@jest/test-sequencer

method allFailedTests

allFailedTests: (tests: Array<Test>) => Array<Test> | Promise<Array<Test>>;

method cacheResults

cacheResults: (tests: Array<Test>, results: AggregatedResult) => void;

method shard

shard: (
    tests: Array<Test>,
    options: ShardOptions
) => Array<Test> | Promise<Array<Test>>;

• Select tests for shard requested via --shard=shardIndex/shardCount Sharding is applied before sorting

  Parameter tests

  All tests

  Parameter options

  shardIndex and shardIndex to select

  Example 1

  class CustomSequencer extends Sequencer {
   shard(tests, { shardIndex, shardCount }) {
     const shardSize = Math.ceil(tests.length / options.shardCount);
     const shardStart = shardSize * (options.shardIndex - 1);
     const shardEnd = shardSize * options.shardIndex;
     return [...tests]
      .sort((a, b) => (a.path > b.path ? 1 : -1))
      .slice(shardStart, shardEnd);
   }
  }

method sort

sort: (tests: Array<Test>) => Array<Test> | Promise<Array<Test>>;

• Sort test to determine order of execution Sorting is applied after sharding

  Parameter tests

  class CustomSequencer extends Sequencer {
    sort(tests) {
      const copyTests = Array.from(tests);
      return [...tests].sort((a, b) => (a.path > b.path ? 1 : -1));
    }
  }