Hi! We are really excited that you are interested in contributing to Vitest. Before submitting your contribution, please make sure to take a moment and read through the following guide:
The Vitest repo is a monorepo using pnpm workspaces. The package manager used to install and link dependencies must be pnpm.
We recommend installing ni to help switching between repos using different package managers. ni
also provides the handy nr
command which running npm scripts easier:
ni
is equivalent topnpm install
nr test
is equivalent topnpm run test
To develop and test vitest
package:
-
Run
pnpm install
invitest
's root folder -
Run
pnpm run build
to build all monorepo packages
- after this, you can use
pnpm run dev
to rebuild packages as you modify code
- Run
pnpm run test
to run core testspnpm run test:ci
to run all the suitecd test/(dir) && pnpm run test
to run a specific test suite
💡 If you use VS Code, you can hit
⇧ ⌘ B
orCtrl + Shift + B
to launch all the necessary dev tasks.
If you want to use break point and explore code execution you can use the "Run and debug" feature from vscode.
-
Add a
debugger
statement where you want to stop the code execution. -
Click on the "Run and Debug" icon in the activity bar of the editor.
-
Click on the "Javascript Debug Terminal" button.
-
It will open a terminal, then type the test command:
pnpm run test
-
The execution will stop and you'll use the Debug toolbar to continue, step over, restart the process...
You may wish to test your locally-modified copy of Vitest against another package that is using it. For pnpm, after building Vitest, you can use pnpm.overrides
. Please note that pnpm.overrides
must be specified in the root package.json
and you must first list the package as a dependency in the root package.json
:
{
"dependencies": {
"vitest": "*"
},
"pnpm": {
"overrides": {
"vitest": "link:../path/to/vitest/packages/vitest"
}
}
}
And re-run pnpm install
to link the package.
Add a .npmrc
file with following line next to the package.json
:
VITE_NODE_DEPS_MODULE_DIRECTORIES=/node_modules/,/packages/
-
Checkout a topic branch from a base branch, e.g.
main
, and merge back against that branch. -
If adding a new feature:
- Add accompanying test case.
- Provide a convincing reason to add this feature. Ideally, you should open a suggestion issue first and have it approved before working on it.
-
If fixing bug:
- If you are resolving a special issue, add
(fix #xxxx[,#xxxx])
(#xxxx is the issue id) in your PR title for a better release log, e.g.fix: update entities encoding/decoding (fix #3899)
. - Provide a detailed description of the bug in the PR. Live demo preferred.
- Add appropriate test coverage if applicable.
- If you are resolving a special issue, add
-
It's OK to have multiple small commits as you work on the PR - GitHub can automatically squash them before merging.
-
Make sure tests pass!
-
Commit messages must follow the commit message convention so that changelogs can be automatically generated.
-
Use
pnpm run lint:fix
to format files according to the project guidelines.
The following section is mostly for maintainers who have commit access, but it's helpful to go through if you intend to make non-trivial contributions to the codebase.
flowchart TD
start{Followed issue\ntemplate?}
start --NO--> close1[Close and ask to\nfollow template]
start --YES--> dupe{Is duplicate?}
dupe --YES--> close2[Close and point\nto duplicate]
dupe --NO--> repro{Has proper\nreproduction?}
repro --NO--> close3[Label: 'needs reproduction'\nbot will auto close if no update\nhas been made in 3 days]
repro --YES--> real{Is actually a bug?}
real --NO--> intended{Is the intended\nbehaviour?}
intended --YES--> explain[Explain and close\npoint to docs if needed]
intended --NO--> open[Keep open for discussion\nRemove 'pending triage' label]
real --YES--> real2["1. Remove 'pending triage' label\n2. Add related feature label if\napplicable (e.g. 'feat: browser')\n3. Add priority and meta labels (see below)"]
real2 --> unusable{Does the\nbug make Vitest\nunusable?}
unusable --YES--> maj{Does the bug\naffect the majority\nof Vitest users?}
maj --YES--> p5[p5: urgent]
maj --NO--> p4[p4: important]
unusable --NO--> workarounds{Are there\nworkarounds for\nthe bug?}
workarounds --YES--> p2[p2: edge case\nhas workaround]
workarounds --NO--> p3[p3: minor bug]
flowchart TD
start{Bug fix\nor\nfeature}
start --BUG FIX--> strict_bug{"Is a 'strict fix'\ni.e. fixes an obvious\noversight with no\nside effects"}
start --FEATURE--> feature[- Discuss feature necessity\n- Is this the best way to address the need\n- Review code quality\n- Add feature labels\n- Approve if you feel strongly\nthat the feature is needed]
feature --> merge
strict_bug --YES--> strict[- Verify the fix locally\n- Review code quality\n- Require test case if applicable\n- Request changes if necessary]
strict_bug --NO--> non_strict[- Discuss the potential side\neffects of the fix, e.g.\n- Could it introduce implicit\nbehavior changes in other\ncases?\n- Does it introduce too much\nchanges?]
non_strict --> label["Add priority labels\n(see issue triaging workflow)"]
strict --> label
label --> approve
approve --> merge["Merge if approved by 2 or\nmore team members\n- Use 'Squash and Merge'\n- Edit commit message to follow\nconvention\n- In commit message body, list\nrelevant issues being fixed\ne.g. 'fix #1234, fix #1235'"]
Vitest aims to be lightweight, and this includes being aware of the number of npm dependencies and their size.
Most deps should be added to devDependencies
even if they are needed at runtime. Some exceptions are:
- Type packages. Example:
@types/*
. - Deps that cannot be properly bundled due to binary files.
- Deps that ships its own types and its type is used in vitest's own public types.
Avoid deps that has large transitive dependencies that results in bloated size compared to the functionality it provides.
If there are libraries that are needed and don't comply with our size requirements, a fork can be tried to reduce its size while we work with them to upstream our changes (see tinypool for example)
We already have many config options, and we should avoid fixing an issue by adding yet another one. Before adding an option, try to think about:
- Whether the problem is really worth addressing
- Whether the problem can be fixed with a smarter default
- Whether the problem has workaround using existing options
- Whether the problem can be addressed with a plugin instead