A Ruby script that runs tests with Pants for all projects that have been modified in the current working tree.

test_changed

#!/usr/bin/env ruby
#
# Run tests for all projects that have been modified in the Birdcage,
# relative to HEAD.
#
# For example, if you've edited files in three projects, this script will
# run tests serially for these three projects in one command.

print "Determining which files have been changed..."
$stdout.flush

birdcage_root=File.expand_path("../../", __FILE__)
test_targets = []
changed_files = `git status --porcelain`.split("\n").map do |line|
  line[3..-1]
end

# Run through all changed files, picking out their corresponding
# BUILD:tests targets.
changed_files.each do |changed_file|
  # Backtrack from the source file, hunting for the maximally-deep BUILD
  # file containing a 'tests' target.
  path_elements = changed_file.split('/')
  path_elements.each_index do |i|
    prefix = path_elements[0..(path_elements.size-1-i)]
    build_files = Dir["#{prefix.join('/')}/**/BUILD"].select do |build_file|
      found = `#{birdcage_root}/pants goal filter #{build_file}:: --filter-type=junit_tests 2> /dev/null`.split("\n")
      unless found.empty?
        test_targets += found
        break
      end
    end
  end
end

puts "  Done."

if test_targets.empty?
  puts "Working directory is clean. No tests to run."
else
  test_targets.each do |test_target|
    puts "Running tests at #{test_target}"

    # `Kernel.system` captures SIGINT for subshells only, so we set a trap to
    # explicitly exit when a user hits ^C.
    unless system("#{birdcage_root}/pants goal test #{test_target}")
      exit $?.exitstatus
    end
  end
end