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import * as fc from 'fast-check';
import {
addArrayIntToNew,
addOneToPositiveArrayInt,
ArrayInt,
ArrayInt64,
fromNumberToArrayInt64,
substractArrayInt64,
substractArrayIntToNew,
trimArrayIntInplace,
} from '../../../../src/distribution/internals/ArrayInt';
describe('ArrayInt', () => {
describe('addArrayIntToNew', () => {
// Skip next tests if BigInt is not supported
if (typeof BigInt === 'undefined') return it('no test', () => expect(true).toBe(true));
it('Should properly compute a plus b', () =>
fc.assert(
fc.property(arrayIntArb(), arrayIntArb(), (a, b) => {
const r = addArrayIntToNew(a, b);
expect(arrayIntToBigInt(r)).toEqual(arrayIntToBigInt(a) + arrayIntToBigInt(b));
})
));
});
describe('addOneToPositiveArrayInt', () => {
// Skip next tests if BigInt is not supported
if (typeof BigInt === 'undefined') return it('no test', () => expect(true).toBe(true));
it('Should properly compute a plus 1', () =>
fc.assert(
fc.property(arrayIntArb(), (a) => {
fc.pre(a.sign === 1);
const r = { sign: a.sign, data: a.data.slice(0) };
addOneToPositiveArrayInt(r);
expect(arrayIntToBigInt(r)).toEqual(arrayIntToBigInt(a) + BigInt(1));
})
));
});
describe('substractArrayIntToNew', () => {
// Skip next tests if BigInt is not supported
if (typeof BigInt === 'undefined') return it('no test', () => expect(true).toBe(true));
it('Should properly compute a minus b', () =>
fc.assert(
fc.property(arrayIntArb(), arrayIntArb(), (a, b) => {
const r = substractArrayIntToNew(a, b);
expect(arrayIntToBigInt(r)).toEqual(arrayIntToBigInt(a) - arrayIntToBigInt(b));
})
));
});
describe('trimArrayIntInplace', () => {
it.each`
zero
${{ sign: 1, data: [] }}
${{ sign: 1, data: [0] }}
${{ sign: 1, data: [0, 0, 0, 0, 0] }}
${{ sign: -1, data: [] }}
${{ sign: -1, data: [0] }}
${{ sign: -1, data: [0, 0, 0, 0, 0] }}
`('Should build a unique representation for zero (including $zero}', ({ zero }) =>
expect(trimArrayIntInplace(zero)).toEqual({ sign: 1, data: [0] })
);
// Skip next tests if BigInt is not supported
if (typeof BigInt === 'undefined') return it('no test', () => expect(true).toBe(true));
it('Should trim leading zeros but preserve the value', () =>
fc.assert(
fc.property(arrayIntArb(), (a) => {
const originalValue = arrayIntToBigInt(a);
const r = trimArrayIntInplace(a);
expect(r).toBe(a);
expect(r.data).not.toHaveLength(0);
if (r.data.length !== 1) {
expect(r.data[0]).not.toBe(0);
}
expect(arrayIntToBigInt(r)).toEqual(originalValue);
})
));
});
describe('fromNumberToArrayInt64', () => {
it('Should be able to convert any 32 bits positive integer to an ArrayInt64', () =>
fc.assert(
fc.property(fc.integer({ min: 0, max: 0xffffffff }), (value) => {
const arrayInt = fromNumberToArrayInt64(arrayInt64Buffer(), value);
expect(arrayInt).toEqual({ sign: 1, data: [0, value] });
})
));
it('Should be able to convert any 32 bits negative integer to an ArrayInt64', () =>
fc.assert(
fc.property(fc.integer({ min: 1, max: 0xffffffff }), (value) => {
const arrayInt = fromNumberToArrayInt64(arrayInt64Buffer(), -value);
expect(arrayInt).toEqual({ sign: -1, data: [0, value] });
})
));
it('Should be able to convert any safe integer to an ArrayInt64', () =>
fc.assert(
fc.property(fc.maxSafeInteger(), (value) => {
const arrayInt = fromNumberToArrayInt64(arrayInt64Buffer(), value);
expect(arrayInt.sign).toBe(value < 0 ? -1 : 1);
expect(arrayInt.data).toHaveLength(2);
const arrayIntHexaRepr =
// @ts-ignore
arrayInt.data[0].toString(16).padStart(8, '0') + arrayInt.data[1].toString(16).padStart(8, '0');
// @ts-ignore
const valueHexaRepr = Math.abs(value).toString(16).padStart(16, '0');
expect(arrayIntHexaRepr).toBe(valueHexaRepr);
})
));
it('Should be able to read back itself using toNumber', () =>
fc.assert(
fc.property(fc.maxSafeInteger(), (value) => {
const arrayInt = fromNumberToArrayInt64(arrayInt64Buffer(), value);
expect(toNumber(arrayInt)).toBe(value);
})
));
});
describe('substractArrayInt64', () => {
// Skip next tests if BigInt is not supported
if (typeof BigInt === 'undefined') return it('no test', () => expect(true).toBe(true));
const fromBigIntToArrayInt64 = (n: bigint): ArrayInt64 => {
const posN = n < BigInt(0) ? -n : n;
return {
sign: n < BigInt(0) ? -1 : 1,
data: [Number(posN >> BigInt(32)), Number(posN % (BigInt(1) << BigInt(32)))],
};
};
it('Should be able to substract two non-overflowing ArrayInt64', () =>
fc.assert(
fc.property(fc.bigIntN(64), fc.bigIntN(64), (a, b) => {
const min = a < b ? a : b;
const max = a < b ? b : a;
const result = max - min;
fc.pre(result < BigInt(1) << BigInt(64));
const minArrayInt = fromBigIntToArrayInt64(min);
const maxArrayInt = fromBigIntToArrayInt64(max);
const resultArrayInt = fromBigIntToArrayInt64(result);
expect(substractArrayInt64(arrayInt64Buffer(), maxArrayInt, minArrayInt)).toEqual(resultArrayInt);
})
));
});
});
// Helpers
const arrayIntArb = () =>
fc.record({
sign: fc.constantFrom(1 as const, -1 as const),
data: fc.array(fc.integer({ min: 0, max: 0xffffffff })),
});
function arrayIntToBigInt(arrayInt: ArrayInt): bigint {
let current = BigInt(0);
for (let index = 0; index < arrayInt.data.length; ++index) {
current <<= BigInt(32);
current += BigInt(arrayInt.data[index]);
}
return current * BigInt(arrayInt.sign);
}
function arrayInt64Buffer(): ArrayInt64 {
return { sign: 1, data: [0, 0] };
}
function toNumber(arrayInt: ArrayInt): number {
let current = arrayInt.data[0];
const arrayIntLength = arrayInt.data.length;
for (let index = 1; index < arrayIntLength; ++index) {
current *= 0x100000000;
current += arrayInt.data[index];
}
return current * (arrayInt.sign || 1);
}
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