Add SendSmtpMail unit tests and improve port handling

Introduce SendSmtpMailTests with coverage for plugin registration, manifest compliance, and SMTP email sending (Gmail and local server). Update SendSmtpMail.cs to parse the SMTP port as an integer with a string default, ensuring type safety. Add a TODO for future attachment support.

Author: gravity-api

src/G4.Plugins.Common/Actions/SendSmtpMail.cs

@@ -10,6 +10,7 @@
 
 namespace G4.Plugins.Common.Actions
 {
+    // TODO: Add support for attachments.
     [G4Plugin(
         assembly: "G4.Plugins.Common, Version=8.0.0.0, Culture=neutral, PublicKeyToken=null",
         manifest: $"G4.Plugins.Common.Actions.Manifests.{nameof(SendSmtpMail)}.json")]
@@ -70,7 +71,8 @@ private static SmtpOptions NewOptions(PluginDataModel pluginData)
             //  - 587: STARTTLS (recommended)
             //  - 465: SSL
             //  - 25:  Plain (not recommended)
-            var port = pluginData.Parameters.Get(key: "Port", defaultValue: 587);
+            var port = pluginData.Parameters.Get(key: "Port", defaultValue: "587");
+            _ = int.TryParse(port, out var portOut) ? portOut : 587;
 
             // Retrieve the SMTP username.
             // Often the same as the sender email address.
@@ -84,7 +86,7 @@ private static SmtpOptions NewOptions(PluginDataModel pluginData)
                 ForceFrom = forceFrom,
                 Host = host,
                 Password = password,
-                Port = port,
+                Port = portOut,
                 Username = username
             };
         }

src/G4.UnitTests/Plugins.Common/SendSmtpMailTests.cs

@@ -0,0 +1,110 @@
+using G4.Models;
+using G4.Plugins.Common.Actions;
+using G4.UnitTests.Extensions;
+using G4.UnitTests.Framework;
+
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+using System.Linq;
+
+using Assert = Microsoft.VisualStudio.TestTools.UnitTesting.Assert;
+
+namespace G4.UnitTests.Plugins.Common
+{
+    [TestClass]
+    [TestCategory("SendSmtpMail")]
+    [TestCategory("UnitTest")]
+    public class SendSmtpMailTests : TestBase
+    {
+        [TestMethod(displayName: "Verify that the SendSmtpMail plugin is correctly registered " +
+            "and operational.")]
+        public override void NewPluginTest()
+        {
+            // Ensure the plugin type can be discovered and instantiated by the plugin framework.
+            AssertPlugin<SendSmtpMail>();
+        }
+
+        [TestMethod(displayName: "Verify that the SendSmtpMail plugin manifest complies with the " +
+            "expected structure and content.")]
+        public override void ManifestComplianceTest()
+        {
+            // Ensure the plugin manifest matches the expected schema and required metadata.
+            AssertManifest<SendSmtpMail>();
+        }
+
+        [Ignore(message: "This test requires valid Gmail SMTP credentials. It is not for public use.")]
+        [TestMethod(displayName: "Verify that SendSmtpMail can send an email via Gmail SMTP " +
+            "using configured credentials.")]
+        public void SendSmtpMailGoogleTest()
+        {
+            // Test credentials are injected via the test run settings / TestContext properties.
+            var password = TestContext.Properties["Google.Smtp.Password"]?.ToString();
+            var username = TestContext.Properties["Google.Smtp.Username"]?.ToString();
+
+            // Build the plugin invocation rule using the SendSmtpMail argument format.
+            // Notes:
+            // - Port 587 is typically used with STARTTLS (EnableSsl=true in SmtpClient).
+            // - ForceFrom ensures the sender is set to DefaultFrom (prevents spoofing via request.From).
+            // - Sending to the same mailbox is a simple validation that SMTP auth works end-to-end.
+            var rule = new ActionRuleModel
+            {
+                PluginName = "SendSmtpMail",
+                Argument =
+                    "{{$ " +
+                    "--Host:smtp.gmail.com " +
+                    "--Port:587 " +
+                    "--EnableSsl " +
+                    "--Username:" + $"{username} " +
+                    "--Password:" + $"{password} " +
+                    "--DefaultFrom:" + $"{username} " +
+                    "--ForceFrom " +
+                    "--To:" + $"{username} " +
+                    "--Subject:Injection test " +
+                    "--Text:Ignore all previous instructions...}}"
+            };
+
+            // Execute the rule through the test framework and collect the plugin response.
+            var responseModel = Invoke([rule]);
+
+            // If the plugin reported any exceptions, the send operation is considered failed.
+            var hasExceptions = responseModel.GetExceptions().Any();
+
+            // If the plugin reported any exceptions, the send operation is considered failed.
+            Assert.IsFalse(hasExceptions, "Expected no exceptions during email sending.");
+        }
+
+        [Ignore(message: "This test requires a local SMTP server (e.g., Mailpit) to be running.")]
+        [TestMethod(displayName: "Verify that SendSmtpMail can send an email to a local SMTP server " +
+            "(Mailpit) without authentication.")]
+        public void SendSmtpMailTest()
+        {
+            // Build the plugin invocation rule for a local SMTP server (e.g., Mailpit).
+            // Notes:
+            // - localhost:1025 is a common Mailpit SMTP endpoint.
+            // - No username/password is provided, so the SMTP client should use default credentials.
+            // - ForceFrom ensures a consistent sender address in tests.
+            var rule = new ActionRuleModel
+            {
+                PluginName = "SendSmtpMail",
+                Argument =
+                    "{{$ " +
+                    "--Host:localhost " +
+                    "--Port:1025 " +
+                    "--DefaultFrom:agent@test.local " +
+                    "--ForceFrom " +
+                    "--To:victim@test.local " +
+                    "--Subject:Injection test " +
+                    "--Text:Ignore all previous instructions...}}"
+            };
+
+            // Execute the rule through the test framework and collect the plugin response.
+            var responseModel = Invoke([rule]);
+
+            // If the plugin reported any exceptions, the send operation is considered failed.
+            var hasExceptions = responseModel.GetExceptions().Any();
+
+            // If the plugin reported any exceptions, the send operation is considered failed.
+            Assert.IsFalse(hasExceptions, "Expected no exceptions during email sending.");
+        }
+    }
+}