test(sql): GO batch separators without a semicolon

A GO line with no `;` before it is read as an identifier, so the next
statement lands in an ERROR node and its table is lost. Guards cover
`;`-terminated batches, GO inside a block comment, a column named go,
and GO after a keyword line such as SET NOCOUNT ON.

(cherry picked from commit f00ecc42c9)

tests/test_sql_go_batches.py

@@ -0,0 +1,86 @@
+"""GO batch separators without `;` must not swallow the next statement."""
+from __future__ import annotations
+
+from pathlib import Path
+
+import pytest
+
+pytest.importorskip("tree_sitter_sql")
+
+from graphify.extract import extract_sql  # noqa: E402
+
+TWO_TABLES = "CREATE TABLE dbo.A (id INT){sep}CREATE TABLE dbo.B (id INT){end}"
+
+
+def _labels(path: Path) -> set[str]:
+    return {n["label"].lower() for n in extract_sql(path)["nodes"]}
+
+
+def _run(tmp_path: Path, text: str) -> set[str]:
+    p = tmp_path / "t.sql"
+    p.write_bytes(text.encode())
+    return _labels(p)
+
+
+# bug
+@pytest.mark.parametrize("sep", [
+    "\nGO\n",
+    "\ngo\n",
+    "\nGO 5\n",
+    "\nGO -- next batch\n",
+    "\r\nGO\r\n",
+    "\n  GO  \n",
+])
+def test_go_separated_tables_are_both_found(tmp_path, sep):
+    labels = _run(tmp_path, TWO_TABLES.format(sep=sep, end="\nGO\n"))
+    assert {"dbo.a", "dbo.b"} <= labels
+
+
+# bug
+def test_go_separated_view_reads_its_table(tmp_path):
+    p = tmp_path / "t.sql"
+    p.write_text("CREATE TABLE dbo.A (id INT)\nGO\nCREATE VIEW dbo.V AS SELECT id FROM dbo.A\nGO\n")
+    r = extract_sql(p)
+    label = {n["id"]: n["label"].lower() for n in r["nodes"]}
+    triples = {(label.get(e["source"]), e["relation"], label.get(e["target"])) for e in r["edges"]}
+    assert ("dbo.v", "reads_from", "dbo.a") in triples
+
+
+# bug
+def test_second_table_keeps_its_own_line(tmp_path):
+    p = tmp_path / "t.sql"
+    p.write_text("CREATE TABLE dbo.A (id INT)\nGO\n\nCREATE TABLE dbo.B (id INT)\nGO\n")
+    nodes = {n["label"].lower(): n for n in extract_sql(p)["nodes"]}
+    assert "dbo.b" in nodes
+    assert nodes["dbo.b"].get("source_location") == "L4"
+
+
+# guard
+def test_semicolon_separated_tables_are_both_found(tmp_path):
+    labels = _run(tmp_path, TWO_TABLES.format(sep=";\nGO\n", end=";\nGO\n"))
+    assert {"dbo.a", "dbo.b"} <= labels
+
+
+# guard
+def test_go_inside_block_comment_is_not_a_separator(tmp_path):
+    text = "CREATE TABLE dbo.A (id INT);\n/*\nGO\nCREATE TABLE dbo.Ghost (id INT)\n*/\n"
+    labels = _run(tmp_path, text)
+    assert "dbo.a" in labels
+    assert "dbo.ghost" not in labels
+
+
+# guard
+def test_column_named_go_is_not_a_separator(tmp_path):
+    p = tmp_path / "t.sql"
+    p.write_text("CREATE TABLE dbo.A (id INT);\nCREATE VIEW dbo.V AS SELECT a.id,\n go\nFROM dbo.A a;\n")
+    r = extract_sql(p)
+    label = {n["id"]: n["label"].lower() for n in r["nodes"]}
+    triples = {(label.get(e["source"]), e["relation"], label.get(e["target"])) for e in r["edges"]}
+    assert ("dbo.v", "reads_from", "dbo.a") in triples
+
+
+# guard
+@pytest.mark.parametrize("prev", ["SET NOCOUNT ON", "SET ANSI_NULLS ON", "SET QUOTED_IDENTIFIER ON", "PRINT 'x' AS"])
+def test_go_after_keyword_line_is_a_separator(tmp_path, prev):
+    labels = _run(tmp_path, f"{prev}\nGO\nCREATE TABLE dbo.A (id INT)\nGO\nCREATE TABLE dbo.B (id INT)\nGO\n")
+    assert {"dbo.a", "dbo.b"} <= labels