tests/test_context.py

from __future__ import annotations

import json
from pathlib import Path

import pytest

from shiftedx_bench.context import ContextSpec, build_context_case, expand_context_config
from shiftedx_bench.boundary import probe_context_boundary
from shiftedx_bench.holdout import derive_holdout_config


class CharTokenizer:
    fingerprint = "char-tokenizer-v1"

    def encode(self, text: str) -> list[int]:
        return [ord(value) for value in text]

    def decode(self, token_ids: list[int]) -> str:
        return "".join(chr(value) for value in token_ids)

    def render_chat(self, messages):
        return "".join(f"<{item['role']}>\n{item['content']}\n" for item in messages) + "<assistant>\n"

    def token_offset(self, rendered_text: str, substring: str) -> int:
        value = rendered_text.index(substring)
        return len(self.encode(rendered_text[:value]))


def test_smoke_plan_has_expected_coverage():
    root = Path(__file__).resolve().parents[1]
    config = json.loads((root / "configs/context-smoke-v1.json").read_text())
    specs = expand_context_config(config)
    assert len(specs) == 19
    assert {spec.target_tokens for spec in specs} >= {4096, 32768, 131072, 260096}
    assert {spec.query_placement for spec in specs} == {"before", "after"}


def test_quant_gate_is_bounded_but_multidimensional():
    root = Path(__file__).resolve().parents[1]
    config = json.loads((root / "configs/context-quant-gate-v1.json").read_text())
    specs = expand_context_config(config)
    assert len(specs) == 15
    assert sum(spec.target_tokens for spec in specs) == 372736
    assert {spec.target_tokens for spec in specs} == {4096, 16384, 65536, 131072}
    assert {spec.family for spec in specs} == {
        "single_key", "binding", "latest_record", "multi_hop", "semantic", "state_tracking"
    }
    assert {spec.query_placement for spec in specs} == {"before", "after"}


def test_max_window_sentinel_is_explicitly_separate():
    root = Path(__file__).resolve().parents[1]
    config = json.loads((root / "configs/context-max-window-v1.json").read_text())
    specs = expand_context_config(config)
    assert len(specs) == 1
    assert specs[0].target_tokens == 260096
    assert specs[0].family == "single_key"


@pytest.mark.parametrize(
    "family",
    ["single_key", "binding", "latest_record", "multi_hop", "semantic", "state_tracking"],
)
@pytest.mark.parametrize("position", [0.01, 0.5, 0.99])
def test_context_is_exact_and_positioned(family: str, position: float):
    spec = ContextSpec("suite", "matrix", family, 12000, position, 173)
    case = build_context_case(spec, CharTokenizer())
    assert case.metadata["actual_rendered_tokens"] == 12000
    assert abs(case.metadata["actual_primary_position"] - position) <= 0.003
    assert set(case.expected) >= {"start_sentinel", "end_sentinel", "record"}


def test_rejects_duplicate_identifiers():
    config = {
        "suite_id": "x",
        "matrices": [{
            "name": "m", "families": ["single_key", "single_key"], "lengths": [4096],
            "positions": [0.5], "seeds": [1]
        }],
    }
    with pytest.raises(ValueError, match="duplicate"):
        expand_context_config(config)


def test_holdout_derivation_is_stable_and_release_specific():
    template = {
        "suite_id": "x", "context_window": 8192, "reserved_output_tokens": 512,
        "matrices": [{"name":"m","families":["single_key"],"lengths":[4096],"positions":[.5],"seeds":[1,2]}],
    }
    first = derive_holdout_config(template, "a sufficiently long private key", "r1")
    second = derive_holdout_config(template, "a sufficiently long private key", "r1")
    third = derive_holdout_config(template, "a sufficiently long private key", "r2")
    assert first == second
    assert first["matrices"][0]["seeds"] != third["matrices"][0]["seeds"]
    assert "private key" not in str(first)


def test_rejects_prompt_beyond_reserved_output_budget():
    config = {
        "suite_id":"x", "context_window":4096, "reserved_output_tokens":512,
        "matrices":[{"name":"m","families":["single_key"],"lengths":[3585],"positions":[.5],"seeds":[1]}],
    }
    with pytest.raises(ValueError, match="exceeds"):
        expand_context_config(config)


def test_boundary_probe_requires_explicit_server_rejection():
    class RejectingClient:
        def complete(self, payload, stream=False):
            raise RuntimeError("HTTP 400: context window exceeded")

    result = probe_context_boundary(
        client=RejectingClient(), tokenizer=CharTokenizer(), model="m",
        context_window=4096, reserved_output_tokens=512,
    )
    assert result["passed"]