pustovitDmytro / fatum

import { assert } from 'chai';

import entry from '../entry';

suite('Generators: uniform');

test('Distribution', function () {

    const min = -10;

    const max = 20;

    const segmentWidth = 1;

    const allowedMaxDiff = 0.05;

    const segments = Array.from({ length: (max - min) / segmentWidth }).map((i, index) => {

        const from = min + index * segmentWidth;

        return {

            from,

            to    : from + segmentWidth,

            count : 0

        };

    });

    for (let i = 0; i < segments.length * expectedPerSegment; i++) {

        const num = entry.uniform(min, max);

        const index = Math.ceil((num - segmentWidth) / segmentWidth) - min;

        segments[index].count += 1;

    }

    for (const segment of segments) {

        segment.error =  Math.abs(segment.count - expectedPerSegment) / expectedPerSegment;

        assert.isAtMost(

            segment.error,

            allowedMaxDiff,

            JSON.stringify(segment)

        );

    }

    const errors = segments.map(s => s.error);

    assert.isAtMost(sse(errors), allowedMaxDiff / 2, errors);

});