informix-db/tests/test_blob_locator_unit.py
Ryan Malloy 389c32434c Phase 9: smart-LOB BLOB/CLOB locator decoding (Phase 10 deferred for fetch)
SELECT on BLOB or CLOB columns no longer requires raw byte interpretation.
The 72-byte server-side locator is wrapped in a typed BlobLocator or
ClobLocator (frozen dataclass) so the column is recognizable as
"server-side reference, not actual bytes".

Wire-protocol findings:
* Smart-LOB columns DON'T appear with their nominal type codes (102/101)
  in SQ_DESCRIBE. They surface as UDTFIXED (41) with extended_id 10
  (BLOB) or 11 (CLOB) and encoded_length=72 (locator size).
* Retrieving the actual bytes requires SQ_FPROUTINE (103) RPC to
  invoke ifx_lo_open, plus SQ_LODATA (97) for chunked transfer, plus
  another SQ_FPROUTINE for ifx_lo_close. That's a Phase 10 lift —
  roughly 2x the protocol surface of Phase 8.

Server config needed (added to Phase 7 setup):
* sbspace: onspaces -c -S sbspace1 ...
* default sbspace: onmode -wm SBSPACENAME=sbspace1

What ships in Phase 9:
* informix_db.BlobLocator(raw: bytes) — 72-byte frozen wrapper
* informix_db.ClobLocator(raw: bytes) — distinct type, same shape
* Row decoder branch in _resultset.parse_tuple_payload
* Wire constants SQ_LODATA=97, SQ_FPROUTINE=103, SQ_FPARAM=104

Tests:
* 11 unit tests in test_blob_locator_unit.py (no Informix needed) —
  construction, immutability, equality, hash, repr safety, size
  validation.
* 4 integration tests in test_smart_lob.py — fixture seeds via JDBC
  reference client (smart-LOB writes also need deferred protocols).
* RefBlob.java helper in tests/reference/ for seeding via JDBC.

Total: 64 unit + 111 integration = 175 tests.

Locator design note: __repr__ omits the raw bytes (they're opaque to
the client). Same-bytes locators of different families compare
unequal — BlobLocator(x) != ClobLocator(x) — to avoid silent type
confusion.
2026-05-04 13:26:15 -06:00

72 lines
2.1 KiB
Python

"""Phase 9 unit tests — BlobLocator/ClobLocator value semantics.
These don't require Informix; they exercise the typed locator wrappers
directly to verify shape, immutability, equality, and repr safety.
"""
from __future__ import annotations
import dataclasses
import pytest
from informix_db import BlobLocator, ClobLocator
def test_blob_locator_holds_72_bytes() -> None:
raw = bytes(range(72))
loc = BlobLocator(raw=raw)
assert loc.raw == raw
assert len(loc.raw) == 72
def test_clob_locator_holds_72_bytes() -> None:
raw = bytes(reversed(range(72)))
loc = ClobLocator(raw=raw)
assert loc.raw == raw
@pytest.mark.parametrize("size", [0, 1, 71, 73, 144])
def test_locator_rejects_wrong_size(size: int) -> None:
"""The constructor enforces exactly 72 bytes."""
with pytest.raises(ValueError, match="72 bytes"):
BlobLocator(raw=bytes(size))
with pytest.raises(ValueError, match="72 bytes"):
ClobLocator(raw=bytes(size))
def test_locator_is_frozen() -> None:
"""Instances are immutable per ``frozen=True`` dataclass decorator."""
loc = BlobLocator(raw=bytes(72))
with pytest.raises(dataclasses.FrozenInstanceError):
loc.raw = b"x" * 72 # type: ignore[misc]
def test_blob_and_clob_locator_are_distinct_types() -> None:
"""Same-bytes locators of different families compare unequal."""
raw = bytes(72)
blob = BlobLocator(raw=raw)
clob = ClobLocator(raw=raw)
assert blob != clob
assert not isinstance(blob, ClobLocator)
assert not isinstance(clob, BlobLocator)
def test_locator_equality() -> None:
"""Same bytes + same family → equal."""
raw = b"\x01\x02\x03" + bytes(69)
a = BlobLocator(raw=raw)
b = BlobLocator(raw=raw)
assert a == b
assert hash(a) == hash(b)
def test_locator_repr_omits_raw_bytes() -> None:
"""``repr`` doesn't leak the opaque locator bytes (no use to user)."""
raw = b"\xde\xad\xbe\xef" + bytes(68)
loc = BlobLocator(raw=raw)
r = repr(loc)
assert "BlobLocator" in r
assert "deadbeef" not in r.lower()
assert raw.hex() not in r