const { pool, constant, d, add, subtract, multiply, divide, bonusAdd, bonusSubtract, negative, explodeAbove, explodeUnder, keepHigh, keepLow, againAbove, againUnder, thresholdHigh, thresholdLow, repeat } = require('../src/dice.js') const defaultNumberRolls = 500 const defaultError = 0.2 const isWithinError = (value, expected, error) => { if (expected < 0) { value *= -1 expected *= -1 } const margin = expected * error return value >= expected - margin && value <= expected + margin } expect.extend({ toBeOnAverage(received, expected, error = defaultError) { const average = received.reduce(plus) / received.length const pass = isWithinError(average, expected, error) return { pass, message: () => ( `expected average to${pass ? ' not ' : ' '}be around ${expected} (error: ${error * 100}%), got ${average}` ) } }, toBeBetween(received, low, high) { const pass = received.reduce((allOk, value) => { return allOk && value >= low && value <= high }, true) return { pass, message: () => ( `expected all to${pass ? ' not ' : ' '}be between ${low} and ${high}` ) } }, toAllBe(received, expected) { const pass = received.reduce((allOk, value) => { return allOk && value === expected }, true) return { pass, message: () => ( `expected all to${pass ? ' not ' : ' '}be equal to ${expected}` ) } }, toHaveVariance(received, expected, error = defaultError) { const average = received.reduce(plus) / received.length const variance = received.map((value) => (Math.pow(value - average, 2))) .reduce(plus) / (received.length - 1) const pass = isWithinError(variance, expected, error) return { pass, message: () => ( `expected variance to${pass ? ' not ' : ' '}be around ${expected} (error: ${error * 100}%), got ${variance}` ) } } }) const plus = (a, b) => a + b const times = (a, b) => a * b const rollForTest = (die, numberRolls) => { let pools = [] let rolls = [] for (let i = 0; i < numberRolls; i++) { let rolled = pool(die) pools.push(rolled) rolls.push(rolled.reduce(plus, 0)) } return { pools, rolls } } const testDie = (die, testSpecs, numberRolls = defaultNumberRolls) => { let { pools, rolls } = rollForTest(die, numberRolls) if ('diceCount' in testSpecs) { it(`rolls ${testSpecs.diceCount} dice`, () => { expect(pools.map((pool) => (pool.length))).toAllBe(testSpecs.diceCount) }) } if ('variableDiceCount' in testSpecs) { const {min, max} = testSpecs.variableDiceCount it(`rolls between ${min} and ${max} dice`, () => { expect(pools.map((pool) => (pool.length))).toBeBetween(min, max) }) } if ('average' in testSpecs) { let { average, error } = testSpecs.average it(`has an expected value of ${average}`, () => { expect(rolls).toBeOnAverage(average, error) }) } if ('variance' in testSpecs) { let { variance, error } = testSpecs.variance it(`has a variance of ${variance}`, () => { expect(rolls).toHaveVariance(variance, error) }) } if ('bounds' in testSpecs) { let { low, high, expectLow, expectHigh } = testSpecs.bounds it(`rolls between ${low} and ${high}`, () => { expect(rolls).toBeBetween(low, high) }) if (expectLow) { it('attains its minimum', () => { expect(rolls).toContain(low) }) } if (expectHigh) { it('attains its maximum', () => { expect(rolls).toContain(high) }) } } } const basicDieTestSpecs = (number, sides, negative = false) => { const multiplier = negative ? -1 : 1 const low = negative ? -(number * sides) : number const high = negative ? -number : number * sides const expectExtrema = number * sides < 50 return { diceCount: number, average: { average: (number * (sides + 1)) / 2 * multiplier }, variance: { variance: (number * (sides * sides - 1)) / 12 }, bounds: { low: low, high: high, expectLow: expectExtrema, expectHigh: expectExtrema } } } const combinedDiceTestSpecs = (dieSpecs) => { const individualTestSpecs = dieSpecs.map(spec => ( basicDieTestSpecs(spec.number, spec.sides, spec.negative) )) const combineSpecField = (fieldGetter) => { return individualTestSpecs.reduce((total, spec) => { return total + fieldGetter(spec) }, 0) } const expectExtrema = dieSpecs.map(spec => (Math.pow(spec.sides, spec.number))) .reduce(times) < 50 return { diceCount: combineSpecField(spec => (spec.diceCount)), average: { average: combineSpecField(spec => (spec.average.average)) }, variance: { variance: combineSpecField(spec => (spec.variance.variance)) }, bounds: { low: combineSpecField(spec => (spec.bounds.low)), high: combineSpecField(spec => (spec.bounds.high)), expectLow: expectExtrema, expectHigh: expectExtrema } } } const describeBasicDie = (number, sides, numberRolls = defaultNumberRolls, neg = false) => { describe(`${number}d${sides}`, () => { let die = d(constant(number), constant(sides)) if (neg) { die = negative(die) } testDie(die, basicDieTestSpecs(number, sides, neg), numberRolls) }) } const getDieString = diceSpecs => ( diceSpecs.reduce((string, spec, index) => ( string + `${spec.number}d${spec.sides}` + (index < diceSpecs.length - 1 ? (diceSpecs[index + 1].negative ? ' - ' : ' + ') : '') ), '') ) const combineDiceSpecs = diceSpecs => ( diceSpecs.slice(1).reduce((die, spec) => { const combinator = spec.negative ? subtract : add return combinator(die, d(constant(spec.number), constant(spec.sides))) }, d(constant(diceSpecs[0].number), constant(diceSpecs[0].sides))) ) const describeCompoundDice = (diceSpecs, numberRolls = defaultNumberRolls) => { const dieString = getDieString(diceSpecs) const die = combineDiceSpecs(diceSpecs) describe(dieString, () => testDie(die, combinedDiceTestSpecs(diceSpecs), numberRolls)) } describe('constant', () => { describe('1', () => { const die = constant(1) testDie(die, { diceCount: 1, average: { average: 1 }, variance: { variance: 0 }, bounds: { low: 1, high: 1, expectLow: true, } }, 10) }) describe('10', () => { const die = constant(10) testDie(die, { diceCount: 1, average: { average: 10 }, variance: { variance: 0 }, bounds: { low: 10, high: 10, expectLow: true, } }, 10) }) describe('-5', () => { const die = constant(-5) testDie(die, { diceCount: 1, average: { average: -5 }, variance: { variance: 0 }, bounds: { low: -5, high: -5, expectLow: true, } }, 10) }) }) describe('basic dice', () => { describeBasicDie(1, 6) describeBasicDie(0, 6) describeBasicDie(2, 8, 500) describeBasicDie(20, 1) }) describe('add', () => { describeCompoundDice([ { number: 1, sides: 6 }, { number: 1, sides: 4 } ]) describeCompoundDice([ { number: 3, sides: 6 }, { number: 2, sides: 8 }, { number: 1, sides: 1 } ]) }) describe('subtract', () => { describeCompoundDice([ { number: 1, sides: 6 }, { number: 1, sides: 4, negative: true } ]) describe('3d6 - 2d8 - 1d1', () => { const diceSpecs = [ { number: 3, sides: 6 }, { number: 2, sides: 8, negative: true }, { number: 1, sides: 1, negative: true } ] const die = combineDiceSpecs(diceSpecs) const testSpecs = combinedDiceTestSpecs(diceSpecs) testSpecs.average.error = 1 describe('3d6 - 2d8 - 1d1', () => testDie(die, testSpecs, 700)) }) }) describe('multiply', () => { describe('1d6 * 3', () => { const die = multiply(d(constant(1), constant(6)), constant(3)) testDie(die, { diceCount: 1, average: { average: 10.5 }, variance: { variance: 26.25 }, bounds: { low: 3, high: 18, expectLow: true, expectHigh: true } }) }) }) describe('divide', () => { describe('1d8 / 2', () => { const die = divide(d(constant(1), constant(8)), constant(2)) testDie(die, { diceCount: 1, average: { average: 2 }, variance: { variance: 1.5 }, bounds: { low: 0, high: 4, expectLow: true, expectHigh: true } }) }) }) describe('bonusAdd', () => { describe('1d20+3', () => { const die = bonusAdd(d(constant(1), constant(20)), constant(3)) testDie(die, { diceCount: 1, average: { average: 13.5 }, variance: { variance: 33.25 }, bounds: { low: 4, high: 23, expectLow: true, expectHigh: true } }) }) describe('3d4+1', () => { const die = bonusAdd(d(constant(3), constant(4)), constant(1)) testDie(die, { diceCount: 3, average: { average: 10.5 }, variance: { variance: 3.75 }, bounds: { low: 6, high: 15, expectLow: true, expectHigh: true } }) }) describe('2d6+1d6', () => { const die = bonusAdd(d(constant(2), constant(6)), d(constant(1), constant(6))) testDie(die, { diceCount: 2, average: { average: 14 }, variance: { variance: 11.67 }, bounds: { low: 4, high: 24, expectLow: false, expectHigh: false } }) }) }) describe('bonusSubtract', () => { describe('1d20-3', () => { const die = bonusSubtract(d(constant(1), constant(20)), constant(3)) testDie(die, { diceCount: 1, average: { average: 7.5 }, variance: { variance: 33.25 }, bounds: { low: -2, high: 17, expectLow: true, expectHigh: true } }) }) describe('3d4-1', () => { const die = bonusSubtract(d(constant(3), constant(4)), constant(1)) testDie(die, { diceCount: 3, average: { average: 4.5 }, variance: { variance: 3.75 }, bounds: { low: 0, high: 9, expectLow: true, expectHigh: true } }) }) }) describe('negative', () => { describeBasicDie(1, 6, defaultNumberRolls, true) describeBasicDie(0, 6, defaultNumberRolls, true) describeBasicDie(2, 8, defaultNumberRolls, true) }) describe('compound dice', () => { describe('(1d4)d(1d6)', () => { const die = d(d(constant(1), constant(4)), d(constant(1), constant(6))) const testSpec = { variableDiceCount: { min: 1, max: 4, }, average: { average: 5.625 }, bounds: { low: 1, high: 24, expectLow: true } } testDie(die, testSpec) }) describe('(2d1)d(2d1)', () => { const die = d(d(constant(2), constant(1)), d(constant(2), constant(1))) testDie(die, basicDieTestSpecs(2, 2)) }) }) describe('exploding dice', () => { describe('6E1d6', () => { const die = explodeAbove(constant(6), d(constant(1), constant(6))) testDie(die, { diceCount: 1, average: { average: 4.2 }, variance: { variance: 10.64 }, bounds: { low: 1, expectLow: true, high: Infinity } }) }) describe('6E2d6', () => { const die = explodeAbove(constant(6), d(constant(2), constant(6))) testDie(die, { diceCount: 2, average: { average: 2 * 4.2 }, variance: { variance: 2 * 10.64 }, bounds: { low: 2, expectLow: true, high: Infinity } }) }) describe('1e1d6', () => { const die = explodeUnder(constant(1), d(constant(1), constant(6))) testDie(die, { diceCount: 1, average: { average: 4.2 }, variance: { variance: 2.24 }, bounds: { low: 2, expectLow: true, high: Infinity } }) }) }) describe('keep', () => { describe('1K2d20', () => { const die = keepHigh(constant(1), d(constant(2), constant(20))) testDie(die, { diceCount: 1, average: { average: 13.825 }, variance: { variance: 22.104 }, bounds: { low: 1, high: 20, expectLow: true, expectHigh: true } }, 800) }) describe('2K1d20', () => { const die = keepHigh(constant(2), d(constant(1), constant(20))) testDie(die, basicDieTestSpecs(1, 20)) }) describe('1k2d20', () => { const die = keepLow(constant(1), d(constant(2), constant(20))) testDie(die, { diceCount: 1, average: { average: 7.175 }, variance: { variance: 22.194 }, bounds: { low: 1, high: 20, expectLow: true, expectHigh: true } }, 800) }) describe('2k1d20', () => { const die = keepLow(constant(2), d(constant(1), constant(20))) testDie(die, basicDieTestSpecs(1, 20)) }) }) describe('again', () => { describe('10A1d10', () => { const die = againAbove(constant(10), d(constant(1), constant(10))) testDie(die, { variableDiceCount: { min: 1, max: Infinity }, average: { average: 6.11 }, variance: { variance: 19.03 }, bounds: { low: 1, high: Infinity, expectLow: true, expectHigh: false } }) }) describe('1a1d6', () => { const die = againUnder(constant(1), d(constant(1), constant(6))) testDie(die, { variableDiceCount: { min: 1, max: Infinity }, average: { average: 4.2 }, variance: { variance: 2.24 }, bounds: { low: 2, high: Infinity, expectLow: true, expectHigh: false } }) }) }) describe('threshold', () => { describe('8T3d10', () => { const die = thresholdHigh(constant(8), d(constant(3), constant(10))) testDie(die, { diceCount: 3, average: { average: 0.9 }, variance: { variance: 0.63 }, bounds: { low: 0, high: 3, expectLow: true, expectHigh: true } }) }) describe('4t3d10', () => { const die = thresholdLow(constant(4), d(constant(3), constant(10))) testDie(die, { diceCount: 3, average: { average: 1.2 }, variance: { variance: 0.72 }, bounds: { low: 0, high: 3, expectLow: true, expectHigh: true } }) }) }) describe('repeat', () => { describe('1d6 x 2', () => { const die = repeat(d(constant(1), constant(6)), constant(2)) testDie(die, { diceCount: 2, average: { average: 7 }, variance: { variance: 5.83 }, bounds: { low: 2, high: 12, expectLow: true, expectHigh: true } }) }) describe('1d6 x 1d4', () => { const die = repeat(d(constant(1), constant(6)), d(constant(1), constant(4))) testDie(die, { variableDiceCount: { min: 1, max: 4 }, average: { average: 8.75 }, bounds: { low: 1, high: 24, expectLow: true, expectHigh: false } }) }) })