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We have two groups of test suites: one for Rust, and one for Node.js.


  • just test for running all tests.
  • just test-rust for running all Rust tests.
  • just test-node for running all Node.js tests.
  • just test-node rolldown for running only Rolldown's Node.js tests.
  • just test-node rollup for running only Rollup's tests.

Rust Tests

Rust tests cases are stored in

  • /crates/rolldown/tests/esbuild
  • /crates/rolldown/tests/fixtures

How test cases are defined

A test case is a folder that contains _config.json.

_config.json contains the configuration for the test suite. If everything works right, you should be able to have auto-completion while editing _config.json due to the config.

For all available options, you could refer to

Rolldown will bundle the input into /dist, and using the same node instance to execute every entry file in /dist orderly. If _test.mjs is found in test case folder, it will be executed after all entry points are executed.

Snapshot testing

Rolldown uses insta for rust snapshot testing. You could use

  • cargo insta review to review the new snapshot one by one.
  • cargo insta accept to accept all new snapshots at once.

Node.js Tests


Make sure to build Node.js bindings before running these tests.

Node.js API tests

Tests located in packages/rolldown/tests are used to test Rolldown's Node.js API (i.e. the API of the rolldown package published on NPM).

It is our goal to align Rolldown's Node.js API with that of Rollup's as much as possible, and the tests are used to verify API alignment and track the progress. Currently, there are many Rollup options that are not yet supported. If you implemented support for additional options from rollup, please add corresponding test cases for them.

  • just test-node rolldown will run rolldown tests.
  • just test-node rolldown --update will run tests and update snapshots.

Run tests of the specific file

To run tests of the specific file, you could use

just test-node rolldown test-file-name

For example, to run tests in fixture.test.ts, you could use just test-node rolldown fixture.

Run the specific test

To run specific test, you could use

just test-node rolldown -t test-name

Names of tests in fixture.test.ts are defined with their folder names. tests/fixtures/resolve/alias will has test name resolve/alias.

To run the tests/fixtures/resolve/alias test, you could use just test-node rolldown -t resolve/alias.


  • just test-node rolldown -t aaa bbb is different from just test-node rolldown -t "aaa bbb". The former will run tests that either contains aaa or bbb, while the latter will run tests, whose name contain aaa bbb.

  • For more advanced usage, please refer to

Rollup behavior alignment tests

We also aim for behavior alignment with Rollup by running Rollup's own tests against Rolldown.

To achieve this, each test case in packages/rollup-tests/test proxies to the corresponding test in the rollup git submodule in project root.

The git submodule should have been initialized after running just init when setting up the project, but you should also run just update to update the submodule before running the Rollup tests.

In /packages/rollup-tests:

  • just test-node rollup will run rollup tests.
  • just test-node rollup --update will run and update the tests' status.

Released under the MIT License.