harden(vtag): exclude backslash from passthrough capture + parity tests (A review)

2026-06-07 15:31:54 -04:00
parent 08d7477860
commit b73ce75402
3 changed files with 62 additions and 1 deletions
@@ -76,4 +76,26 @@ public sealed class PassthroughScriptTests
        PassthroughScript.TryMatch(source, out var tag).ShouldBeFalse();
        tag.ShouldBe(string.Empty);
    }
+
+    /// <summary>
+    /// A tag literal containing a backslash escape (C# source <c>"a\\b"</c> → runtime name
+    /// <c>a\b</c>) does NOT match the passthrough pattern — it falls through to Roslyn, which
+    /// interprets the escape and resolves the correct dependency key.  Capturing the raw source
+    /// text <c>a\\b</c> would produce a wrong-result silent miss against the key <c>a\b</c>.
+    /// </summary>
+    [Fact]
+    public void Rejects_tag_literal_containing_backslash_escape()
+    {
+        // C# literal "return ctx.GetTag(\"a\\\\b\").Value;" → script source contains: a\\b (two chars: backslash + b)
+        PassthroughScript.TryMatch("return ctx.GetTag(\"a\\\\b\").Value;", out var tag).ShouldBeFalse();
+        tag.ShouldBe(string.Empty);
+    }
+
+    /// <summary>A plain dotted tag name (no backslash) still matches — the fix is additive only.</summary>
+    [Fact]
+    public void Matches_plain_dotted_tag_after_backslash_fix()
+    {
+        PassthroughScript.TryMatch("return ctx.GetTag(\"Site1.Area.Tag\").Value;", out var tag).ShouldBeTrue();
+        tag.ShouldBe("Site1.Area.Tag");
+    }
 }