/tests/unit/auto-combo-scoring-clamp.test.ts

/**
 * tests/unit/auto-combo-scoring-clamp.test.ts
 *
 * Regression hardening: `calculateScore` summed weighted factors with NO final
 * clamp and NO NaN guard, and `calculateFactors` lower-bounded none of its
 * factors. A single NaN/negative input (bad telemetry, negative quota, negative
 * cost) could yield a NaN or out-of-[0,1] score that sinks a candidate
 * nondeterministically (NaN sorts unpredictably) or distorts ranking.
 *
 * Fix: clamp every factor to [0,1] in calculateFactors and clamp the final
 * score to [0,1] (clamp01 maps non-finite → 0).
 */
import test from "node:test";
import assert from "node:assert/strict";
import {
  calculateScore,
  calculateFactors,
  DEFAULT_WEIGHTS,
} from "../../open-sse/services/autoCombo/scoring.ts";
import type {
  ScoringFactors,
  ProviderCandidate,
} from "../../open-sse/services/autoCombo/scoring.ts";

const ONES: ScoringFactors = {
  quota: 1,
  health: 1,
  costInv: 1,
  latencyInv: 1,
  taskFit: 1,
  stability: 1,
  tierPriority: 1,
  tierAffinity: 1,
  specificityMatch: 1,
  contextAffinity: 1,
  resetWindowAffinity: 1,
  connectionDensity: 1,
};

function candidate(partial: Partial<ProviderCandidate> = {}): ProviderCandidate {
  return {
    provider: "p",
    model: "m",
    quotaRemaining: 100,
    quotaTotal: 100,
    circuitBreakerState: "CLOSED",
    costPer1MTokens: 1,
    p95LatencyMs: 100,
    latencyStdDev: 10,
    errorRate: 0,
    accountTier: "standard",
    quotaResetIntervalSecs: 86400,
    ...partial,
  };
}

test("calculateScore — NaN factor yields a finite [0,1] score (no NaN propagation)", () => {
  const score = calculateScore({ ...ONES, quota: NaN }, DEFAULT_WEIGHTS);
  assert.ok(Number.isFinite(score), "score must be finite even with a NaN factor");
  assert.ok(score >= 0 && score <= 1, `score in [0,1], got ${score}`);
});

test("calculateScore — clamps to [0,1]; all-ones with normalized weights ≈ 1", () => {
  const score = calculateScore(ONES, DEFAULT_WEIGHTS);
  assert.ok(score >= 0 && score <= 1);
  assert.ok(Math.abs(score - 1) < 1e-6, "normalized weights × all-ones ≈ 1");
});

test("calculateScore — negative factors cannot drive the score below 0", () => {
  const score = calculateScore({ ...ONES, costInv: -5, latencyInv: -5 }, DEFAULT_WEIGHTS);
  assert.ok(score >= 0, `score floored at 0, got ${score}`);
});

test("calculateFactors — negative quotaRemaining clamps the quota factor to [0,1]", () => {
  const c = candidate({ quotaRemaining: -50 });
  const f = calculateFactors(c, [c], "default", () => 0.5);
  assert.ok(f.quota >= 0 && f.quota <= 1, `quota factor must be in [0,1], got ${f.quota}`);
});

test("calculateFactors — negative cost cannot push costInv above 1", () => {
  const c = candidate({ costPer1MTokens: -100 });
  const f = calculateFactors(c, [c], "default", () => 0.5);
  assert.ok(f.costInv >= 0 && f.costInv <= 1, `costInv must be in [0,1], got ${f.costInv}`);
});

test("calculateFactors — out-of-range contextAffinity is clamped", () => {
  const c = candidate({ contextAffinity: 5 });
  const f = calculateFactors(c, [c], "default", () => 0.5);
  assert.ok(
    f.contextAffinity >= 0 && f.contextAffinity <= 1,
    `contextAffinity must be in [0,1], got ${f.contextAffinity}`
  );
});

test("calculateFactors — connectionDensity is clamped to [0,1] and NaN-safe", () => {
  // A large pool ((1000-1)/10 = 99.9) must not exceed 1 and skew the weighted score.
  const big = calculateFactors(candidate({ connectionPoolSize: 1000 }), [candidate()], "default", () => 0.5);
  assert.ok(
    big.connectionDensity >= 0 && big.connectionDensity <= 1,
    `connectionDensity must be in [0,1], got ${big.connectionDensity}`
  );
  // A non-finite pool size must map to 0 (clamp01), not propagate NaN into the score.
  const nan = calculateFactors(candidate({ connectionPoolSize: NaN }), [candidate()], "default", () => 0.5);
  assert.ok(
    Number.isFinite(nan.connectionDensity),
    `connectionDensity must be finite (clamp01 maps NaN→0), got ${nan.connectionDensity}`
  );
});