From 270f3febb94d64e84c2d99af48ff49733c5c7bc6 Mon Sep 17 00:00:00 2001
From: Oliver Kieselbach <oliver.kieselbach@outlook.com>
Date: Wed, 8 Jul 2026 13:33:46 +0200
Subject: [PATCH] =?UTF-8?q?test(agent):=20fix=20CmTraceLogParser=20BOM=20e?=
 =?UTF-8?q?xpectation=20=E2=80=94=20parser=20is=20BOM-tolerant?=
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The malformed-input theory asserted a BOM-prefixed CMTrace line yields false,
assuming a leading U+FEFF breaks the StartsWith gate. It doesn't: culture-
sensitive string.StartsWith treats U+FEFF as ignorable so the gate passes, and
the unanchored regex matches the "<![LOG[..." body after the BOM — the line
parses (which is desirable; Windows writes a BOM on freshly-opened log lines).

Move the BOM case out of the malformed theory into a dedicated fact that pins
the BOM-tolerant behaviour. Product code unchanged.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .../Monitoring/Ime/CmTraceLogParserTests.cs   | 21 +++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Monitoring/Ime/CmTraceLogParserTests.cs b/src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Monitoring/Ime/CmTraceLogParserTests.cs
index edbc885b..5af372fb 100644
--- a/src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Monitoring/Ime/CmTraceLogParserTests.cs
+++ b/src/Agent/AutopilotMonitor.Agent.V2.Core.Tests/Monitoring/Ime/CmTraceLogParserTests.cs
@@ -26,8 +26,7 @@ namespace AutopilotMonitor.Agent.V2.Core.Tests.Monitoring.Ime
         [InlineData("")]                                       // empty
         [InlineData("   ")]                                    // whitespace only
         [InlineData("<![LOG[truncated line with no closing")]  // truncated / missing fields
-        [InlineData("<![LOG[msg]LOG]!><time=\"06:08:04.8834397\" date=\"2-8-2026\" component=\"C\" context=\"\" type=\"1\" thread=\"1\" file=\"\">")] // leading BOM breaks the StartsWith gate
-        [InlineData("garbage prefix <![LOG[msg]LOG]!><time=\"06:08:04.8834397\" date=\"2-8-2026\" component=\"C\" context=\"\" type=\"1\" thread=\"1\" file=\"\">")] // leading junk
+        [InlineData("garbage prefix <![LOG[msg]LOG]!><time=\"06:08:04.8834397\" date=\"2-8-2026\" component=\"C\" context=\"\" type=\"1\" thread=\"1\" file=\"\">")] // leading junk (non-ignorable) fails the StartsWith gate
         public void TryParseLine_returns_false_without_throwing_for_malformed_input(string line)
         {
             var ok = CmTraceLogParser.TryParseLine(line, out var entry);
@@ -36,6 +35,24 @@ namespace AutopilotMonitor.Agent.V2.Core.Tests.Monitoring.Ime
             Assert.Null(entry);
         }
 
+        // ── Leading BOM → still parses (BOM-tolerant) ────────────────────────
+
+        [Fact]
+        public void TryParseLine_parses_bom_prefixed_line()
+        {
+            // A U+FEFF BOM can prefix the first line of a freshly-opened log. It does NOT break
+            // parsing: string.StartsWith (culture-sensitive) treats U+FEFF as an ignorable
+            // character so the gate passes, and the unanchored regex matches the "<![LOG[..."
+            // body after the BOM. This pins the BOM-tolerant behaviour.
+            var line = "" + CmTraceLine("msg", "06:08:04.8834397", "2-8-2026");
+
+            var ok = CmTraceLogParser.TryParseLine(line, out var entry);
+
+            Assert.True(ok);
+            Assert.NotNull(entry);
+            Assert.Equal("msg", entry.Message);
+        }
+
         // ── Well-formed line → parses ────────────────────────────────────────
 
         [Fact]