task :task1 do
requires [:task2, :task3]
run { raise "error in #{id}" }
end
task :task2 do
requires [:task4]
run { log 'task2#run' }
end
task :task3 do
requires [:task4]
run { log 'task3#run' }
end
task :task4 do
run do
log 'task4#run'
sleep 1
end
end