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1. First step of the test-unit

Let's getting start test-unit.

This document creates an example gem package called sample with the test-unit testing framework.

2. Install bundler and test-unit.

gem install bundler
gem install test-unit

The gem list command output installed packages. You will find the following lines.

gem list
...
bundler (1.14.6)
...
test-unit (3.2.3)

3. Create gem template.

Next, create a gem template using bundler command. This command generates package skeleton with a testing framework. However, this command can't generate test templates for test-unit.

So, First create gem template with the minitest testing framework. (It's similar to unit-test). After that, replace some files for test-unit.

The bundle gem -t minitest sample command will generate the following files.

.
|-- Gemfile
|-- README.md
|-- Rakefile
|-- bin
|   |-- console
|   `-- setup
|-- lib
|   |-- sample
|   |   `-- version.rb
|   `-- sample.rb
|-- sample.gemspec  # <- Modify
`-- test
    |-- sample_test.rb # <- Modify
    `-- test_helper.rb # <- Modify

4. Edit files for test-unit

4.1. Edit gemspec

Edit sample.gemspec like the below. Replace minitest line to test-unit.

Before

spec.add_development_dependency "minitest", "~> 5.0"

After

spec.add_development_dependency "test-unit", "~> 3.2.3"

4.2. Edit test/test_helper.rb

Next, edit the test/test_helper.rb file.

Before

$LOAD_PATH.unshift File.expand_path('../../lib', __FILE__)
require 'sample'

require 'minitest/autorun' # <-- Modify this line.

After

$LOAD_PATH.unshift File.expand_path('../../lib', __FILE__)
require 'sample'

require 'test/unit' # <-- After modification.

4.3 Rakefile (No edit)

This file doesn't need to modify. The output is the below.

require "bundler/gem_tasks"
require "rake/testtask"

Rake::TestTask.new(:test) do |t|
  t.libs << "test"
  t.libs << "lib"
  t.test_files = FileList['test/**/*_test.rb']
end

task <code>:default</code> => <code>:test</code>

4.4 Edit test/sample_test.rb

The bundler generate the file test/sample_test.rb. This file originally templates for minitest.

Let's modify this file for test-unit

before

require 'test_helper'

class SampleTest < Minitest::Test # <- Modify here
  def test_that_it_has_a_version_number
    refute_nil ::Sample::VERSION
  end

  def test_it_does_something_useful
    assert false
  end
end

After

require 'test_helper'

class SampleTest < Test::Unit::TestCase # <- After modification
  def test_that_it_has_a_version_number
    refute_nil ::Sample::VERSION
  end

  def test_it_does_something_useful
    assert false
  end
end

5. Execute test.

The rake test command execute test scenarios in the test directory. Now it tries to two tests. One will success the other one fails.

rake test
Loaded suite
/path/to/ruby/lib/ruby/gems/2.3.0/gems/rake-12.0.0/lib/rake/rake_test_loader
Started
F
================================================================================
Failure: <false> is not true.
test_it_does_something_useful(SampleTest)
/path/to/sample/test/sample_test.rb:9:in `test_it_does_something_useful'
      6:   end
      7:
      8:   def test_it_does_something_useful
  =>  9:     assert false
     10:   end
     11: end
================================================================================
.

Finished in 0.011521 seconds.
--------------------------------------------------------------------------------
2 tests, 2 assertions, 1 failures, 0 errors, 0 pendings, 0 omissions, 0 notifications
50% passed
--------------------------------------------------------------------------------
173.60 tests/s, 173.60 assertions/s
rake aborted!
Command failed with status (1)

Tasks: TOP => test
(See full trace by running task with --trace)

6. Create original tests.

Let's create your original tests with the following rules.

Example directory layout.

test
|-- sample_test.rb
|-- sub
|   `-- sample2_test.rb
`-- test_helper.rb

Example test file in the sub directory.

require 'test_helper'

module Sub
  class Sample2Test < Test::Unit::TestCase
    def test_that_it_has_a_version_number
      refute_nil ::Sample::VERSION
    end

    def test_it_does_something_useful
      assert false
    end
  end
end

7. For more information

Let's read the official document.