
+    private static string Describe(int httpStatus, int statusCode, string statusString, string subStatusCode)
+    {
+        if (httpStatus < 200 || httpStatus >= 300)
+            return "HTTP " + httpStatus;
+        var sub = (subStatusCode ?? "").Trim();
+        if (sub.IndexOf("notExist", System.StringComparison.OrdinalIgnoreCase) >= 0 ||
+            sub.IndexOf("notFound", System.StringComparison.OrdinalIgnoreCase) >= 0 ||
+            sub.Equals("employeeNoNotExist", System.StringComparison.OrdinalIgnoreCase))
+            return "Employee was not found on the device";
+        if (!string.IsNullOrWhiteSpace(statusString) &&
+            !string.Equals(statusString, "OK", System.StringComparison.OrdinalIgnoreCase))
+            return statusString.Trim();
+        if (statusCode != 0 && statusCode != 1)
+            return "Hikvision statusCode=" + statusCode;
+        return "device delete rejected";
+    }
+}