Access downloaded files in a formula's test block

Question

I'm creating a Homebrew formula for a C library that includes its own test suite. As part of the test block for the formula, I'd like to run the tests that are included with the downloaded files. The tests run as a make target (make test). However, Homebrew test blocks run in their own temporary directory and the downloaded files are not in the path. That is, the following doesn't work because it can't find the files:

test do
  system "make", "test"
end

How can I access the location into which the files were originally downloaded and unpacked? I haven't been able to find any information about that in the docs. Or is there a better solution for Homebrew tests in this case?

Answer 1

The test do block is meant to test if a formula has correctly been installed, not to run test suits. If the tests don’t take too long you can run them as part of the install:

def install
  # ...
  system "make", "test"
  # ...
end

To answer your question there’s no reliable way to get the original unpacked directory because it’s destroyed after install and the user may have deleted the cached tarball (with e.g. brew cleanup) so you’d have to re-download it.

A solution is to copy the necessary test files somewhere during the install step then use them directly or copy them in the current directory when testing, e.g.:

def install
  # ...
  libexec.install "tests"
end

test do
  cp_r (libexec/"tests"), "."
  cd "tests" do
    # I’m assuming the Makefile's paths can be given
    # as variables here.
    system "make", "test", "LIB=#{lib}", "INCLUDE=#{include}"
  end
end