fix(notification-service): resolve NotificationService-005..009 — explicit TLS modes, per-credential token cache, timeout/throttle, address validation, credential redaction

tests/ScadaLink.NotificationService.Tests/SmtpTlsModeParserTests.cs

@@ -0,0 +1,40 @@
+namespace ScadaLink.NotificationService.Tests;
+
+/// <summary>
+/// NS-005: Tests for parsing the configured SMTP TLS mode into the three-state enum.
+/// </summary>
+public class SmtpTlsModeParserTests
+{
+    [Theory]
+    [InlineData("none", SmtpTlsMode.None)]
+    [InlineData("None", SmtpTlsMode.None)]
+    [InlineData("NONE", SmtpTlsMode.None)]
+    [InlineData("starttls", SmtpTlsMode.StartTls)]
+    [InlineData("StartTLS", SmtpTlsMode.StartTls)]
+    [InlineData("ssl", SmtpTlsMode.Ssl)]
+    [InlineData("SSL", SmtpTlsMode.Ssl)]
+    [InlineData("  starttls  ", SmtpTlsMode.StartTls)]
+    public void Parse_KnownModes_ReturnsExpected(string input, SmtpTlsMode expected)
+    {
+        Assert.Equal(expected, SmtpTlsModeParser.Parse(input));
+    }
+
+    [Theory]
+    [InlineData(null)]
+    [InlineData("")]
+    [InlineData("   ")]
+    public void Parse_NullOrEmpty_DefaultsToStartTls(string? input)
+    {
+        Assert.Equal(SmtpTlsMode.StartTls, SmtpTlsModeParser.Parse(input));
+    }
+
+    [Theory]
+    [InlineData("auto")]
+    [InlineData("tls")]
+    [InlineData("implicit")]
+    public void Parse_UnknownMode_Throws(string input)
+    {
+        // NS-005: an unknown mode must be rejected, not silently treated as Auto.
+        Assert.Throws<ArgumentException>(() => SmtpTlsModeParser.Parse(input));
+    }
+}