README.md

test-runner-benchmarks

This repo is setup to test the performance of various test runners. Specially to:

• Help the Jest team with jestjs/jest#6694.
• Help the Vitest team with vitest-dev/vitest#229 & vitest-dev/vitest#579

Results

Single-thread (on GitHub Actions CI)

Multi-thread (12 core PC)

Setup

1. Install hyperfine via these instructions:
2. Install dependencies:

yarn

Then you can run benchmarks via:

hyperfine --warmup 1 \
    'yarn workspace bun test' \
    'yarn workspace jasmine test' \
    'yarn workspace jest test' \
    'yarn workspace tape test' \
    'yarn workspace vitest test --poolOptions.threads.isolate=false'

Note

These benchmarks are supported on MacOS and Linux. Windows is not supported at this time.

Suites

• jasmine: This is our baseline, using Jasmine and happy-dom.
  • NOTE: Jasmine doesn't support shapshot testing so those tests do a basic object comparison
• bun: Same test suite, but running using Bun.
• jest: Same test suite, but running using Jest.
• tape: Same test suite, but running using Tape and ts-node.
  • NOTE: Tape doesn't support shapshot testing so those tests do a basic object comparison
• vitest: Same test suite, but running using Vitest. NOTE: That benchmarks use --poolOptions.threads.isolate=false as it has the best performance (see this comment)

Results

Benchmarks are run via GitHub Actions. You can check the latest run results here.

Philosophy

• Use hyperfine for consistent and reproducible benchmark collection
• Discard the first run (via --warmup 1) to let various caches build up
• Use minimal configurations (ie. stock configurations)
• Tests should represent a modern real-world scenario (in this case, they are copies of real files used in a real TypeScript React project)
• Tests should be updated for each test runner's best practices and APIs to give them the best chance possible to be optimized (eg. Jasmine uses APIs like createSpy() whereas Jest has jest.fn() and Vitest has vi.fn())

Other Suites

• jest-dot: It was suggested that using Jest's dot reporter might result in faster performance. In the past this benchmark repo had a jest-dot suite to validate this but after many runs, it had nearly no impact on performance. The suite has since been removed.
• jest-goloveychuk: GitHub user @goloveychuk suggested a solution which reduces Jest's memory usage. This solution was added and tested, but the performance impact was not any different.
• fastest-jest-runner: Same as jest but using fastest-jest-runner. This solution was tested for several months but its performance in this benchmark was far worse than any of the others (including the baseline jest). It was removed in 2023-02-25.
• jest-swc: Same as jest but using @swc/jest instead of ts-jest. It showed virtually no impact on performance. It was removed in 2023-05-22.