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import * as fc from 'fast-check';
import { mocked } from '../../../__test-helpers__/mocked';
import { unsafeUniformArrayIntDistributionInternal } from '../../../../src/distribution/internals/UnsafeUniformArrayIntDistributionInternal';
import { ArrayInt } from '../../../../src/distribution/internals/ArrayInt';
import { RandomGenerator } from '../../../../src/generator/RandomGenerator';
import * as UnsafeUniformIntDistributionInternalMock from '../../../../src/distribution/internals/UnsafeUniformIntDistributionInternal';
jest.mock('../../../../src/distribution/internals/UnsafeUniformIntDistributionInternal');
function buildUniqueRng(clonedRng?: RandomGenerator) {
if (clonedRng !== undefined) {
return {
clone() {
return clonedRng;
},
} as RandomGenerator;
}
return {} as RandomGenerator;
}
function clean() {
jest.resetAllMocks();
jest.clearAllMocks();
}
beforeEach(clean);
describe('unsafeUniformArrayIntDistributionInternal', () => {
it.each`
rangeSize | resultingArrayInt | description
${[10, 20, 30]} | ${[1, 1, 1]} | ${'all generated values are smaller'}
${[10, 20, 30]} | ${[8, 520, 1000]} | ${'some generated values are greater but resulting array is smaller'}
${[10, 20, 30]} | ${[10, 20, 29]} | ${'resulting array is rangeSize minus one'}
${[1]} | ${[0]} | ${'smallest possible rangeSize'}
${[0, 0, 1, 0, 1, 0]} | ${[0, 0, 1, 0, 0, 1]} | ${'rangeSize starting by and including zeros'}
`('Should only call the rangeSize.length times when $description', ({ rangeSize, resultingArrayInt }) => {
// Arrange
const { unsafeUniformIntDistributionInternal } = mocked(UnsafeUniformIntDistributionInternalMock);
const initialRng = buildUniqueRng();
for (let idx = 0; idx !== resultingArrayInt.length; ++idx) {
// In terms of calls, the expectedRangeSize is:
// [ rangeSize[0] + 1 , 0x1_00000000 , ... ]
// In other words, we can generate (with the same probability) any number in:
// [ between 0 (inc) and rangeSize[0] (inc) , between 0 (inc) and 0xffffffff (inc) , ... ]
// Values outside greater or equal to rangeSize will be rejected. We will retry until we get a valid value.
const expectedRangeSize = idx === 0 ? rangeSize[0] + 1 : 0x100000000;
const generatedItem = resultingArrayInt[idx];
unsafeUniformIntDistributionInternal.mockImplementationOnce((askedRangeSize, rng) => {
expect(askedRangeSize).toBe(expectedRangeSize);
expect(rng).toBe(initialRng);
return generatedItem;
});
}
// Act
const g = unsafeUniformArrayIntDistributionInternal(arrayIntBuffer(rangeSize.length).data, rangeSize, initialRng);
// Assert
expect(g).toEqual(resultingArrayInt);
expect(unsafeUniformIntDistributionInternal).toHaveBeenCalledTimes(resultingArrayInt.length);
});
it.each`
rangeSize | rejections | resultingArrayInt | description
${[10, 20, 30]} | ${[10, 20, 30]} | ${[1, 1, 1]} | ${'first generated value is the rangeSize itself'}
${[10, 20, 30]} | ${[10, 50, 0]} | ${[1, 1, 1]} | ${'first generated value is greater than the rangeSize due to middle item'}
${[10, 20, 30]} | ${[10, 20, 50]} | ${[1, 1, 1]} | ${'first generated value is greater than the rangeSize due to last item'}
${[10, 20, 30]} | ${[10, 100, 1000, 10, 100, 1000, 10, 100, 1000]} | ${[1, 1, 1]} | ${'multiple rejections in a row'}
`('Should retry until we get a valid value when $description', ({ rangeSize, rejections, resultingArrayInt }) => {
// Arrange
const { unsafeUniformIntDistributionInternal } = mocked(UnsafeUniformIntDistributionInternalMock);
const initialRng = buildUniqueRng();
for (let idx = 0; idx !== rejections.length; ++idx) {
// Rq: We check on `idx % rangeSize.length === 0` as our surrent implementation does not quit earlier.
// It will generate a full value before rejecting it.
const expectedRangeSize = idx % rangeSize.length === 0 ? rangeSize[0] + 1 : 0x100000000;
const generatedItem = rejections[idx];
unsafeUniformIntDistributionInternal.mockImplementationOnce((askedRangeSize, rng) => {
expect(askedRangeSize).toBe(expectedRangeSize);
expect(rng).toBe(initialRng);
return generatedItem;
});
}
for (let idx = 0; idx !== resultingArrayInt.length; ++idx) {
const expectedRangeSize = idx === 0 ? rangeSize[0] + 1 : 0x100000000;
const generatedItem = resultingArrayInt[idx];
unsafeUniformIntDistributionInternal.mockImplementationOnce((askedRangeSize, rng) => {
expect(askedRangeSize).toBe(expectedRangeSize);
expect(rng).toBe(initialRng);
return generatedItem;
});
}
// Act
const g = unsafeUniformArrayIntDistributionInternal(arrayIntBuffer(rangeSize.length).data, rangeSize, initialRng);
// Assert
expect(g).toEqual(resultingArrayInt);
expect(unsafeUniformIntDistributionInternal).toHaveBeenCalledTimes(rejections.length + resultingArrayInt.length);
});
it('Should call unsafeUniformIntDistributionInternal until it produces a valid ArrayInt', () =>
// Identical to the test above "Should retry until we get a valid value when $description" but with property based testing
fc.assert(
fc
.property(
fc
.bigInt({ min: BigInt(1) })
.chain((rangeSize) =>
fc.record(
{
rangeSize: fc.constant(rangeSize),
rejectedValues: fc.array(fc.bigInt({ min: rangeSize })),
validValue: fc.bigInt({ min: BigInt(0), max: rangeSize - BigInt(1) }),
},
{ withDeletedKeys: false }
)
)
.map(({ rangeSize, rejectedValues, validValue }) => {
let rangeSizeArrayIntData = fromBigUintToArrayIntData(rangeSize);
let validValueArrayIntData = fromBigUintToArrayIntData(validValue);
let rejectedValuesArrayIntData = rejectedValues.map(fromBigUintToArrayIntData);
const maxDataLength = [
rangeSizeArrayIntData,
validValueArrayIntData,
...rejectedValuesArrayIntData,
].reduce((acc, data) => Math.max(acc, data.length), 0);
rangeSizeArrayIntData = padDataOfArrayInt(rangeSizeArrayIntData, maxDataLength);
validValueArrayIntData = padDataOfArrayInt(validValueArrayIntData, maxDataLength);
rejectedValuesArrayIntData = rejectedValuesArrayIntData.map((v) => padDataOfArrayInt(v, maxDataLength));
return {
rangeSize: rangeSizeArrayIntData,
rejectedValues: rejectedValuesArrayIntData,
validValue: validValueArrayIntData,
};
}),
fc.context(),
({ rangeSize, rejectedValues, validValue }, ctx) => {
// Arrange
const initialRng = buildUniqueRng();
for (const rejected of rejectedValues) {
// Our mock for unsafeUniformIntDistributionInternal starts by producing invalid values
// (too large for the requested range).
// All those values should be rejected by unsafeUniformArrayIntDistributionInternal.
// Internally unsafeUniformArrayIntDistributionInternal do not optimize calls (for the moment)
// it always queries for all the data then checks if the data is ok or not given rangeSize.
// In other words, if rangeSize = [1,1,1], the algorithm will query for at least three entries
// even if it can stop earlier [1,2,1,...] (when receiving the 2, we know it will not fit our needs).
mockResponse(rejected, initialRng, ctx);
}
mockResponse(validValue, initialRng, ctx);
mockRejectNextCalls(ctx);
// Act
const g = unsafeUniformArrayIntDistributionInternal(
arrayIntBuffer(rangeSize.length).data,
rangeSize,
initialRng
);
// Assert
expect(g).toEqual(validValue);
}
)
.beforeEach(clean)
));
});
// Helpers
function arrayIntBuffer(size: number): ArrayInt {
return { sign: 1, data: Array(size).fill(0) };
}
function fromBigUintToArrayIntData(n: bigint): ArrayInt['data'] {
const data: number[] = [];
const repr = n.toString(16);
for (let sectionEnd = repr.length; sectionEnd > 0; sectionEnd -= 8) {
data.push(parseInt(repr.substring(sectionEnd - 8, sectionEnd), 16));
}
return data.reverse();
}
function padDataOfArrayInt(arrayIntData: ArrayInt['data'], length: number): ArrayInt['data'] {
return [...Array(length - arrayIntData.length).fill(0), ...arrayIntData];
}
function mockResponse(arrayIntData: ArrayInt['data'], clonedRng: RandomGenerator, ctx: fc.ContextValue) {
const { unsafeUniformIntDistributionInternal } = mocked(UnsafeUniformIntDistributionInternalMock);
for (const item of arrayIntData) {
unsafeUniformIntDistributionInternal.mockImplementationOnce((rangeSize, rng) => {
expect(rng).toBe(clonedRng);
ctx.log(`unsafeUniformIntDistributionInternal(${rangeSize}) -> ${item}`);
return item;
});
}
}
function mockRejectNextCalls(ctx: fc.ContextValue) {
const { unsafeUniformIntDistributionInternal } = mocked(UnsafeUniformIntDistributionInternalMock);
unsafeUniformIntDistributionInternal.mockImplementationOnce((rangeSize, _rng) => {
ctx.log(`unsafeUniformIntDistributionInternal(${rangeSize}) -> [..., <rng>]`);
throw new Error('No more calls expected');
});
}
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