'use strict';

const Sequencer = require('@jest/test-sequencer').default;

class CustomSequencer extends Sequencer {

  sort(tests) {

    if (process.env.CIRCLE_NODE_TOTAL) {

      // In CI, parallelize tests across multiple tasks.

      const nodeTotal = parseInt(process.env.CIRCLE_NODE_TOTAL, 10);

      const nodeIndex = parseInt(process.env.CIRCLE_NODE_INDEX, 10);

      tests = tests

        .sort((a, b) => (a.path < b.path ? -1 : 1))

        .filter((_, i) => i % nodeTotal === nodeIndex);

    }

    return tests;

  }

}

module.exports = CustomSequencer;