# Testers {#chap-testers}

This chapter describes several testing builders which are available in the `testers` namespace.

## `hasPkgConfigModules` {#tester-hasPkgConfigModules}

<!-- Old anchor name so links still work -->
[]{#tester-hasPkgConfigModule}
Checks whether a package exposes a given list of `pkg-config` modules.
If the `moduleNames` argument is omitted, `hasPkgConfigModules` will use `meta.pkgConfigModules`.

:::{.example #ex-haspkgconfigmodules-defaultvalues}

# Check that `pkg-config` modules are exposed using default values

```nix
{
  passthru.tests.pkg-config = testers.hasPkgConfigModules {
    package = finalAttrs.finalPackage;
  };

  meta.pkgConfigModules = [ "libfoo" ];
}
```

:::

:::{.example #ex-haspkgconfigmodules-explicitmodules}

# Check that `pkg-config` modules are exposed using explicit module names

```nix
{
  passthru.tests.pkg-config = testers.hasPkgConfigModules {
    package = finalAttrs.finalPackage;
    moduleNames = [ "libfoo" ];
  };
}
```

:::

## `hasCmakeConfigModules` {#tester-hasCmakeConfigModules}

Checks whether a package exposes a given list of `*config.cmake` modules.
Note the moduleNames used in cmake find_package are case sensitive.

:::{.example #ex-hascmakeconfigmodules}

# Check that `*config.cmake` modules are exposed using explicit module names

```nix
{
  passthru.tests.cmake-config = testers.hasCmakeConfigModules {
    package = finalAttrs.finalPackage;
    moduleNames = [ "Foo" ];
  };
}
```

:::

## `lycheeLinkCheck` {#tester-lycheeLinkCheck}

Check a packaged static site's links with the [`lychee` package](https://search.nixos.org/packages?show=lychee&type=packages&query=lychee).

You may use Nix to reproducibly build static websites, such as for software documentation.
Some packages will install documentation in their `out` or `doc` outputs, or maybe you have dedicated package where you've made your static site reproducible by running a generator, such as [Hugo](https://gohugo.io/) or [mdBook](https://rust-lang.github.io/mdBook/), in a derivation.

If you have a static site that can be built with Nix, you can use `lycheeLinkCheck` to check that the hyperlinks in your site are correct, and do so as part of your Nix workflow and CI.

:::{.example #ex-lycheelinkcheck}

# Check hyperlinks in the `nix` documentation

```nix
testers.lycheeLinkCheck {
  site = nix.doc + "/share/doc/nix/manual";
}
```

:::

### Return value {#tester-lycheeLinkCheck-return}

This tester produces a package that does not produce useful outputs, but only succeeds if the hyperlinks in your site are correct. The build log will list the broken links.

It has two modes:

- Build the returned derivation; its build process will check that internal hyperlinks are correct. This runs in the sandbox, so it will not check external hyperlinks, but it is quick and reliable.

- Invoke the `.online` attribute with [`nix run`](https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-run) ([experimental](https://nixos.org/manual/nix/stable/contributing/experimental-features#xp-feature-nix-command)). This runs outside the sandbox, and checks that both internal and external hyperlinks are correct.
  Example:

  ```shell
  nix run nixpkgs#lychee.tests.ok.online
  ```

### Inputs {#tester-lycheeLinkCheck-inputs}

`site` (path or derivation) {#tester-lycheeLinkCheck-param-site}

: The path to the files to check.

`remap` (attribe set, optional) {#tester-lycheeLinkCheck-param-remap}

: An attribute set where the attribute names are regular expressions.
  The values should be strings, derivations, or path values.

  In the returned check's default configuration, external URLs are only checked when you run the `.online` attribute.

  By adding remappings, you can check offline that URLs to external resources are correct, by providing a stand-in from the file system.

  Before checking the existence of a URL, the regular expressions are matched and replaced by their corresponding values.

  Example:

  ```nix
  {
    "https://nix\\.dev/manual/nix/[a-z0-9.-]*" = "${nix.doc}/share/doc/nix/manual";