Unit testing Ch. 13 of Programming Ruby

Unit Testing

Programming Ruby 1.9
Chapter 13

What is it?

●testing at the lowest level
●individual methods or lines
within methods

Why?

●less "archaeology"
●decoupled designs

●peace of mind when
refactoring

MiniTest::Unit vs Test::Unit

require 'minitest/unit'
● MiniTest new in 1.9 "a little leaner"
● has a compatibility layer for Test::Unit
● negative assertions renamed to refute
○ assert_not_nil -> refute_nil
● missing assertions
○ assert_not_raises
○ assert_not_throws
require 'test/unit'
● most of the features people used
gem install test-unit
● little used features: test cases, GUI runners

Example Test

require_relative 'romanbug'
require 'test/unit'

class TestRoman < Test::Unit::TestCase
def test_simple
assert_equal "i", Roman.new(1).to_s
assert_equal "ix", Roman.new(9).to_s
end
end

Structuring Tests

● prefix methods with test_
● setup/teardown run before/after each test
○ use passed? in teardown to see if the test
passed

Running Tests (files in the same folder)

● ruby test_roman.rb
○ Kernel::at_exit
● ruby test_roman.rb -n test_simple
● ruby test_roman.rb -n /simple/

Organizing tests

roman/
lib/
roman.rb
other files....

test/
test_roman.rb
other tests....

other files....

Running Tests (standard structure)

● ruby -I path/to/app/lib
path/to/app/test/test_roman.rb
● ruby -I lib test/test_roman.rb

RSpec

● write story before writing tests
● special .should semantics

RSpec Example

require_relative 'tennis_scorer'

describe TennisScorer do
it "should start with a score of 0-0" do
ts = TennisScorer.new
ts.score.should == "0-0"
end
it "should be 15-0 if the server wins a point"
end

RSpec

before(:each), before(:all), after(:each), after(:all)

Shoulda

● less opinionated than RSpec
● code lives inside Test::Unit::TestCases
● makes test cases, so Test::Unit assertions work

Shoulda Example

require 'test/unit'
require 'shoulda'
require_relative 'tennis_scorer.rb'

class TennisScorerTest < Test::Unit::TestCase
context "Tennis scores" do
setup do
@ts = TennisScorer.new
end
should "start with a score of 0-0" do
assert_equal("0-0", @ts.score)
end
end
end

Shoulda

● contexts may be nested
● setup, should, should_eventually, teardown

Unit testing Ch. 13 of Programming Ruby

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