/** * Tests for the margin arithmetic. * * This is the most load-bearing pure code in the project: every dashboard * figure, every idle-capacity alert and every answer an agent gives resolves * through these functions. An error here is an error everywhere, and it would * be a quiet one — wrong numbers still look like numbers. * * The cases below are chosen to pin the *decisions*, not merely the * implementation. Several would pass under a naive version that is wrong in a * way that flatters the business, which is precisely why they exist. */ import { strict as assert } from 'node:assert'; import { describe, it } from 'node:test'; import { aggregateMargin, breakEvenPricePerGpuHourCents, computeMargin, formatCents, } from '../src/margin'; describe('computeMargin', () => { it('charges cost against the FULL commitment, not only the hours sold', () => { // The decision the whole product rests on. A naive implementation charges // only the allocated share and reports this block as profitable, when in // fact it loses money: the unsold hours were already paid for. const result = computeMargin( { gpuHours: 1000, costPerGpuHourCents: 100 }, [{ gpuHours: 500, pricePerGpuHourCents: 150 }], ); assert.equal(result.costCents, 100_000, 'cost must cover all 1000 hours'); assert.equal(result.revenueCents, 75_000); assert.equal(result.grossMarginCents, -25_000, 'this block is underwater'); // Under the naive treatment: cost 500×100 = 50,000 against revenue 75,000, // reporting +25,000 — a sign error on the thing that matters most. assert.ok(result.grossMarginCents < 0); }); it('reports utilisation and idle hours', () => { const r = computeMargin({ gpuHours: 1000, costPerGpuHourCents: 100 }, [ { gpuHours: 700, pricePerGpuHourCents: 200 }, ]); assert.equal(r.allocatedGpuHours, 700); assert.equal(r.idleGpuHours, 300); assert.equal(r.utilisation, 0.7); }); it('sums several allocations against one commitment', () => { const r = computeMargin({ gpuHours: 1000, costPerGpuHourCents: 100 }, [ { gpuHours: 400, pricePerGpuHourCents: 200 }, { gpuHours: 300, pricePerGpuHourCents: 250 }, ]); assert.equal(r.allocatedGpuHours, 700); assert.equal(r.revenueCents, 400 * 200 + 300 * 250); }); it('counts internal consumption as cost with no revenue', () => { // Research burn is a zero-price allocation. Leaving it out would overstate // available capacity; pricing it at anything but zero would invent revenue. const r = computeMargin({ gpuHours: 1000, costPerGpuHourCents: 100 }, [ { gpuHours: 600, pricePerGpuHourCents: 200 }, { gpuHours: 200, pricePerGpuHourCents: 0 }, ]); assert.equal(r.allocatedGpuHours, 800); assert.equal(r.revenueCents, 120_000, 'the internal 200 hours earn nothing'); assert.equal(r.idleGpuHours, 200); }); it('clamps idle at zero when capacity is deliberately oversubscribed', () => { // Selling beyond 100% is a real policy, not a data-entry error. Negative // idle hours would be nonsense to display. const r = computeMargin({ gpuHours: 1000, costPerGpuHourCents: 100 }, [ { gpuHours: 1200, pricePerGpuHourCents: 150 }, ]); assert.equal(r.idleGpuHours, 0); assert.equal(r.utilisation, 1.2, 'utilisation itself is not clamped — it is the signal'); }); it('returns null rather than dividing by zero on an empty book', () => { const r = computeMargin({ gpuHours: 1000, costPerGpuHourCents: 100 }, []); assert.equal(r.revenueCents, 0); assert.equal(r.grossMarginCents, -100_000); assert.equal(r.grossMarginPct, null, 'no revenue means no percentage, not Infinity'); assert.equal(r.marginPerAllocatedGpuHourCents, null); }); it('handles a zero-hour commitment without producing NaN', () => { const r = computeMargin({ gpuHours: 0, costPerGpuHourCents: 100 }, []); assert.equal(r.utilisation, 0); assert.ok(!Number.isNaN(r.utilisation)); }); it('keeps money in whole cents', () => { // Fractional hours are normal; fractional cents are not. A dashboard that // renders 1234.9999999 has lost the plot. const r = computeMargin({ gpuHours: 0.1, costPerGpuHourCents: 3 }, [ { gpuHours: 0.1, pricePerGpuHourCents: 7 }, ]); assert.ok(Number.isInteger(r.costCents)); assert.ok(Number.isInteger(r.revenueCents)); }); }); describe('breakEvenPricePerGpuHourCents', () => { it('prices the REMAINING hours, not the whole block', () => { // Half a 1000-hour block at 100c cost is sold at 120c: 60,000 of 100,000 // recovered, 40,000 outstanding across 500 remaining hours = 80c. const price = breakEvenPricePerGpuHourCents({ gpuHours: 1000, costPerGpuHourCents: 100 }, [ { gpuHours: 500, pricePerGpuHourCents: 120 }, ]); assert.equal(price, 80); }); it('falls as more of the block sells', () => { const commitment = { gpuHours: 1000, costPerGpuHourCents: 100 }; const early = breakEvenPricePerGpuHourCents(commitment, [ { gpuHours: 200, pricePerGpuHourCents: 120 }, ])!; const later = breakEvenPricePerGpuHourCents(commitment, [ { gpuHours: 800, pricePerGpuHourCents: 120 }, ])!; assert.ok(later < early, 'a mostly-sold block is cheaper to break even on'); }); it('returns zero once cost is covered — further sales are pure upside', () => { const price = breakEvenPricePerGpuHourCents({ gpuHours: 1000, costPerGpuHourCents: 100 }, [ { gpuHours: 500, pricePerGpuHourCents: 300 }, ]); // Not a negative price, which would be meaningless to show a seller. assert.equal(price, 0); }); it('returns null when nothing is left to sell', () => { const price = breakEvenPricePerGpuHourCents({ gpuHours: 1000, costPerGpuHourCents: 100 }, [ { gpuHours: 1000, pricePerGpuHourCents: 150 }, ]); assert.equal(price, null, 'no remaining hours means no break-even price, not Infinity'); }); }); describe('aggregateMargin', () => { it('sums cents rather than averaging percentages', () => { // A tiny block at a wonderful margin next to a huge one at a terrible // margin. Averaging the two percentages would report roughly break-even; // the truth is a large loss dominated by the big block. const result = aggregateMargin([ { commitment: { gpuHours: 10, costPerGpuHourCents: 100 }, allocations: [{ gpuHours: 10, pricePerGpuHourCents: 1000 }], }, { commitment: { gpuHours: 10_000, costPerGpuHourCents: 100 }, allocations: [{ gpuHours: 5_000, pricePerGpuHourCents: 110 }], }, ]); assert.equal(result.costCents, 10 * 100 + 10_000 * 100); assert.equal(result.revenueCents, 10 * 1000 + 5_000 * 110); assert.ok(result.grossMarginCents < 0, 'the big block dominates'); // The naive mean of +90% and -45% is about +22%, which is the wrong sign. assert.ok(result.grossMarginPct! < 0); }); it('is empty-safe', () => { const r = aggregateMargin([]); assert.equal(r.costCents, 0); assert.equal(r.grossMarginPct, null); assert.equal(r.utilisation, 0); }); }); describe('formatCents', () => { it('renders whole currency from integer cents', () => { assert.equal(formatCents(123_456), '$1,234.56'); assert.equal(formatCents(0), '$0.00'); }); it('renders negatives, which is the case that matters', () => { assert.ok(formatCents(-5000).includes('50')); }); });