capability: add/use testInChild helper #604

	on: [push, pull_request]
	name: Test
	jobs:
	test:
	strategy:
	matrix:
	go-version: [1.18.x, 1.22.x, 1.23.x]
	platform: [ubuntu-20.04, ubuntu-22.04, ubuntu-24.04, windows-latest, macos-13, macos-14]
	runs-on: ${{ matrix.platform }}
	defaults:
	run:
	shell: bash
	steps:
	- name: Checkout code
	uses: actions/checkout@v4
	- name: Install Go
	uses: actions/setup-go@v5
	with:
	go-version: ${{ matrix.go-version }}
	# Disable caching as we don't have top-level go.sum needed for
	# the cache key, and specifying multiple go.sums is not trivial
	# (see https://github.com/moby/sys/pull/160 for details).
	cache: false
	- name: Set PACKAGES env
	if: ${{ matrix.go-version == '1.18.x' }}
	run: \|
	# This corresponds with the list in Makefile:1, but omits the "userns"
	# and "capability" modules, which require go1.21 as minimum.
	echo 'PACKAGES=mountinfo mount sequential signal symlink user' >> $GITHUB_ENV
	- name: go mod tidy
	run: \|
	make foreach CMD="go mod tidy"
	git diff --exit-code
	- name: go fix
	run: \|
	make foreach CMD="go fix"
	git diff --exit-code
	- name: Lint
	run: make lint
	- name: Cross build
	if: ${{ runner.os == 'Linux' }}
	run: make cross
	- name: Test
	run: \|
	uname -a
	make test

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