Split a big test file into multiple chunks and run them in parallel

Install
=======

```Bash
gem install parallel_split_test
```

Usage
=====

### 1: prepare your databases
To use 1 database per test-process, add this to your `config/database.yml`<br/>

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

 - `TEST_ENV_NUMBER` is '' for the first process and 2 for the 2nd, it reuses your normal test database
 - Optionally install [parallel_tests](https://github.com/grosser/parallel_tests) to get database helper tasks like `rake parallel:prepare`


### 2: find a slow/big test file

```Ruby
# spec/xxx_spec.rb
require "spec_helper"

describe "X" do
  it {sleep 5}
  it {sleep 5}
  it {sleep 5}
end
```

### 3: run
```Bash
parallel_split_test spec/xxx_spec.rb [regular test options]
```

Output
======

```Bash
parallel_split_test spec/xx_spec.rb

Running examples in 2 processes
.

Finished in 5 seconds
1 example, 0 failures
..

Finished in 1 seconds
2 examples, 0 failures

Summary:
1 example, 0 failures
2 examples, 0 failures
Took 10.06 seconds with 2 processes
```

TIPS
====
 - use `-o/--out` to get unified/clean output from all processes
 - set number of processes to use with `PARALLEL_SPLIT_TEST_PROCESSES` environment variable
 - [unify JUnit output](http://dresscode.renttherunway.com/blog/631) for rspec


before(:all) rspec hooks
========================

The `before(:all)` hooks in rspec will be executed once for every process that runs a test in an example group. This means if you have more processes than tests in a group, the `before(:all)` block for that group will be fired N times. For example, this spec has 3 tests and a `before(:all)` block:

```ruby
describe "before all behavior"
  before(:all) do
    puts "Process: #{Process.pid} Before ALL"
  end

  it "a" do
  end

  it "b" do
  end

  it "c" do
  end
end
```

When you run this with 3 or more processes you'll see the `before(:all)` call is invoked 3 times, once per each process (since "a", "b", and "c" tests are each run on a different process).

```
$ PARALLEL_SPLIT_TEST_PROCESSES=3 bundle exec parallel_split_test spec/ | grep "Before ALL"
Process: 31539 Before ALL
Process: 31538 Before ALL
Process: 31540 Before ALL
```

TODO
====
 - Cucumber support
 - Test::Unit / Minitest support

Authors
=======

### [Contributors](https://github.com/grosser/parallel_split_test/contributors)
 - [bootstraponline](https://github.com/bootstraponline)
 - [ModST](https://github.com/ModST)

[Michael Grosser](http://grosser.it)<br/>
michael@grosser.it<br/>
License: MIT<br/>
[![Build Status](https://travis-ci.org/grosser/parallel_split_test.png)](https://travis-ci.org/grosser/parallel_split_test)