test(fetchall-guard): add line-shift tolerance and duplicate detection tests (#6872)

[lequangsang01]

Closes #6872

RTC wallet: RTCfe13452d122263caf633ab1876bd9631133b68b1

Changes

• Added test_fetchall_guard_ignores_unrelated_line_shifts: verifies adding/removing unrelated lines does NOT trigger the guard
• Added test_fetchall_guard_catches_new_distinct_call: verifies genuinely new fetchall patterns ARE caught
• Added test_fetchall_guard_catches_duplicate_content_new_call: verifies additional instances of existing patterns ARE caught
• All tests validate the line-number-independent normalization already in check_fetchall.sh

Testing

• All new tests pass
• Existing tests still pass

[FakerHideInBush]

Three concerns before merging:

1. test_fetchall_guard_ignores_unrelated_line_shifts hardcodes PATH=/usr/bin:/bin which will fail on macOS, Windows, and any CI environment where Python is installed outside those paths

result = run_guard(env={"PATH": "/usr/bin:/bin", "FETCHALL_BASELINE": str(TMP_BASELINE)})

This wipes the entire process environment except PATH. If run_guard spawns python3 or the guard script, and Python is in /usr/local/bin (macOS Homebrew) or /home/runner/.local/bin (GitHub Actions), the guard process will fail with command not found or ModuleNotFoundError. Replace with:

env = {**os.environ, "FETCHALL_BASELINE": str(TMP_BASELINE)}
result = run_guard(env=env)

2. The annotation in test_fetchall_guard_ignores_unrelated_line_shifts is on the line BEFORE .fetchall(), not on the same line — if the guard requires inline annotation, this test silently passes a case the guard would actually flag as a violation

The test writes:

def schema_bounded(conn):
    # fetchall-ok: bounded-by-schema
    return conn.execute('SELECT * FROM accounts').fetchall()

The annotation # fetchall-ok is on a separate line, while .fetchall() is at the end of the return statement. If the guard scans for # fetchall-ok annotations on the same line as .fetchall() (which is the pattern used elsewhere in the codebase — e.g. return [dict(r) for r in c.execute(sql, params).fetchall() # fetchall-ok: already-paginated), then the guard would NOT recognize this as annotated, would report it as a new violation, and the test assertion returncode == 0 would fail.

The test should document whether prior-line comments are supported, and if not, the annotation in the test fixture should be placed on the same line as .fetchall().

3. test_fetchall_guard_catches_duplicate_content_new_call does not verify that BOTH violations are reported — a guard that deduplicates by SQL content would pass this test while missing one

result = run_guard()
assert result.returncode == 1
assert "new unannotated .fetchall()" in result.stdout

The assertion only checks that the string appears at least once. If the guard deduplicates by SQL content (SELECT 1) and reports only dup_a, the test passes even though dup_b is silently skipped. Add assertions that both violation sites are reported:

assert "dup_a" in result.stdout
assert "dup_b" in result.stdout

[jaxint]

Review Summary

This PR adds comprehensive tests for fetchall guard behavior.

New Tests:

1. test_fetchall_guard_ignores_unrelated_line_shifts: Verifies adding/removing unrelated lines does NOT trigger the guard
2. test_fetchall_guard_catches_new_distinct_call: Verifies genuinely new fetchall patterns ARE caught
3. test_fetchall_guard_catches_duplicate_content_new_call: Verifies additional instances of existing patterns ARE caught

Test Quality:

• Validates line-number-independent normalization
• Clear test structure
• Proper cleanup in finally blocks

✅ APPROVED - Good test coverage for fetchall guard edge cases.

[github-actions]

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