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https://github.com/grosser/parallel_tests

Ruby: 2 CPUs = 2x Testing Speed for RSpec, Test::Unit and Cucumber
https://github.com/grosser/parallel_tests

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

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# parallel_tests

[![Gem Version](https://badge.fury.io/rb/parallel_tests.svg)](https://rubygems.org/gems/parallel_tests)
[![Build status](https://github.com/grosser/parallel_tests/workflows/test/badge.svg)](https://github.com/grosser/parallel_tests/actions?query=workflow%3Atest&branch=master)

Speedup Minitest + RSpec + Turnip + Cucumber + Spinach by running parallel on multiple CPU cores.

ParallelTests splits tests into balanced groups (by number of lines or runtime) and runs each group in a process with its own database.

Setup for Rails
===============
[RailsCasts episode #413 Fast Tests](http://railscasts.com/episodes/413-fast-tests)

### Install
`Gemfile`:

```ruby
gem 'parallel_tests', group: [:development, :test]
```

### Add to `config/database.yml`

ParallelTests uses 1 database per test-process.

Process number123
ENV['TEST_ENV_NUMBER']'''2''3'

```yaml
test:
database: yourproject_test<%= ENV['TEST_ENV_NUMBER'] %>
```

### Create additional database(s)
rake parallel:create

### (Multi-DB) Create individual database
rake parallel:create:
rake parallel:create:secondary

### Copy development schema (repeat after migrations)
rake parallel:prepare

### Run migrations in additional database(s) (repeat after migrations)
rake parallel:migrate

### (Multi-DB) Run migrations in individual database
rake parallel:migrate:

### Setup environment from scratch (create db and loads schema, useful for CI)
rake parallel:setup

### Drop all test databases
rake parallel:drop

### (Multi-DB) Drop individual test database
rake parallel:drop:

### Run!
rake parallel:test # Minitest
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 with Regex (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
rake "parallel:spec['spec\/(?!features)']" # run RSpec tests except the tests in spec/features

### 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
```Bash
RAILS_ENV=test parallel_test -e "rake my:custom:task"
# or
rake "parallel:rake[my:custom:task]"
# limited parallelism
rake "parallel:rake[my:custom:task,2]"
```

Running setup or teardown once
===================

```Ruby
require "parallel_tests"

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

# cleanup:
# last_process? does NOT mean last finished process, just last started
ParallelTests.last_process? ? do_something : sleep(1)

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

Even test group runtimes
========================

Test groups will often run for different times, making the full test run as slow as the slowest group.

**Step 1**: Use these loggers (see below) to record test runtime

**Step 2**: The next test run will use the recorded test runtimes (use `--runtime-log ` if you picked a location different from below)

**Step 3**: Automate upload/download of test runtime from your CI system [example](https://github.com/grosser/parallel_rails_example/blob/master/.github/workflows/test.yml) (chunks need to be combined, an alternative is [amend](https://github.com/grosser/amend))

### RSpec

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

--format progress
--format ParallelTests::RSpec::RuntimeLogger --out tmp/parallel_runtime_rspec.log

To use a custom logfile location (default: `tmp/parallel_runtime_rspec.log`), use the CLI: `parallel_test spec -t rspec --runtime-log my.log`

### Minitest

Add to your `test_helper.rb`:
```ruby
require 'parallel_tests/test/runtime_logger' if ENV['RECORD_RUNTIME']
```

results will be logged to `tmp/parallel_runtime_test.log` when `RECORD_RUNTIME` is set,
so it is not always required or overwritten.

Loggers
=======

RSpec: SummaryLogger
--------------------

Log the test output without the different processes overwriting each other.

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

--format progress
--format ParallelTests::RSpec::SummaryLogger --out tmp/spec_summary.log

RSpec: FailuresLogger
-----------------------

Produce pasteable command-line snippets for each failed example. For example:

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

Add to `.rspec_parallel` or use as CLI flag:

--format progress
--format ParallelTests::RSpec::FailuresLogger --out tmp/failing_specs.log

(Not needed to retry failures, for that pass [--only-failures](https://relishapp.com/rspec/rspec-core/docs/command-line/only-failures) to rspec)

RSpec: VerboseLogger
-----------------------

Prints a single line for starting and finishing each example, to see what is currently running in each process.

```
# PID, parallel process number, spec status, example description
[14403] [2] [STARTED] Foo foo
[14402] [1] [STARTED] Bar bar
[14402] [1] [PASSED] Bar bar
```

Add to `.rspec_parallel` or use as CLI flag:

--format ParallelTests::RSpec::VerboseLogger

Cucumber: FailuresLogger
-----------------------

Log 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
parallel_rspec
parallel_cucumber
parallel_spinach

- use `ENV['TEST_ENV_NUMBER']` inside your tests to select separate db/memcache/etc. (docker compose: expose it)

- Only run a subset of files / folders:

`parallel_test test/bar test/baz/foo_text.rb`

- Pass test-options and files via `--`:

`parallel_rspec -- -t acceptance -f progress -- spec/foo_spec.rb spec/acceptance`

- Pass in test options, by using the -o flag (wrap everything in quotes):

`parallel_cucumber -n 2 -o '-p foo_profile --tags @only_this_tag or @only_that_tag --format summary'`

Options are:

-n [PROCESSES] How many processes to use, default: available CPUs
-p, --pattern [PATTERN] run tests matching this regex pattern
--exclude-pattern [PATTERN] exclude tests matching this regex pattern
--group-by [TYPE] group tests by:
found - order of finding files
steps - number of cucumber/spinach steps
scenarios - individual cucumber scenarios
filesize - by size of the file
runtime - info from runtime log
default - runtime when runtime log is filled otherwise 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)
--isolate-n [PROCESSES] Use 'isolate' singles with number of processes, default: 1
--highest-exit-status Exit with the highest exit status provided by test run(s)
--failure-exit-code [INT] Specify the exit code to use when tests fail
--specify-groups [SPECS] Use 'specify-groups' if you want to specify multiple specs running in multiple
processes in a specific formation. Commas indicate specs in the same process,
pipes indicate specs in a new process. Cannot use with --single, --isolate, or
--isolate-n. Ex.
$ parallel_tests -n 3 . --specify-groups '1_spec.rb,2_spec.rb|3_spec.rb'
Process 1 will contain 1_spec.rb and 2_spec.rb
Process 2 will contain 3_spec.rb
Process 3 will contain all other specs
--only-group INT[,INT] Only run the given group numbers.
Changes `--group-by` default to 'filesize'.
-e, --exec [COMMAND] execute this code parallel and with ENV['TEST_ENV_NUMBER']
-o, --test-options '[OPTIONS]' execute test commands with those options
-t, --type [TYPE] test(default) / rspec / cucumber / spinach
--suffix [PATTERN] override built in test file pattern (should match suffix):
'_spec.rb$' - matches rspec files
'_(test|spec).rb$' - matches test or spec files
--serialize-stdout Serialize stdout output, nothing will be written until everything is done
--prefix-output-with-test-env-number
Prefixes test env number to the output when not using --serialize-stdout
--combine-stderr Combine stderr into stdout, useful in conjunction with --serialize-stdout
--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.
--runtime-log [PATH] Location of previously recorded test runtimes
--allowed-missing [INT] Allowed percentage of missing runtimes (default = 50)
--allow-duplicates When detecting files to run, allow duplicates
--unknown-runtime [FLOAT] Use given number as unknown runtime (otherwise use average time)
--first-is-1 Use "1" as TEST_ENV_NUMBER to not reuse the default test environment
--fail-fast Stop all groups when one group fails (best used with --test-options '--fail-fast' if supported
--verbose Print debug output
--verbose-command Combines options --verbose-process-command and --verbose-rerun-command
--verbose-process-command Print the command that will be executed by each process before it begins
--verbose-rerun-command After a process fails, print the command executed by that process
--quiet Print only tests output
-v, --version Show Version
-h, --help Show this.

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

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 Process2 Processes4 Processes
RSpec spec-suite18s14s10s
Rails-ActionPack88s53s44s

TIPS
====

### RSpec

- Add a `.rspec_parallel` to use different options, e.g. **no --drb**
- Remove `--loadby` from `.rspec`
- Instantly see failures (instead of just a red F) with [rspec-instafail](https://github.com/grosser/rspec-instafail)
- Use [rspec-retry](https://github.com/NoRedInk/rspec-retry) (not rspec-rerun) to rerun failed tests.
- [JUnit formatter configuration](https://github.com/grosser/parallel_tests/wiki#with-rspec_junit_formatter----by-jgarber)
- Use [parallel_split_test](https://github.com/grosser/parallel_split_test) to run multiple scenarios in a single spec file, concurrently. (`parallel_tests` [works at the file-level and intends to stay that way](https://github.com/grosser/parallel_tests/issues/747#issuecomment-580216980))

### Cucumber

- Add a `parallel: foo` profile to your `config/cucumber.yml` and it will be used to run parallel tests
- [ReportBuilder](https://github.com/rajatthareja/ReportBuilder) can help with combining parallel test results
- Supports Cucumber 2.0+ and is actively maintained
- Combines many JSON files into a single file
- Builds a HTML report from JSON with support for debug msgs & embedded Base64 images.

### General
- [ZSH] use quotes to use rake arguments `rake "parallel:prepare[3]"`
- [Memcached] use different namespaces

e.g. `config.cache_store = ..., namespace: "test_#{ENV['TEST_ENV_NUMBER']}"`
- Debug errors that only happen with multiple files using `--verbose` and [cleanser](https://github.com/grosser/cleanser)
- `export PARALLEL_TEST_PROCESSORS=13` to override default processor count
- Shell alias: `alias prspec='parallel_rspec -m 2 --'`
- [Spring] Add the [spring-commands-parallel-tests](https://github.com/DocSpring/spring-commands-parallel-tests) gem to your `Gemfile` to get `parallel_tests` working with Spring.
- `--first-is-1` will make the first environment be `1`, so you can test while running your full suite.

`export PARALLEL_TEST_FIRST_IS_1=true` will provide the same result
- [email_spec and/or action_mailer_cache_delivery](https://github.com/grosser/parallel_tests/wiki)
- [zeus-parallel_tests](https://github.com/sevos/zeus-parallel_tests)
- [Distributed Parallel Tests on CI systems)](https://github.com/grosser/parallel_tests/wiki/Distributed-Parallel-Tests-on-CI-systems) learn how `parallel_tests` can run on distributed servers such as Travis and GitLab-CI. Also shows you how to use parallel_tests without adding `TEST_ENV_NUMBER`-backends
- [Capybara setup](https://github.com/grosser/parallel_tests/wiki)
- [Sphinx setup](https://github.com/grosser/parallel_tests/wiki)
- [Capistrano setup](https://github.com/grosser/parallel_tests/wiki/Remotely-with-capistrano) let your tests run on a big box instead of your laptop

Contribute your own gotchas to the [Wiki](https://github.com/grosser/parallel_tests/wiki) or even better open a PR :)

Authors
====
inspired by [pivotal labs](https://blog.pivotal.io/labs/labs/parallelize-your-rspec-suite)

### [Contributors](https://github.com/grosser/parallel_tests/contributors)
- [Charles Finkel](http://charlesfinkel.com/)
- [Indrek Juhkam](http://urgas.eu)
- [Jason Morrison](http://jayunit.net)
- [jinzhu](http://github.com/jinzhu)
- [Joakim Kolsjö](http://www.rubyblocks.se)
- [Kevin Scaldeferri](http://kevin.scaldeferri.com/blog/)
- [Kpumuk](http://kpumuk.info/)
- [Maksim Horbul](http://github.com/mhorbul)
- [Pivotal Labs](http://www.pivotallabs.com)
- [Rohan Deshpande](http://github.com/rdeshpande)
- [Tchandy](http://thiagopradi.net/)
- [Terence Lee](http://hone.heroku.com/)
- [Will Bryant](http://willbryant.net/)
- [Fred Wu](http://fredwu.me)
- [xxx](https://github.com/xxx)
- [Levent Ali](http://purebreeze.com/)
- [Michael Kintzer](https://github.com/rockrep)
- [nathansobo](https://github.com/nathansobo)
- [Joe Yates](http://titusd.co.uk)
- [asmega](http://www.ph-lee.com)
- [Doug Barth](https://github.com/dougbarth)
- [Geoffrey Hichborn](https://github.com/phene)
- [Trae Robrock](https://github.com/trobrock)
- [Lawrence Wang](https://github.com/levity)
- [Sean Walbran](https://github.com/seanwalbran)
- [Lawrence Wang](https://github.com/levity)
- [Potapov Sergey](https://github.com/greyblake)
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- [Pedro Carriço](https://github.com/pedrocarrico)
- [Pablo Manrubia Díez](https://github.com/pmanrubia)
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- [Georg Friedrich](https://github.com/georg)
- [R. Tyler Croy](https://github.com/rtyler)
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- [Ari Pollak](https://github.com/aripollak)
- [Aaron Jensen](https://github.com/aaronjensen)
- [Artur Roszczyk](https://github.com/sevos)
- [Caleb Tomlinson](https://github.com/calebTomlinson)
- [Jawwad Ahmad](https://github.com/jawwad)
- [Iain Beeston](https://github.com/iainbeeston)
- [Alejandro Pulver](https://github.com/alepulver)
- [Felix Clack](https://github.com/felixclack)
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- [Micah Geisel](https://github.com/botandrose)
- [Exoth](https://github.com/Exoth)
- [sidfarkus](https://github.com/sidfarkus)
- [Colin Harris](https://github.com/aberant)
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- [Stanislaw Wozniak](https://github.com/sponte)
- [Dmitry Polushkin](https://github.com/dmitry)
- [Samer Masry](https://github.com/smasry)
- [Volodymyr Mykhailyk](https:/github.com/volodymyr-mykhailyk)
- [Mike Mueller](https://github.com/mmueller)
- [Aaron Jensen](https://github.com/aaronjensen)
- [Ed Slocomb](https://github.com/edslocomb)
- [Cezary Baginski](https://github.com/e2)
- [Marius Ioana](https://github.com/mariusioana)
- [Lukas Oberhuber](https://github.com/lukaso)
- [Ryan Zhang](https://github.com/ryanus)
- [Rhett Sutphin](https://github.com/rsutphin)
- [Doc Ritezel](https://github.com/ohrite)
- [Alexandre Wilhelm](https://github.com/dogild)
- [Jerry](https://github.com/boblington)
- [Aleksei Gusev](https://github.com/hron)
- [Scott Olsen](https://github.com/scottolsen)
- [Andrei Botalov](https://github.com/abotalov)
- [Zachary Attas](https://github.com/snackattas)
- [David Rodríguez](https://github.com/deivid-rodriguez)
- [Justin Doody](https://github.com/justindoody)
- [Sandeep Singh](https://github.com/sandeepnagra)
- [Calaway](https://github.com/calaway)
- [alboyadjian](https://github.com/alboyadjian)
- [Nathan Broadbent](https://github.com/ndbroadbent)
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- [Josh Westbrook](https://github.com/joshwestbrook)
- [Jay Dorsey](https://github.com/jaydorsey)
- [hatsu](https://github.com/hatsu38)

[Michael Grosser](http://grosser.it)

[email protected]

License: MIT