From 9bfa1324e55bb7d80dff69114e7d77be403671ed Mon Sep 17 00:00:00 2001
From: TastyHeadphones <76083688+TastyHeadphones@users.noreply.github.com>
Date: Fri, 16 Oct 2026 10:39:13 +0900
Subject: [PATCH] test(feed): regression for backtick identifiers containing
 quotes

Adds a MySQL Syntax.Backticks case for xo/usql#587: an identifier such
as `we'ird` must not open a phantom string, or the following literal's
\\ escapes collapse before the server sees them. The transit grammar
already honors Backticks; this locks the behavior in.

Disclosure: drafted with Grok assistance; I reviewed and tested the change.
---
 feed/backtick_quote_test.go | 46 +++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 feed/backtick_quote_test.go

diff --git a/feed/backtick_quote_test.go b/feed/backtick_quote_test.go
new file mode 100644
index 0000000000..4076876b26
--- /dev/null
+++ b/feed/backtick_quote_test.go
@@ -0,0 +1,46 @@
+package feed
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/xo/dbmeta"
+)
+
+// TestBacktickIdentifierWithQuoteKeepsStringEscapes is the regression for
+// xo/usql#587. Before the transit grammar honored Syntax.Backticks, a MySQL
+// identifier such as `we'ird` opened a phantom string and the following
+// literal's \\ escapes were collapsed before the server saw them.
+func TestBacktickIdentifierWithQuoteKeepsStringEscapes(t *testing.T) {
+	t.Parallel()
+	const q = "select 1 as `we'ird`, hex('a\\\\b');"
+	mysql := dbmeta.Syntax{BlockComments: true, HashComments: true, Backticks: true}
+	p, err := NewParser(Language(mysql, false))
+	if err != nil {
+		t.Fatal(err)
+	}
+	items, err := p.Parse(q)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(items) != 1 {
+		t.Fatalf("items=%d summary=%s", len(items), summary(items))
+	}
+	got := items[0].Expand(func(string) (string, bool) { return "", false })
+	if !strings.Contains(got, `a\\b`) {
+		t.Fatalf("expected a\\\\b preserved in %q", got)
+	}
+	var sawIdent bool
+	for _, part := range items[0].Parts {
+		if part.Kind == QuotedIdentifier {
+			sawIdent = true
+			text := items[0].Text[part.Start:part.End]
+			if !strings.Contains(text, "'") {
+				t.Fatalf("quoted ident missing embedded quote: %q", text)
+			}
+		}
+	}
+	if !sawIdent {
+		t.Fatalf("expected QuotedIdentifier part, parts=%+v", items[0].Parts)
+	}
+}