Best practice for cross-friendly bin functionality `passthru.tests` test case?

Development Nixpkgs Architecture
1

<pkg>.passthru.tests is the place for test cases for a package in the form of a derivation set, and some of them test the binary functionality of the package. In terms of dependency platforms, they are the reverse-nativeBuildInputs of this package.

For example, we may add a test case for pkgs.hello that tests the execution of

set -eu -o pipefail
HELLO_OUTPUT="$(hello)"
[[ "$HELLO_OUTPUT" == "Hello,world!" ]]

When buildPlatform == hostPlatform, it could be

{ lib
, stdenv
, runCommandLocal
, ...
}:
stdenv.mkDerivation (finalAttrs: {
  # ...
  passthru.tests.run = runCommandLocal "test-hello-run" {
    nativeBuildInputs = [ finalAttrs.finalPackage ];
  } ''
    set -eu -o pipefail
    HELLO_OUTPUT="$(hello)"
    [[ "$HELLO_OUTPUT" == "Hello,world!" ]]
  '';
})

How should it be when we consider the situation of cross compilation?

2

Don’t consider cross here. When buildPlatform != hostPlatform, regular build-time tests are also disabled.

Edit: More precisely, they’re disabled if the buildPlatform cannot execute the hostPlatform.

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3

When enabling binfmt is it running the tests?

4

Not by default. Whether one platform can execute another are inherit properties of the platform itself.

binfmt should in theory allow running any binary but it’s a giant hack. There are some extremely light usages of it in Nixpkgs for i.e. installing shell completions using the built binary but I have my reservations against even that.

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