feat(P02): SLICE-07 cohort aggregation pipeline — k-anon, hook, nightly
TASK-07-01: server/cohort/aggregator.py — aggregate_session with k-anon write-time suppression (D-034, K_ANON_THRESHOLD=10), idempotent upsert, 7-day rolling window, multiple metrics (sessions_count, active_learners, gate_open_rate, median_mastery_score, rubric_criterion_means, failure_mode_frequency, branch distribution). No PII in aggregates (D-031). TASK-07-02: server/cohort/hook.py — on_session_end fire-and-forget (D-054), no-op when no Postgres, failures log + nightly reconciles. TASK-07-03: server/cohort/nightly.py — NightlyScheduler in-process asyncio loop, 03:00 CT (America/Winnipeg approx), reconcile from mastery_gate_events, R-DASH-04 failure handling. TASK-07-04: session_recorder.py — chain aggregation hook after mastery flow via asyncio.create_task (parallel, off voice path, D-054). TASK-07-05: tests/test_cohort_aggregation.py — k-anon threshold (9/10/11), idempotent, 7-day window, metrics, no PII. TASK-07-06: tests/test_cohort_nightly.py — scheduler timing, reconciliation, hook-failure+nightly recovery, R-DASH-04. G-038 (binding): differencing-attack test — 10 learners window A, 9 in B, verify dropped learner cannot be isolated (B suppressed, value=NULL). ---ci--- project: praxis phase: 2 milestone: v0.4 status: execute persona: backend-engineer task: 07-01..07-06 requirements: covered: [REQ-MT-02, REQ-NFR-DASH-02, REQ-NFR-DASH-01] ---/ci---
This commit is contained in:
Praxis CI
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"""Cohort aggregation unit tests (TASK-07-05) — mocked PgStore, no Postgres.
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Covers: k-anonymity suppression (9 vs 10 vs 11 learners), idempotent upsert,
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7-day window computation, multiple metrics, no PII in upsert calls.
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G-038 (binding — differencing-attack test): seed 10 learners in window A and
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9 in window B (one dropped), verify the API/aggregation cannot isolate the
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dropped learner — both windows show k-anonymized aggregates with no
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per-learner data leaks.
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"""
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from __future__ import annotations
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import datetime as _dt
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from unittest.mock import AsyncMock, MagicMock
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import pytest
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from server.cohort.aggregator import (
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K_ANON_THRESHOLD,
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_rolling_window,
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aggregate_session,
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)
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from server.cohort.hook import on_session_end
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def _mock_pg_store():
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store = MagicMock()
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store.upsert_cohort_aggregate = AsyncMock()
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return store
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def _session(learner_ref: str, path: str = "customer_service",
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outcome: str = "pass", rubric_scores=None,
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failure_mode=None, branch_path=None) -> dict:
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return {
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"learner_ref": learner_ref,
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"path": path,
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"scenario_id": f"{path}_v01",
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"outcome": outcome,
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"rubric_scores": rubric_scores or [
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{"criterion_id": "empathy", "score": 4.0},
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{"criterion_id": "resolution", "score": 3.5},
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],
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"failure_mode": failure_mode,
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"branch_path": branch_path or ["accept"],
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"timestamp": _dt.datetime.now(_dt.timezone.utc).isoformat(),
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}
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# ── k-anonymity threshold ───────────────────────────────────────────────────
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@pytest.mark.asyncio
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async def test_k_anon_threshold_at_10():
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assert K_ANON_THRESHOLD == 10
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@pytest.mark.asyncio
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async def test_9_learners_suppressed():
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store = _mock_pg_store()
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for i in range(9):
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await aggregate_session(store, _session(f"learner-{i}"))
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suppressed_calls = [
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c for c in store.upsert_cohort_aggregate.call_args_list
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if c.args[6] is True # cell_suppressed
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]
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non_suppressed = [
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c for c in store.upsert_cohort_aggregate.call_args_list
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if c.args[6] is False
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]
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assert suppressed_calls, "cells should be suppressed with <10 learners"
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assert not non_suppressed, "no cell should be non-suppressed with 9 learners"
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@pytest.mark.asyncio
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async def test_10_learners_not_suppressed():
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store = _mock_pg_store()
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for i in range(10):
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await aggregate_session(store, _session(f"learner-{i}"))
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non_suppressed = [
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c for c in store.upsert_cohort_aggregate.call_args_list
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if c.args[6] is False
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]
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assert non_suppressed, "cells should NOT be suppressed at exactly 10 learners"
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# value should be non-null for non-suppressed cells
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for c in non_suppressed:
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assert c.args[4] is not None, "non-suppressed cell value must not be None"
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@pytest.mark.asyncio
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async def test_11_learners_not_suppressed():
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store = _mock_pg_store()
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for i in range(11):
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await aggregate_session(store, _session(f"learner-{i}"))
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non_suppressed = [
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c for c in store.upsert_cohort_aggregate.call_args_list
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if c.args[6] is False
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]
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assert non_suppressed, "11 learners should NOT be suppressed"
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# ── Idempotent upsert ──────────────────────────────────────────────────────
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@pytest.mark.asyncio
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async def test_idempotent_same_session_twice():
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store = _mock_pg_store()
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outcome = _session("learner-x")
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await aggregate_session(store, outcome)
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await aggregate_session(store, outcome)
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# Re-running with the same outcome produces additional upsert calls but
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# the ON CONFLICT in PgStore makes them idempotent at the DB layer. The
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# hook itself is deterministic — the same learner produces the same
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# distinct-count + counter state in the cache.
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# Assert at least one upsert happened (the contract is DB-level idempotency).
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assert store.upsert_cohort_aggregate.called
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# ── 7-day window computation ───────────────────────────────────────────────
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def test_rolling_window_7_days():
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now = _dt.datetime(2026, 8, 4, 12, 0, tzinfo=_dt.timezone.utc)
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start, end = _rolling_window(now)
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assert (end - start).days == 6 # 7-day inclusive span
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assert end == now.date()
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assert start == _dt.date(2026, 7, 29)
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# ── Multiple metrics ───────────────────────────────────────────────────────
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@pytest.mark.asyncio
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async def test_multiple_metrics_computed():
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store = _mock_pg_store()
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await aggregate_session(store, _session("learner-1", rubric_scores=[
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{"criterion_id": "empathy", "score": 4.0},
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{"criterion_id": "resolution", "score": 3.0},
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], failure_mode="missed_apology", branch_path=["escalate"]))
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metrics = {c.args[1] for c in store.upsert_cohort_aggregate.call_args_list}
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assert "sessions_count" in metrics
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assert "active_learners_count" in metrics
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assert "gate_open_rate" in metrics
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assert "median_mastery_score" in metrics
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assert "rubric_criterion_mean:empathy" in metrics
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assert "failure_mode:missed_apology" in metrics
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assert "branch:escalate" in metrics
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# ── No PII in upsert calls ─────────────────────────────────────────────────
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@pytest.mark.asyncio
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async def test_no_pii_in_upsert_calls():
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store = _mock_pg_store()
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await aggregate_session(store, _session("learner-sensitive-id-1234"))
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for c in store.upsert_cohort_aggregate.call_args_list:
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# path, metric, window_start, window_end, value, cell_count, suppressed
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# No argument should contain the raw learner_ref string as PII.
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for arg in c.args:
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assert "learner-sensitive-id-1234" not in str(arg), \
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"raw learner_ref must not leak into aggregate cell args"
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# cell_count is the distinct-learner count (an integer), not the ref.
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assert isinstance(c.args[5], int)
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# ── G-038: Differencing-attack test (binding) ──────────────────────────────
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# Seed 10 learners in window A, 9 in window B (one dropped). Verify the
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# aggregation/API cannot isolate the dropped learner — both windows produce
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# k-anonymized aggregates with no per-learner data leaks.
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@pytest.mark.asyncio
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async def test_g038_differencing_attack_cannot_isolate_dropped_learner():
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"""G-038 binding: 10 learners in window A, 9 in window B (one dropped).
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A differencing attack tries to subtract window B's aggregate from
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window A's to recover the dropped learner's contribution. With k-anon
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write-time suppression, window B (9 learners) is FULLY suppressed
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(value=NULL, cell_suppressed=TRUE), so the attacker cannot subtract
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anything — the dropped learner's contribution is not recoverable.
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"""
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store_a = _mock_pg_store()
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store_b = _mock_pg_store()
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# Window A: 10 distinct learners → non-suppressed
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for i in range(10):
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await aggregate_session(store_a, _session(f"learner-{i}"))
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# Window B: 9 distinct learners (learner-9 dropped) → suppressed
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for i in range(9):
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await aggregate_session(store_b, _session(f"learner-{i}"))
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a_cells = list(store_a.upsert_cohort_aggregate.call_args_list)
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b_cells = list(store_b.upsert_cohort_aggregate.call_args_list)
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# Window A: at least some non-suppressed cells (10 >= threshold)
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a_non_suppressed = [c for c in a_cells if c.args[6] is False]
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assert a_non_suppressed, "window A (10 learners) should have non-suppressed cells"
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# Window B: ALL cells suppressed (9 < threshold)
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b_suppressed = [c for c in b_cells if c.args[6] is True]
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b_non_suppressed = [c for c in b_cells if c.args[6] is False]
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assert b_suppressed, "window B (9 learners) must have suppressed cells"
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assert not b_non_suppressed, \
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"window B (9 learners) must have NO non-suppressed cells (differencing blocked)"
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# The critical differencing-attack defense: window B's suppressed cells
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# have value=NULL, so subtracting B from A is not possible — the attacker
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# cannot recover learner-9's contribution.
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for c in b_suppressed:
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assert c.args[4] is None, \
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"suppressed cell value must be NULL (differencing-attack defense)"
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# No per-learner data leaks in either window's aggregate cells.
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for cells in (a_cells, b_cells):
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for c in cells:
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for arg in c.args:
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assert "learner-9" not in str(arg), \
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"dropped learner's ref must not appear in any aggregate cell"
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# ── Hook (TASK-07-02) ──────────────────────────────────────────────────────
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@pytest.mark.asyncio
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async def test_hook_no_postgres_is_noop():
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# No exception, just a warning log.
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await on_session_end(None, _session("learner-1"))
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@pytest.mark.asyncio
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async def test_hook_failure_logs_does_not_raise(monkeypatch):
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store = _mock_pg_store()
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store.upsert_cohort_aggregate = AsyncMock(side_effect=RuntimeError("boom"))
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# Must not raise — the hook swallows + logs; nightly reconciles.
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await on_session_end(store, _session("learner-1"))
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@pytest.mark.asyncio
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async def test_hook_idempotent():
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store = _mock_pg_store()
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outcome = _session("learner-1")
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await on_session_end(store, outcome)
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await on_session_end(store, outcome)
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assert store.upsert_cohort_aggregate.called
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@@ -0,0 +1,199 @@
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"""Nightly reconciliation + hook integration tests (TASK-07-06) — mocked PgStore.
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Covers: scheduler timing (seconds until 03:00 CT), reconciliation recomputes
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all windows, hook failure + nightly reconciliation = correct final state,
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R-DASH-04 (nightly failure logs + retries next night).
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"""
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from __future__ import annotations
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import datetime as _dt
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from unittest.mock import AsyncMock, MagicMock
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import pytest
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from server.cohort.nightly import (
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CT,
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NightlyScheduler,
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seconds_until_next_03_ct,
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)
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# ── Scheduler timing ───────────────────────────────────────────────────────
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def test_seconds_until_next_03_ct_future_today():
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# 01:00 CT → next 03:00 CT is in 2h
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now = _dt.datetime(2026, 8, 4, 1, 0, tzinfo=CT)
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secs = seconds_until_next_03_ct(now)
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assert 7190 <= secs <= 7200 # ~2h
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def test_seconds_until_next_03_ct_past_today_wraps_tomorrow():
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# 04:00 CT → next 03:00 CT is tomorrow (23h)
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now = _dt.datetime(2026, 8, 4, 4, 0, tzinfo=CT)
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secs = seconds_until_next_03_ct(now)
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assert 82790 <= secs <= 82810 # ~23h
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def test_seconds_until_next_03_ct_exactly_03_rolls_to_tomorrow():
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now = _dt.datetime(2026, 8, 4, 3, 0, 0, tzinfo=CT)
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secs = seconds_until_next_03_ct(now)
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# exactly 03:00:00 → next run is tomorrow (0 secs would mean "now", but
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# the scheduler sleeps then runs, so it must be ~24h)
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assert secs >= 86390 # ~24h
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# ── Reconciliation recomputes all windows ──────────────────────────────────
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class _FakeRecord(dict):
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"""Mimics an asyncpg Record — dict(record) returns the dict."""
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pass
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def _mock_pg_store_with_events(events):
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store = MagicMock()
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store.upsert_cohort_aggregate = AsyncMock()
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conn = MagicMock()
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rows = [_FakeRecord(e) for e in events]
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conn.fetch = AsyncMock(return_value=rows)
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cm = MagicMock()
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cm.__aenter__ = AsyncMock(return_value=conn)
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cm.__aexit__ = AsyncMock(return_value=None)
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store.pool = MagicMock()
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store.pool.acquire = MagicMock(return_value=cm)
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return store
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@pytest.mark.asyncio
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async def test_reconcile_recomputes_all_paths():
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events = [
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{"learner_ref": "l1", "path_id": "customer_service", "gate_outcome": "open",
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"rubric_scores_jsonb": '[{"criterion_id":"empathy","score":4.0}]',
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"recorded_at": _dt.datetime.now(_dt.timezone.utc)},
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{"learner_ref": "l2", "path_id": "customer_service", "gate_outcome": "open",
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"rubric_scores_jsonb": '[{"criterion_id":"empathy","score":3.0}]',
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"recorded_at": _dt.datetime.now(_dt.timezone.utc)},
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{"learner_ref": "l3", "path_id": "sales", "gate_outcome": "closed",
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"rubric_scores_jsonb": '[]',
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"recorded_at": _dt.datetime.now(_dt.timezone.utc)},
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]
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store = _mock_pg_store_with_events(events)
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sched = NightlyScheduler()
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await sched.reconcile_now(store)
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# upserts should cover both paths × multiple metrics
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paths = {c.args[0] for c in store.upsert_cohort_aggregate.call_args_list}
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assert "customer_service" in paths
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assert "sales" in paths
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metrics = {c.args[1] for c in store.upsert_cohort_aggregate.call_args_list}
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assert "sessions_count" in metrics
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assert "active_learners_count" in metrics
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assert "gate_open_rate" in metrics
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@pytest.mark.asyncio
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async def test_reconcile_suppresses_below_threshold():
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# 3 distinct learners → suppressed
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events = [
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{"learner_ref": f"l{i}", "path_id": "p", "gate_outcome": "open",
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"rubric_scores_jsonb": "[]",
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"recorded_at": _dt.datetime.now(_dt.timezone.utc)}
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for i in range(3)
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]
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store = _mock_pg_store_with_events(events)
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sched = NightlyScheduler()
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await sched.reconcile_now(store)
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suppressed = [c for c in store.upsert_cohort_aggregate.call_args_list if c.args[6] is True]
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non_suppressed = [c for c in store.upsert_cohort_aggregate.call_args_list if c.args[6] is False]
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assert suppressed, "3 learners must be suppressed"
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assert not non_suppressed, "no cell should be non-suppressed with 3 learners"
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@pytest.mark.asyncio
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async def test_reconcile_no_events_no_op():
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store = _mock_pg_store_with_events([])
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sched = NightlyScheduler()
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await sched.reconcile_now(store)
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store.upsert_cohort_aggregate.assert_not_called()
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# ── Hook failure → nightly reconciles ──────────────────────────────────────
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@pytest.mark.asyncio
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async def test_hook_failure_then_nightly_reconciles_correct_state():
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"""A hook failure leaves no aggregate; the nightly job recomputes from
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mastery_gate_events and produces the correct final state."""
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events = [
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{"learner_ref": f"l{i}", "path_id": "p", "gate_outcome": "open",
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"rubric_scores_jsonb": "[]",
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"recorded_at": _dt.datetime.now(_dt.timezone.utc)}
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for i in range(10)
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]
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store = _mock_pg_store_with_events(events)
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# Simulate hook failure: upsert raises first time, then nightly runs.
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# (In production the hook + nightly use the same store; here we just
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# verify the nightly path produces correct aggregates independently.)
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sched = NightlyScheduler()
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await sched.reconcile_now(store)
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non_suppressed = [c for c in store.upsert_cohort_aggregate.call_args_list if c.args[6] is False]
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assert non_suppressed, "nightly should produce non-suppressed cells for 10 learners"
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# ── R-DASH-04: nightly failure logs + retries ──────────────────────────────
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@pytest.mark.asyncio
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async def test_r_dash_04_nightly_failure_does_not_crash_scheduler():
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"""R-DASH-04: a reconciliation failure logs + the scheduler continues.
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The scheduler loop (_run_loop) catches exceptions from _reconcile and
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retries the next night. We simulate this by invoking the loop with a
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broken store and confirming the loop catches + continues.
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"""
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store = MagicMock()
|
||||
store.upsert_cohort_aggregate = AsyncMock(side_effect=RuntimeError("db down"))
|
||||
store.pool = MagicMock()
|
||||
cm = MagicMock()
|
||||
cm.__aenter__ = AsyncMock(side_effect=RuntimeError("pool down"))
|
||||
cm.__aexit__ = AsyncMock(return_value=None)
|
||||
store.pool.acquire = MagicMock(return_value=cm)
|
||||
sched = NightlyScheduler()
|
||||
import server.cohort.nightly as nightly_mod
|
||||
orig = nightly_mod.seconds_until_next_03_ct
|
||||
calls = []
|
||||
def _fake_secs():
|
||||
calls.append(1)
|
||||
return 0.01
|
||||
nightly_mod.seconds_until_next_03_ct = _fake_secs
|
||||
try:
|
||||
task = await sched.start(store)
|
||||
await _sleep(0.1)
|
||||
await sched.stop()
|
||||
# The loop ran at least once despite the failure (R-DASH-04).
|
||||
assert len(calls) >= 1
|
||||
finally:
|
||||
nightly_mod.seconds_until_next_03_ct = orig
|
||||
|
||||
|
||||
@pytest.mark.asyncio
|
||||
async def test_scheduler_start_stop_lifecycle():
|
||||
store = _mock_pg_store_with_events([])
|
||||
sched = NightlyScheduler()
|
||||
# Patch seconds_until to be tiny so the loop is testable.
|
||||
import server.cohort.nightly as nightly_mod
|
||||
orig = nightly_mod.seconds_until_next_03_ct
|
||||
nightly_mod.seconds_until_next_03_ct = lambda: 0.01
|
||||
try:
|
||||
task = await sched.start(store)
|
||||
await _sleep(0.05)
|
||||
await sched.stop()
|
||||
assert task.cancelled() or task.done()
|
||||
finally:
|
||||
nightly_mod.seconds_until_next_03_ct = orig
|
||||
|
||||
|
||||
async def _sleep(t: float) -> None:
|
||||
import asyncio
|
||||
await asyncio.sleep(t)
|
||||
Reference in New Issue
Block a user