Add --randomize --seed flag (#22987)

Outputs the seed when randomizing. Adds --seed flag to reproduce a
random order. Seeds might not produce the same order across operating
systems / bun versions.

Fixes #11847

---------

Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
This commit is contained in:
pfg
2025-09-25 23:47:46 -07:00
committed by GitHub
parent 656747bcf1
commit c4519c7552
9 changed files with 149 additions and 251 deletions

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@@ -117,6 +117,36 @@ Use the `--rerun-each` flag to run each test multiple times. This is useful for
$ bun test --rerun-each 100
```
## Randomize test execution order
Use the `--randomize` flag to run tests in a random order. This helps detect tests that depend on shared state or execution order.
```sh
$ bun test --randomize
```
When using `--randomize`, the seed used for randomization will be displayed in the test summary:
```sh
$ bun test --randomize
# ... test output ...
--seed=12345
2 pass
8 fail
Ran 10 tests across 2 files. [50.00ms]
```
### Reproducible random order with `--seed`
Use the `--seed` flag to specify a seed for the randomization. This allows you to reproduce the same test order when debugging order-dependent failures.
```sh
# Reproduce a previous randomized run
$ bun test --seed 123456
```
The `--seed` flag implies `--randomize`, so you don't need to specify both. Using the same seed value will always produce the same test execution order, making it easier to debug intermittent failures caused by test interdependencies.
## Bail out with `--bail`
Use the `--bail` flag to abort the test run early after a pre-determined number of test failures. By default Bun will run all tests and report all failures, but sometimes in CI environments it's preferable to terminate earlier to reduce CPU usage.