Test.Sandwich.Contexts.Nix

This module contains tools for working with Nix, in order to provide Nix-built artifacts to tests.

The Nix package set (Nixpkgs) is one of the largest package sets in the world, and can be a great way to get artifacts reproducibly. All you need is a nix binary available on the PATH.

For example, the following will build a Nix environment based on Nixpkgs release 24.05, containing Emacs and Firefox.

introduceNixContext nixpkgsRelease2405 $
  introduceNixEnvironment ["emacs", "firefox"] $ do
    it "uses the environment" $ do
      envPath <- getContext nixEnvironment

      emacsVersion <- readCreateProcess (proc (envPath </> "bin" </> "emacs") ["--version"]) ""
      info [i|Emacs version: #{emacsVersion}|]

      firefoxVersion <- readCreateProcess (proc (envPath </> "bin" </> "firefox") ["--version"]) ""
      info [i|Firefox version: #{firefoxVersion}|]

Nix contexts

introduceNixContext

Arguments

:: (MonadUnliftIO m, MonadThrow m)

=> NixpkgsDerivation

Nixpkgs derivation to use

-> SpecFree (LabelValue "nixContext" NixContext :> context) m ()

Child spec

-> SpecFree context m ()

Parent spec

Introduce a NixContext, which contains information about where to find Nix and what version of Nixpkgs to use. This can be leveraged to introduce Nix packages in tests.

The NixContext contains a build cache, so if you build a given derivation more than once in your tests under this node, runs after the first one will be fast.

This function requires a nix binary to be in the PATH and will throw an exception if it isn't found.

introduceNixContext'

Arguments

:: (MonadUnliftIO m, MonadThrow m)

=> NodeOptions

Custom NodeOptions

-> NixpkgsDerivation

Nixpkgs derivation to use

-> SpecFree (LabelValue "nixContext" NixContext :> context) m ()

Child spec

-> SpecFree context m ()

Parent spec

Same as introduceNixContext, but allows passing custom NodeOptions.

introduceNixContext''

Arguments

:: (MonadUnliftIO m, MonadThrow m, HasFile context "nix")

=> NodeOptions

Custom NodeOptions

-> NixpkgsDerivation

Nixpkgs derivation to use

-> SpecFree (LabelValue "nixContext" NixContext :> context) m ()

Child spec

-> SpecFree context m ()

Parent spec

Same as introduceNixContext', but allows specifying the Nix binary via HasFile.

Nix environments

introduceNixEnvironment

Arguments

:: (HasBaseContextMonad context m, HasNixContext context, MonadUnliftIO m)

=> [Text]

List of package names to include in the Nix environment

-> SpecFree (LabelValue "nixEnvironment" FilePath :> context) m ()

-> SpecFree context m ()

Introduce a Nix environment containing the given list of packages, using the current NixContext. These packages are mashed together using the Nix symlinkJoin function. Their binaries will generally be found in "<environment path>/bin".

introduceNixEnvironment'

Arguments

:: (HasBaseContextMonad context m, HasNixContext context, MonadUnliftIO m)

=> NodeOptions

Custom NodeOptions

-> [Text]

List of package names to include in the Nix environment

-> SpecFree (LabelValue "nixEnvironment" FilePath :> context) m ()

-> SpecFree context m ()

Same as introduceNixEnvironment, but allows passing custom NodeOptions.

buildNixSymlinkJoin

Arguments

:: (HasBaseContextMonad context m, HasNixContext context, MonadUnliftIO m, MonadLogger m)

=> [Text]

Package names

-> m FilePath

Build a Nix environment, as in introduceNixEnvironment.

buildNixSymlinkJoin'

Arguments

:: (HasBaseContextMonad context m, MonadUnliftIO m, MonadLogger m)

=> NixContext

Nix context

-> [Text]

Package names

-> m FilePath

Lower-level version of buildNixSymlinkJoin.

buildNixExpression

Arguments

:: (HasBaseContextMonad context m, HasNixContext context, MonadUnliftIO m, MonadLogger m)

=> Text

Nix expression

-> m FilePath

Build a Nix environment containing the given list of packages, using the current NixContext. These packages are mashed together using the Nix "symlinkJoin" function. Their binaries will generally be found in "<environment path>/bin".

buildNixExpression'

Arguments

:: (HasBaseContextMonad context m, MonadUnliftIO m, MonadLogger m)

=> NixContext

Nix expression

-> Text

-> m FilePath

Lower-level version of buildNixExpression.

buildNixCallPackageDerivation

Arguments

:: (HasBaseContextMonad context m, HasNixContext context, MonadUnliftIO m, MonadLogger m, MonadMask m)

=> Text

Nix derivation

-> m FilePath

Build a Nix environment expressed as a derivation expecting a list of dependencies, as in the Nix "callPackage" design pattern. I.e. "{ git, gcc, stdenv, ... }: stdenv.mkDerivation {...}"

buildNixCallPackageDerivation'

Arguments

:: (HasBaseContextMonad context m, MonadUnliftIO m, MonadLogger m, MonadMask m)

=> NixContext

Nix context.

-> Text

Nix derivation.

-> m FilePath

Lower-level version of buildNixCallPackageDerivation

Nixpkgs releases

nixpkgsReleaseDefault :: NixpkgsDerivation

Currently set to nixpkgsRelease2405.

nixpkgsRelease2405 :: NixpkgsDerivation

Nixpkgs release 24.05, accessed 11/9/2024. You can compute updated values for this release (or others) by running nix-prefetch-github NixOS nixpkgs --rev release-24.05

nixpkgsRelease2311 :: NixpkgsDerivation

Nixpkgs release 23.11, accessed 2/19/2023. You can compute updated values for this release (or others) by running nix-prefetch-github NixOS nixpkgs --rev release-23.11

Types

nixContext :: Label "nixContext" NixContext

data NixContext

Constructors

NixContext

Fields

• nixContextNixBinary :: FilePath
• nixContextNixpkgsDerivation :: NixpkgsDerivation
• nixContextBuildCache :: MVar (Map Text (Async FilePath))

Instances

Show NixContext

Defined in Test.Sandwich.Contexts.Nix

Methods

showsPrec :: Int -> NixContext -> ShowS

show :: NixContext -> String

showList :: [NixContext] -> ShowS

type HasNixContext context = HasLabel context "nixContext" NixContext

nixEnvironment :: Label "nixEnvironment" FilePath

type HasNixEnvironment context = HasLabel context "nixEnvironment" FilePath

data NixpkgsDerivation

Constructors

NixpkgsDerivationFetchFromGitHub

Fields

• nixpkgsDerivationOwner :: Text
• nixpkgsDerivationRepo :: Text
• nixpkgsDerivationRev :: Text
• nixpkgsDerivationSha256 :: Text
• nixpkgsDerivationAllowUnfree :: Bool

  Set the environment variable NIXPKGS_ALLOW_UNFREE=1 when building with this derivation. Useful when you want to use packages with unfree licenses, like google-chrome.

Instances

Show NixpkgsDerivation

Defined in Test.Sandwich.Contexts.Nix

Methods

showsPrec :: Int -> NixpkgsDerivation -> ShowS

show :: NixpkgsDerivation -> String

showList :: [NixpkgsDerivation] -> ShowS

Eq NixpkgsDerivation

Defined in Test.Sandwich.Contexts.Nix

Methods

(==) :: NixpkgsDerivation -> NixpkgsDerivation -> Bool

(/=) :: NixpkgsDerivation -> NixpkgsDerivation -> Bool

defaultFileContextVisibilityThreshold :: Int