minitest/{unit,spec,mock,benchmark}

home

github.com/seattlerb/minitest

bugs

github.com/seattlerb/minitest/issues

rdoc

docs.seattlerb.org/minitest

vim

github.com/sunaku/vim-ruby-minitest

emacs

github.com/arthurnn/minitest-emacs

DESCRIPTION:

minitest provides a complete suite of testing facilities supporting TDD, BDD, mocking, and benchmarking.

"I had a class with Jim Weirich on testing last week and we were
 allowed to choose our testing frameworks. Kirk Haines and I were
 paired up and we cracked open the code for a few test
 frameworks...

 I MUST say that minitest is *very* readable / understandable
 compared to the 'other two' options we looked at. Nicely done and
 thank you for helping us keep our mental sanity."

-- Wayne E. Seguin

minitest/unit is a small and incredibly fast unit testing framework. It provides a rich set of assertions to make your tests clean and readable.

minitest/spec is a functionally complete spec engine. It hooks onto minitest/unit and seamlessly bridges test assertions over to spec expectations.

minitest/benchmark is an awesome way to assert the performance of your algorithms in a repeatable manner. Now you can assert that your newb co-worker doesn't replace your linear algorithm with an exponential one!

minitest/mock by Steven Baker, is a beautifully tiny mock (and stub) object framework.

minitest/pride shows pride in testing and adds coloring to your test output. I guess it is an example of how to write IO pipes too. :P

minitest/unit is meant to have a clean implementation for language implementors that need a minimal set of methods to bootstrap a working test suite. For example, there is no magic involved for test-case discovery.

"Again, I can't praise enough the idea of a testing/specing
 framework that I can actually read in full in one sitting!"

-- Piotr Szotkowski

Comparing to rspec:

rspec is a testing DSL. minitest is ruby.

-- Adam Hawkins, "Bow Before MiniTest"

minitest doesn't reinvent anything that ruby already provides, like: classes, modules, inheritance, methods. This means you only have to learn ruby to use minitest and all of your regular OO practices like extract-method refactorings still apply.

FEATURES/PROBLEMS:

RATIONALE:

See design_rationale.rb to see how specs and tests work in minitest.

SYNOPSIS:

Given that you'd like to test the following class:

class Meme
  def i_can_has_cheezburger?
    "OHAI!"
  end

  def will_it_blend?
    "YES!"
  end
end

Unit tests

Define your tests as methods beginning with `test_`.

require "minitest/autorun"

class TestMeme < Minitest::Test
  def setup
    @meme = Meme.new
  end

  def test_that_kitty_can_eat
    assert_equal "OHAI!", @meme.i_can_has_cheezburger?
  end

  def test_that_it_will_not_blend
    refute_match /^no/i, @meme.will_it_blend?
  end

  def test_that_will_be_skipped
    skip "test this later"
  end
end

Specs

require "minitest/autorun"

describe Meme do
  before do
    @meme = Meme.new
  end

  describe "when asked about cheeseburgers" do
    it "must respond positively" do
      @meme.i_can_has_cheezburger?.must_equal "OHAI!"
    end
  end

  describe "when asked about blending possibilities" do
    it "won't say no" do
      @meme.will_it_blend?.wont_match /^no/i
    end
  end
end

For matchers support check out:

github.com/zenspider/minitest-matchers

Benchmarks

Add benchmarks to your tests.

# optionally run benchmarks, good for CI-only work!
require "minitest/benchmark" if ENV["BENCH"]

class TestMeme < Minitest::Benchmark
  # Override self.bench_range or default range is [1, 10, 100, 1_000, 10_000]
  def bench_my_algorithm
    assert_performance_linear 0.9999 do |n| # n is a range value
      @obj.my_algorithm(n)
    end
  end
end

Or add them to your specs. If you make benchmarks optional, you'll need to wrap your benchmarks in a conditional since the methods won't be defined. In minitest 5, the describe name needs to match /Bench(mark)?$/.

describe "Meme Benchmark" do
  if ENV["BENCH"] then
    bench_performance_linear "my_algorithm", 0.9999 do |n|
      100.times do
        @obj.my_algorithm(n)
      end
    end
  end
end

outputs something like:

# Running benchmarks:

TestBlah      100     1000    10000
bench_my_algorithm     0.006167        0.079279        0.786993
bench_other_algorithm  0.061679        0.792797        7.869932

Output is tab-delimited to make it easy to paste into a spreadsheet.

Mocks

class MemeAsker
  def initialize(meme)
    @meme = meme
  end

  def ask(question)
    method = question.tr(" ","_") + "?"
    @meme.__send__(method)
  end
end

require "minitest/autorun"

describe MemeAsker do
  before do
    @meme = Minitest::Mock.new
    @meme_asker = MemeAsker.new @meme
  end

  describe "#ask" do
    describe "when passed an unpunctuated question" do
      it "should invoke the appropriate predicate method on the meme" do
        @meme.expect :will_it_blend?, :return_value
        @meme_asker.ask "will it blend"
        @meme.verify
      end
    end
  end
end

Stubs

def test_stale_eh
  obj_under_test = Something.new

  refute obj_under_test.stale?

  Time.stub :now, Time.at(0) do   # stub goes away once the block is done
    assert obj_under_test.stale?
  end
end

A note on stubbing: In order to stub a method, the method must actually exist prior to stubbing. Use a singleton method to create a new non-existing method:

def obj_under_test.fake_method
  ...
end

Running Your Tests

Ideally, you'll use a rake task to run your tests, either piecemeal or all at once. Both rake and rails ship with rake tasks for running your tests. BUT! You don't have to:

% ruby -Ilib:test test/minitest/test_minitest_unit.rb 
Run options: --seed 37685

# Running:

...................................................................... (etc)

Finished in 0.107130s, 1446.8403 runs/s, 2959.0217 assertions/s.

155 runs, 317 assertions, 0 failures, 0 errors, 0 skips

There are runtime options available, both from minitest itself, and also provided via plugins. To see them, simply run with `–help`:

% ruby -Ilib:test test/minitest/test_minitest_unit.rb --help
minitest options:
    -h, --help                       Display this help.
    -s, --seed SEED                  Sets random seed
    -v, --verbose                    Verbose. Show progress processing files.
    -n, --name PATTERN               Filter run on /pattern/ or string.

Known extensions: pride, autotest
    -p, --pride                      Pride. Show your testing pride!
    -a, --autotest                   Connect to autotest server.

Writing Extensions

To define a plugin, add a file named minitest/XXX_plugin.rb to your project/gem. Minitest will find and require that file using Gem.find_files. It will then try to call plugin_XXX_init during startup. The option processor will also try to call plugin_XXX_options passing the OptionParser instance and the current options hash. This lets you register your own command-line options. Here's a totally bogus example:

# minitest/bogus_plugin.rb:

module Minitest
  def self.plugin_bogus_options(opts, options)
    opts.on "--myci", "Report results to my CI" do
      options[:myci] = true
      options[:myci_addr] = get_myci_addr
      options[:myci_port] = get_myci_port
    end
  end

  def self.plugin_bogus_init(options)
    self.reporter << MyCI.new(options) if options[:myci]
  end
end

Adding custom reporters

Minitest uses composite reporter to output test results using multiple reporter instances. You can add new reporters to the composite during the init_plugins phase. As we saw in plugin_bonus_init above, you simply add your reporter instance to the composite via +<<+.

AbstractReporter defines the API for reporters. You may subclass it and override any method you want to achieve your desired behavior.

start

Called when the run has started.

record

Called for each result, passed or otherwise.

report

Called at the end of the run.

passed?

Called to see if you detected any problems.

Using our example above, here is how we might implement MyCI:

# minitest/bogus_plugin.rb

module Minitest
  class MyCI < AbstractReporter
    attr_accessor :results, :addr, :port

    def initialize options
      self.results = []
      self.addr = options[:myci_addr]
      self.port = options[:myci_port]
    end

    def record result
      self.results << result
    end

    def report
      CI.connect(addr, port).send_results self.results
    end
  end
end

FAQ

How to test SimpleDelegates?

The following implementation and test:

class Worker < SimpleDelegator
  def work
  end
end

describe Worker do
  before do
    @worker = Worker.new(Object.new)
  end

  it "must respond to work" do
    @worker.must_respond_to :work
  end
end

outputs a failure:

  1) Failure:
Worker#test_0001_must respond to work [bug11.rb:16]:
Expected #<Object:0x007f9e7184f0a0> (Object) to respond to #work.

Worker is a SimpleDelegate which in 1.9+ is a subclass of BasicObject. Expectations are put on Object (one level down) so the Worker (SimpleDelegate) hits `method_missing` and delegates down to the `Object.new` instance. That object doesn't respond to work so the test fails.

You can bypass `SimpleDelegate#method_missing` by extending the worker with `Minitest::Expectations`. You can either do that in your setup at the instance level, like:

before do
  @worker = Worker.new(Object.new)
  @worker.extend Minitest::Expectations
end

or you can extend the Worker class (within the test file!), like:

class Worker
  include ::Minitest::Expectations
end

How to share code across test classes?

Use a module. That's exactly what they're for:

module UsefulStuff
  def useful_method
    # ...
  end
end

describe Blah do
  include UsefulStuff

  def test_whatever
    # useful_method available here
  end
end

Remember, `describe` simply creates test classes. It's just ruby at the end of the day and all your normal Good Ruby Rules (tm) apply. If you want to extend your test using setup/teardown via a module, just make sure you ALWAYS call super. before/after automatically call super for you, so make sure you don't do it twice.

Prominent Projects using Minitest:

Known Extensions:

capybara_minitest_spec

Bridge between Capybara RSpec matchers and Minitest::Spec expectations (e.g. page.must_have_content(“Title”)).

minispec-metadata

Metadata for describe/it blocks (e.g. `it “requires JS driver”, js: true do`)

minitest-ansi

Colorize minitest output with ANSI colors.

minitest-around

Around block for minitest. An alternative to setup/teardown dance.

minitest-capistrano

Assertions and expectations for testing Capistrano recipes.

minitest-capybara

Capybara matchers support for minitest unit and spec.

minitest-chef-handler

Run Minitest suites as Chef report handlers

minitest-ci

CI reporter plugin for Minitest.

minitest-colorize

Colorize Minitest output and show failing tests instantly.

minitest-context

Defines contexts for code reuse in Minitest specs that share common expectations.

minitest-debugger

Wraps assert so failed assertions drop into the ruby debugger.

minitest-display

Patches Minitest to allow for an easily configurable output.

minitest-documentation

Minimal documentation format inspired by rspec's.

minitest-doc_reporter

Detailed output inspired by rspec's documentation format.

minitest-emoji

Print out emoji for your test passes, fails, and skips.

minitest-english

Semantically symmetric aliases for assertions and expectations.

minitest-excludes

Clean API for excluding certain tests you don't want to run under certain conditions.

minitest-filesystem

Adds assertion and expectation to help testing filesystem contents.

minitest-firemock

Makes your Minitest mocks more resilient.

minitest-great_expectations

Generally useful additions to minitest's assertions and expectations.

minitest-growl

Test notifier for minitest via growl.

minitest-implicit-subject

Implicit declaration of the test subject.

minitest-instrument

Instrument ActiveSupport::Notifications when test method is executed.

minitest-instrument-db

Store information about speed of test execution provided by minitest-instrument in database.

minitest-libnotify

Test notifier for minitest via libnotify.

minitest-line

Run test at line number.

minitest-macruby

Provides extensions to minitest for macruby UI testing.

minitest-matchers

Adds support for RSpec-style matchers to minitest.

minitest-metadata

Annotate tests with metadata (key-value).

minitest-mongoid

Mongoid assertion matchers for Minitest.

minitest-must_not

Provides must_not as an alias for wont in Minitest.

minitest-nc

Test notifier for minitest via Mountain Lion's Notification Center.

minitest-parallel-db

Run tests in parallel with a single database.

minitest-power_assert

PowerAssert for Minitest.

minitest-predicates

Adds support for .predicate? methods.

minitest-rails

Minitest integration for Rails 3.x.

minitest-rails-capybara

Capybara integration for Minitest::Rails.

minitest-reporters

Create customizable Minitest output formats.

minitest-rg

Colored red/green output for Minitest.

minitest-rspec_mocks

Use RSpec Mocks with Minitest.

minitest-should_syntax

RSpec-style +x.should == y+ assertions for Minitest.

minitest-shouldify

Adding all manner of shoulds to Minitest (bad idea)

minitest-spec-context

Provides rspec-ish context method to Minitest::Spec.

minitest-spec-expect

Expect syntax for Minitest::Spec (e.g. expect(sequences).to_include :celery_man).

minitest-spec-magic

Minitest::Spec extensions for Rails and beyond.

minitest-spec-rails

Drop in Minitest::Spec superclass for ActiveSupport::TestCase.

minitest-stub_any_instance

Stub any instance of a method on the given class for the duration of a block.

minitest-stub-const

Stub constants for the duration of a block.

minitest-tags

Add tags for minitest.

minitest-vcr

Automatic cassette managment with Minitest::Spec and VCR.

minitest-wscolor

Yet another test colorizer.

minitest_owrapper

Get tests results as a TestResult object.

minitest_should

Shoulda style syntax for minitest test::unit.

minitest_tu_shim

Bridges between test/unit and minitest.

mongoid-minitest

Minitest matchers for Mongoid.

pry-rescue

A pry plugin w/ minitest support. See pry-rescue/minitest.rb.

rspec2minitest

Easily translate any RSpec matchers to Minitest assertions and expectations.

Unknown Extensions:

Authors… Please send me a pull request with a description of your minitest extension.

REQUIREMENTS:

INSTALL:

sudo gem install minitest

On 1.9, you already have it. To get newer candy you can still install the gem, and then requiring “minitest/autorun” should automatically pull it in. If not, you'll need to do it yourself:

gem "minitest"     # ensures you"re using the gem, and not the built-in MT
require "minitest/autorun"

# ... usual testing stuffs ...

DO NOTE: There is a serious problem with the way that ruby 1.9/2.0 packages their own gems. They install a gem specification file, but don't install the gem contents in the gem path. This messes up Gem.find_files and many other things (gem which, gem contents, etc).

Just install minitest as a gem for real and you'll be happier.

LICENSE:

(The MIT License)

Copyright © Ryan Davis, seattle.rb

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.