Many Nix packages are designed to run on multiple platforms. As such, it’s important to let the maintainer know which platforms your changes have been tested on. It’s not always practical to test a change on all platforms, and is not required for a pull request to be merged. Only check the systems you tested the build on in this section.

#### Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)

Packages with automated tests are much more likely to be merged in a timely fashion because it doesn’t require as much manual testing by the maintainer to verify the functionality of the package. If there are existing tests for the package, they should be run to verify your changes do not break the tests. Tests can only be run on Linux. For more details on writing and running tests, see the [section in the NixOS manual](https://nixos.org/nixos/manual/index.html#sec-nixos-tests).

#### Tested compilation of all pkgs that depend on this change using `nixpkgs-review`

If you are modifying a package, you can use `nixpkgs-review` to make sure all packages that depend on the updated package still compile correctly. The `nixpkgs-review` utility can look for and build all dependencies either based on uncommitted changes with the `wip` option or specifying a GitHub pull request number.

Review changes from pull request number 12345:

```ShellSession
nix-shell -p nixpkgs-review --run "nixpkgs-review pr 12345"
```

Alternatively, with flakes (and analogously for the other commands below):

```ShellSession
nix run nixpkgs#nixpkgs-review -- pr 12345
```

Review uncommitted changes:

```ShellSession
nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
```

Review changes from last commit:

```ShellSession
nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD"
```

#### Tested execution of all binary files (usually in `./result/bin/`)

It’s important to test any executables generated by a build when you change or create a package in nixpkgs. This can be done by looking in `./result/bin` and running any files in there, or at a minimum, the main executable for the package. For example, if you make a change to texlive, you probably would only check the binaries associated with the change you made rather than testing all of them.

#### Meets Nixpkgs contribution standards

The last checkbox is about whether it fits the guidelines in this `CONTRIBUTING.md` file. This document has detailed information on standards the Nix community has for commit messages, reviews, licensing of contributions you make to the project, etc... Everyone should read and understand the standards the community has for contributing before submitting a pull request.

### Rebasing between branches (i.e. from master to staging)

From time to time, changes between branches must be rebased, for example, if the
number of new rebuilds they would cause is too large for the target branch.

In the following example, we assume that the current branch, called `feature`,
is based on `master`, and we rebase it onto the merge base between
`master` and `staging` so that the PR can be retargeted to
`staging`. The example uses `upstream` as the remote for `NixOS/nixpkgs.git`
while `origin` is the remote you are pushing to.


```console
# Rebase your commits onto the common merge base
git rebase --onto upstream/staging... upstream/master
# Force push your changes
git push origin feature --force-with-lease
```

The syntax `upstream/staging...` is equivalent to `upstream/staging...HEAD` and
stands for the merge base between `upstream/staging` and `HEAD` (hence between
`upstream/staging` and `upstream/master`).

Then change the base branch in the GitHub PR using the *Edit* button in the upper
right corner, and switch from `master` to `staging`. *After* the PR has been
retargeted it might be necessary to do a final rebase onto the target branch, to
resolve any outstanding merge conflicts.

```console
# Rebase onto target branch
git rebase upstream/staging