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Rails: 2 CPUs = 2x Testing Speed for RSpec, Test::Unit and Cucumber

Readme.md

Speedup Test::Unit + RSpec + Cucumber by running parallel on multiple CPUs (or cores).
ParallelTests splits tests into even groups(by number of tests or runtime) and runs each group in a single process with its own database.

upgrading from 0.6 ?

Setup for Rails

RailsCasts episode #413 Fast Tests still using Rails 2?

Install

If you use RSpec: ensure you have >= 2.4

As gem

# add to Gemfile
gem "parallel_tests", :group => :development

Add to config/database.yml

ParallelTests uses 1 database per test-process.

Process number 1 2 3
`ENV['TEST_ENV_NUMBER']` '' '2' '3'
test:
  database: yourproject_test<%= ENV['TEST_ENV_NUMBER'] %>

Create additional database(s)

rake parallel:create

Copy development schema (repeat after migrations)

rake parallel:prepare

Run!

rake parallel:test          # Test::Unit
rake parallel:spec          # RSpec
rake parallel:features      # Cucumber
rake parallel:features-spinach       # Spinach

rake parallel:test[1] --> force 1 CPU --> 86 seconds
rake parallel:test    --> got 2 CPUs? --> 47 seconds
rake parallel:test    --> got 4 CPUs? --> 26 seconds
...

Test by pattern (e.g. use one integration server per subfolder / see if you broke any 'user'-related tests)

rake parallel:test[^test/unit] # every test file in test/unit folder
rake parallel:test[user]  # run users_controller + user_helper + user tests
rake parallel:test['user|product']  # run user and product related tests

Example output

2 processes for 210 specs, ~ 105 specs per process
... test output ...

843 examples, 0 failures, 1 pending

Took 29.925333 seconds

Run an arbitrary task in parallel

RAILS_ENV=test parallel_test -e "rake my:custom:task"
# or
rake parallel:rake[my:custom:task]

Running things once

# effected by race-condition: first process may boot slower the second
# either sleep a bit or use a lock for example File.lock
ParallelTests.first_process? ? do_something : sleep(1)

at_exit do
  if ParallelTests.first_process?
    ParallelTests.wait_for_other_processes_to_finish
    undo_something
  end
end

Loggers

Even test group run-times

Add the RuntimeLogger to log how long each test takes to run. This log file will be loaded on the next test run, and the tests will be grouped so that each process should finish around the same time.

Rspec: Add to your .rspec_parallel (or .rspec) :

If installed as plugin: -I vendor/plugins/parallel_tests/lib
--format progress
--format ParallelTests::RSpec::RuntimeLogger --out tmp/parallel_runtime_rspec.log

Test::Unit: Add to your test_helper.rb:

require 'parallel_tests/test/runtime_logger'

RSpec: SummaryLogger

This logger logs the test output without the different processes overwriting each other.

Add the following to your .rspec_parallel (or .rspec) :

If installed as plugin: -I vendor/plugins/parallel_tests/lib
--format progress
--format ParallelTests::RSpec::SummaryLogger --out tmp/spec_summary.log

RSpec: FailuresLogger

This logger produces pasteable command-line snippets for each failed example.

E.g.

rspec /path/to/my_spec.rb:123 # should do something

Add the following to your .rspec_parallel (or .rspec) :

If installed as plugin: -I vendor/plugins/parallel_tests/lib
--format progress
--format ParallelTests::RSpec::FailuresLogger --out tmp/failing_specs.log

Cucumber: FailuresLogger

This logger logs failed cucumber scenarios to the specified file. The filename can be passed to cucumber, prefixed with '@' to rerun failures.

Usage:

cucumber --format ParallelTests::Cucumber::FailuresLogger --out tmp/cucumber_failures.log

Or add the formatter to the parallel: profile of your cucumber.yml:

parallel: --format progress --format ParallelTests::Cucumber::FailuresLogger --out tmp/cucumber_failures.log

Note if your cucumber.yml default profile uses <%= std_opts %> you may need to insert this as follows parallel: <%= std_opts %> --format progress...

To rerun failures:

cucumber @tmp/cucumber_failures.log

Setup for non-rails

gem install parallel_tests
# go to your project dir
parallel_test test/
parallel_rspec spec/
parallel_cucumber features/
parallel_spinach features/
  • use ENV['TEST_ENV_NUMBER'] inside your tests to select separate db/memcache/etc.
  • Only run selected files & folders:

    parallel_test test/bar test/baz/foo_text.rb

Options are:

-n [PROCESSES]                   How many processes to use, default: available CPUs
-p, --pattern [PATTERN]          run tests matching this pattern
    --group-by [TYPE]            group tests by:
      found - order of finding files
      steps - number of cucumber steps
      filesize - size of files on disk
      default - runtime or filesize
-m, --multiply-processes [FLOAT] use given number as a multiplier of processes to run
-s, --single [PATTERN]           Run all matching files in the same process
-i, --isolate                    Do not run any other tests in the group used by --single(-s)
-e, --exec [COMMAND]             execute this code parallel and with ENV['TEST_ENV_NUM']
-o, --test-options '[OPTIONS]'   execute test commands with those options
-t, --type [TYPE]                test(default) / rspec / cucumber / spinach
    --serialize-stdout           Serialize stdout output, nothing will be written until everything is done
    --non-parallel               execute same commands but do not in parallel, needs --exec
    --no-symlinks                Do not traverse symbolic links to find test files
    --ignore-tags [PATTERN]      When counting steps ignore scenarios with tags that match this pattern
    --nice                       execute test commands with low priority.
    --only-group [INTEGER]       Group the files, but only run the group specified here. Requires group-by filesize (will be set automatically if group-by is blank and only-group is specified)
-v, --version                    Show Version
-h, --help                       Show this.

You can run any kind of code in parallel with -e / --execute

parallel_test -n 5 -e 'ruby -e "puts %[hello from process #{ENV[:TEST_ENV_NUMBER.to_s].inspect}]"'
hello from process "2"
hello from process ""
hello from process "3"
hello from process "5"
hello from process "4"
1 Process 2 Processes 4 Processes
RSpec spec-suite 18s 14s 10s
Rails-ActionPack 88s 53s 44s

TIPS

  • [RSpec] add a .rspec_parallel to use different options, e.g. no --drb
  • [RSpec] delete script/spec
  • [Spork] does not work with parallel_tests except when using sqlite in memory
  • [RSpec] remove --loadby from you spec/*.opts
  • [RSpec] Instantly see failures (instead of just a red F) with rspec-instafail
  • [Bundler] if you have a Gemfile then bundle exec will be used to run tests
  • [Cucumber] add a parallel: foo profile to your config/cucumber.yml and it will be used to run parallel tests
  • [Cucumber] Pass in cucumber options by not giving the options an identifier ex: rake parallel:features[,,'cucumber_opts']
  • Capybara setup
  • Sphinx setup
  • Capistrano setup let your tests run on a big box instead of your laptop
  • [SQL schema format] use :ruby schema format to get faster parallel:prepare`
  • export PARALLEL_TEST_PROCESSORS=X in your environment and parallel_tests will use this number of processors by default
  • [ZSH] use quotes to use rake arguments rake "parallel:prepare[3]"
  • email_spec and/or action_mailer_cache_delivery
  • [Memcached] use different namespaces e.g. config.cache_store = ..., :namespace => "test_#{ENV['TEST_ENV_NUMBER']}"
  • zeus-parallel_tests
  • Distributed parallel test (e.g. Travis Support)

TODO

  • make tests consistently pass with --order random in .rspec
  • fix tests vs cucumber >= 1.2 unknown option --format
  • add integration tests for the rake tasks, maybe generate a rails project ...
  • add unit tests for cucumber runtime formatter
  • make windows compatible

Authors

inspired by pivotal labs

Contributors

Michael Grosser
michael@grosser.it
License: MIT
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