Pure Test

Pure Test is a free, zero-dependency JavaScript test runner that spans Node.js, Deno, Bun, Cloudflare Workers, and browsers. It suits developers who want one compact tool across runtimes and are comfortable controlling test state explicitly. Its CI-friendly command line and broad runtime support are compelling, but teams needing mature APIs or automatic isolation should choose something else.

Overview

Pure Test aims to keep the test runner small while covering the essentials for unit and integration suites. Installation is a development dependency with npm install @igorjs/pure-test --save-dev. The project is Apache-2.0 licensed, and its free status removes a budget barrier for individual developers and teams.

The tradeoff is maturity. The project describes itself as beta and warns that its APIs may change, so it is better suited to projects able to absorb migration work than to organizations demanding a stable long-term test contract.

Key features

The API includes test suites, assertions, lifecycle hooks, spies, fake timers, and retry and timeout controls. That combination handles ordinary unit-test structure and timing-sensitive code without a large dependency stack. Hooks are particularly important because tests are not isolated from one another; shared state can leak between cases unless your setup and teardown code resets it.

Several familiar capabilities are intentionally outside the product's scope. There is no module mocking, snapshot testing, built-in coverage, worker isolation, or configuration-file support. A team that depends on snapshots, coverage reports, or automatic process-level separation will need supplementary tooling or a different runner.

The CLI is stronger for day-to-day and pipeline work. Multiple reporters, test filters, file watching, fail-fast execution, and sharding support make it practical for local iteration and continuous integration. The --shard option divides test files among jobs, and an empty shard exits cleanly, avoiding needless failures when a CI split leaves one worker without files.

TypeScript discovery is opt-in on Node.js through --ts; Deno and Bun discover TypeScript tests automatically. A Deno adapter registers tests as Deno.test() calls, preserving Deno's filtering and IDE-oriented workflows. Migration guides for Jest and Vitest, plus compatibility with common mock methods such as mockReturnValue and mock.calls, can reduce the effort of moving a codebase, although they do not add the unsupported mocking, snapshot, or coverage systems.

Pricing

Pure Test is free: the Apache-2.0 open-source plan costs nothing, with no paid plans, trial, renewal terms, seat charges, or usage quotas stated. That makes it suitable for personal projects, open-source maintainers, and teams that want a no-cost runner they can install and operate themselves. The price does not offset the beta status or missing features, so budget-conscious teams should still account for the engineering work needed to manage isolation, reporting, or coverage elsewhere.

Platforms

Pure Test is available on Linux, macOS, Windows, self-hosted environments, and the web. Its supported runtimes are Node.js, Deno, Bun, Cloudflare Workers, and browsers. This breadth is its clearest differentiator: a team shipping code in more than one JavaScript runtime can keep a similar runner and CLI workflow. TypeScript behavior differs by runtime, with the Node.js flag requirement contrasting with automatic discovery in Deno and Bun.

Who it's for

Choose Pure Test for a small cross-runtime project, a CI pipeline that benefits from sharding, or a team migrating from Jest or Vitest that needs a leaner runner. It is also a reasonable fit when lifecycle hooks and application-level discipline are acceptable substitutes for automatic isolation.

Look elsewhere if snapshots, built-in coverage, module mocking, worker isolation, or configuration files are core requirements. Teams with strict compatibility and stability policies should also treat the beta API warning as a material risk.

Pros and cons

Pros

• Wide runtime coverage: Node.js, Deno, Bun, Cloudflare Workers, and browsers are covered by one runner.
• Useful CI controls: Sharding, clean empty-shard exits, filtering, reporters, and fail-fast execution support real pipeline layouts.
• Lean distribution: Zero dependencies and a free Apache-2.0 license keep installation and licensing overhead low.
• Migration help: Jest and Vitest guides and common mock-method compatibility can ease adoption.

Cons

• No test isolation: Shared state can contaminate later tests, leaving cleanup to lifecycle hooks.
• Important omissions: There is no module mocking, snapshot testing, built-in coverage, worker isolation, or configuration-file support.
• Beta APIs: Changes may require maintenance as the project evolves.
• Uneven TypeScript setup: Node.js requires --ts, unlike Deno and Bun's automatic discovery.

Alternatives

Vitest is the better choice when you want a free, open-source runner with no stated plan limits and a more established Jest-oriented migration target.

Jasmine fits projects seeking a free JavaScript testing framework across Linux, macOS, web, and Windows without stated pricing or usage limits.

Mocha is a straightforward free option for projects targeting Linux or the web that prefer an open-source framework installed as a development dependency.

QUnit suits teams wanting an open-source framework distributed through CDN, npm, and Yarn, with broader listed platform coverage.

Cucumber.js is preferable when a free npm module and development-dependency installation are the desired starting point.

Web Test Runner is an alternative free open-source option focused on modern web development and browser-oriented tooling.

Testem is a free MIT-licensed open-source JavaScript test runner for Linux, macOS, and Windows.

Karma remains free across many platforms, but it is deprecated and receives no new features or general bug fixes.

Verdict

Pure Test is a strong match for developers who value one lightweight runner across several JavaScript runtimes and need practical CI sharding without license cost. Choose it when your team can enforce cleanup with hooks and live with a beta API. Choose another runner when isolation, snapshots, coverage, module mocking, or long-term API stability are non-negotiable.