feat: add test channel feature in admin UI

- POST /admin/channels/{id}/test — direct SMTP send via MailKit
- Test button shown only on existing channels (not create)
- Bootstrap modal with recipient email input and spinner
- Inline success/error result inside the modal

Ref: IT-628

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Directory.Packages.props

@@ -31,7 +31,7 @@
         <PackageVersion Include="HrynCo.Common" Version="1.0.0" />
         <PackageVersion Include="HrynCo.RabbitMq" Version="1.0.11" />
 
-        <!-- Testing -->
+        <PackageVersion Include="MailKit" Version="4.11.0" />
         <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
         <PackageVersion Include="coverlet.collector" Version="6.0.4" />
         <PackageVersion Include="xunit" Version="2.9.3" />

HrynCo.NotificationService.Web/Controllers/Admin/AdminChannelsController.cs

@@ -5,8 +5,11 @@ using HrynCo.NotificationService.Services.EmailChannels.Get;
 using HrynCo.NotificationService.Services.EmailChannels.GetAll;
 using HrynCo.NotificationService.Services.EmailChannels.Update;
 using HrynCo.NotificationService.Web.Controllers.Admin.ViewModels;
+using MailKit.Net.Smtp;
+using MailKit.Security;
 using MediatR;
 using Microsoft.AspNetCore.Mvc;
+using MimeKit;
 
 namespace HrynCo.NotificationService.Web.Controllers.Admin;
 
@@ -142,6 +145,46 @@ public class AdminChannelsController : Controller
         return RedirectToAction(nameof(Index));
     }
 
+    // POST /admin/channels/{id}/test
+    [HttpPost("{id:guid}/test")]
+    public async Task<IActionResult> Test(Guid id, [FromBody] TestChannelRequest request, CancellationToken ct)
+    {
+        var result = await _mediator.Send(new GetEmailChannelQuery(id), ct);
+        if (!result.IsSuccess || result.Result is null)
+            return NotFound(new { success = false, message = "Channel not found." });
+
+        if (result.Result.Settings is not SmtpChannelSettings smtp)
+            return BadRequest(new { success = false, message = "Only SMTP channels are supported." });
+
+        try
+        {
+            var message = new MimeMessage();
+            message.From.Add(new MailboxAddress(smtp.FromName, smtp.FromEmail));
+            message.To.Add(MailboxAddress.Parse(request.ToEmail));
+            message.Subject = "✅ Test email from Notification Service";
+            message.Body = new TextPart("plain")
+            {
+                Text = $"This is a test email sent from the Notification Service admin panel.\n\nChannel: {result.Result.ServiceName}\nHost: {smtp.Host}:{smtp.Port}"
+            };
+
+            using var client = new SmtpClient();
+            var secureSocket = smtp.UseSsl ? SecureSocketOptions.SslOnConnect : SecureSocketOptions.StartTlsWhenAvailable;
+            await client.ConnectAsync(smtp.Host, smtp.Port, secureSocket, ct);
+
+            if (!string.IsNullOrWhiteSpace(smtp.Username))
+                await client.AuthenticateAsync(smtp.Username, smtp.Password, ct);
+
+            await client.SendAsync(message, ct);
+            await client.DisconnectAsync(true, ct);
+
+            return Ok(new { success = true, message = $"Test email sent to {request.ToEmail}." });
+        }
+        catch (Exception ex)
+        {
+            return Ok(new { success = false, message = ex.Message });
+        }
+    }
+
     // POST /admin/channels/{id}/delete
     [HttpPost("{id:guid}/delete")]
     [ValidateAntiForgeryToken]
@@ -151,3 +194,5 @@ public class AdminChannelsController : Controller
         return RedirectToAction(nameof(Index));
     }
 }
+
+public record TestChannelRequest(string ToEmail);

HrynCo.NotificationService.Web/HrynCo.NotificationService.Web.csproj

@@ -7,6 +7,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="MailKit" />
     <PackageReference Include="Microsoft.AspNetCore.OpenApi" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Design">
       <PrivateAssets>all</PrivateAssets>

HrynCo.NotificationService.Web/Views/AdminChannels/Edit.cshtml

@@ -134,8 +134,76 @@
         <button type="submit" form="channelForm" class="btn btn-primary">
             <i class="bi bi-floppy me-1"></i> Save
         </button>
+        @if (!Model.IsNew)
+        {
+            <button type="button" class="btn btn-success" data-bs-toggle="modal" data-bs-target="#testModal">
+                <i class="bi bi-send me-1"></i> Test
+            </button>
+        }
         <a href="/admin/channels" class="btn btn-secondary">
             <i class="bi bi-x-lg me-1"></i> Cancel
         </a>
     }
 </form>
+
+@if (!Model.IsNew)
+{
+    <div class="modal fade" id="testModal" tabindex="-1">
+        <div class="modal-dialog modal-dialog-centered">
+            <div class="modal-content">
+                <div class="modal-header">
+                    <h5 class="modal-title"><i class="bi bi-send me-2"></i>Send Test Email</h5>
+                    <button type="button" class="btn-close" data-bs-dismiss="modal"></button>
+                </div>
+                <div class="modal-body">
+                    <label for="testToEmail" class="form-label fw-semibold">Recipient Email</label>
+                    <input type="email" id="testToEmail" class="form-control" placeholder="you@example.com" />
+                    <div id="testResult" class="mt-3" style="display:none"></div>
+                </div>
+                <div class="modal-footer">
+                    <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
+                    <button type="button" class="btn btn-success" id="testSendBtn" onclick="sendTestEmail('@Model.Id')">
+                        <i class="bi bi-send me-1"></i> Send
+                    </button>
+                </div>
+            </div>
+        </div>
+    </div>
+
+    <script>
+        async function sendTestEmail(channelId) {
+            const toEmail = document.getElementById('testToEmail').value.trim();
+            const resultDiv = document.getElementById('testResult');
+            const sendBtn = document.getElementById('testSendBtn');
+
+            if (!toEmail) {
+                resultDiv.style.display = 'block';
+                resultDiv.innerHTML = '<div class="alert alert-warning mb-0">Please enter a recipient email.</div>';
+                return;
+            }
+
+            sendBtn.disabled = true;
+            sendBtn.innerHTML = '<span class="spinner-border spinner-border-sm me-1"></span> Sending…';
+            resultDiv.style.display = 'none';
+
+            try {
+                const resp = await fetch(`/admin/channels/${channelId}/test`, {
+                    method: 'POST',
+                    headers: { 'Content-Type': 'application/json' },
+                    body: JSON.stringify({ toEmail })
+                });
+                const data = await resp.json();
+                resultDiv.style.display = 'block';
+                resultDiv.innerHTML = data.success
+                    ? `<div class="alert alert-success mb-0"><i class="bi bi-check-circle me-1"></i>${data.message}</div>`
+                    : `<div class="alert alert-danger mb-0"><i class="bi bi-x-circle me-1"></i>${data.message}</div>`;
+            } catch (e) {
+                resultDiv.style.display = 'block';
+                resultDiv.innerHTML = `<div class="alert alert-danger mb-0">Request failed: ${e.message}</div>`;
+            } finally {
+                sendBtn.disabled = false;
+                sendBtn.innerHTML = '<i class="bi bi-send me-1"></i> Send';
+            }
+        }
+    </script>
+}