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<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
<!-- Slide meta data, remove/edit as you see fit -->
<title>RSpec</title>
<meta name="author" content="Kerry Buckley" />
<meta name="email" content="kerry.buckley@gmail.com" />
<meta name="date" content="2011-01-04" />
<meta name="venue" content="Ipswich Ruby User Group" />
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<!-- Slippy init code -->
<script type="text/javascript">
$(function() {
$(".slide").slippy({
});
SyntaxHighlighter.all();
});
</script>
</head>
<body>
<div class="slide">
<h1>RSpec</h1>
<h2 class="center">Kerry Buckley<br />IPRUG, 4 January 2011</h2>
<div class="licence">
<a rel="license" href="http://creativecommons.org/licenses/by-sa/3.0/"><img
class="leavealone"
alt="Creative Commons License"
src="http://i.creativecommons.org/l/by-sa/3.0/88x31.png" /></a>
</div>
<div class="footer">
<span class="left">Use space bar or arrow keys to navigate, and escape for index.</span>
<span class="right">Built with <a href="https://github.com/Seldaek/slippy">Slippy</a>.</span>
</div>
</div>
<div class="slide">
<h1>Why RSpec?</h1>
</div>
<div class="slide">
<h1>Why RSpec?</h1>
<h2>Clear, concise and readable</h2>
<div class="comparison">
<div class="left">
<pre class="brush: ruby">
class StackTest < Test::Unit
def setup
@stack = Stack.new
end
def test_new_is_empty
assert_equal true,
@stack.empty?
end
def test_new_has_size_0
assert_equal 0,
@stack.size
end
end
</pre>
</div>
<div class="middle">
<p>vs</p>
</div>
<div class="right">
<pre class="brush: ruby">
describe Stack do
context "when new" do
it { should be_empty }
it { should have(0).items }
end
end
</pre>
</div>
</div>
</div>
<div class="slide">
<h1>Why RSpec?</h1>
<h2>Documentation</h2>
<div class="vcenter">
<pre>
Stack
when new
<span style="color:green">should be empty</span>
<span style="color:green">should have 0 items</span>
Finished in 0.00089 seconds
<span style="color:green">2 examples, 0 failures</span>
</pre>
</div>
</div>
<div class="slide">
<h1>Gems</h1>
<div class="vcenter">
<ul>
<li>rspec</li>
<li>rspec-core</li>
<li>rspec-expectations</li>
<li>rspec-mocks</li>
<li>rspec-rails</li>
</ul>
</div>
</div>
<div class="slide">
<h1>Basics</h1>
<div class="vcenter">
<pre class="brush: ruby">
describe "Rain" do
it "is wet" do
...
end
end
</pre>
<p><code>specify</code> can also be used in place of <code>it</code>.</p>
</div>
</div>
<div class="slide">
<h1>Contexts</h1>
<div class="vcenter">
<pre class="brush: ruby">
describe "Rain" do
context "in the summer" do
it "is refreshing" do
...
end
end
context "in the winter" do
it "is unpleasant" do
...
end
end
end
</pre>
<p><code>context</code> is an alias for <code>describe</code>.</p>
<p>Use whichever is most appropriate.</p>
</div>
</div>
<div class="slide">
<h1>Describing methods</h1>
<pre class="brush: ruby">
describe MyClass do
describe ".class_method" do
...
end
describe "#instance_method" do
...
end
end
</pre>
<hr />
<p>Documentation output:</p>
<pre>
Myclass.class_method
...
Myclass#instance_method
...
</pre>
</div>
<div class="slide">
<h1>Running</h1>
<div class="vcenter">
<ul>
<li>[bundle exec] rspec</li>
<li>rake</li>
<li>autotest</li>
<li>spork</li>
</ul>
</div>
</div>
<div class="slide">
<h1>Formatters</h1>
<h2>progress (default)</h2>
<div class="vcenter">
<pre>
$ rspec --colour spec/
<span style="color:green">..</span>
Finished in 0.00089 seconds
<span style="color:green">2 examples, 0 failures</span>
</pre>
</div>
</div>
<div class="slide">
<h1>A digression</h1>
<h2>Configuration file</h2>
<div class="vcenter">
<p>We don’t want to type <code>--colour</code> every time!</p>
<p>Put common options in <code>.rspec</code> in the project root.</p>
</div>
</div>
<div class="slide">
<h1>Formatters</h1>
<h2>documentation</h2>
<div class="vcenter">
<pre>
$ rspec -f doc spec/
Stack
when new
<span style="color:green">should be empty</span>
<span style="color:green">should have 0 items</span>
Finished in 0.00089 seconds
<span style="color:green">2 examples, 0 failures</span>
</pre>
</div>
</div>
<div class="slide">
<h1>Formatters</h1>
<h2>html</h2>
<img src="images/html_output.png" alt="HTML output" />
</div>
<div class="slide">
<h1>Formatters</h1>
<h2>Fuubar</h2>
<div class="vcenter">
<p>Fuubar is an external formatter (<code>gem in fuubar</code>).</p>
<pre>
$ rspec -f Fuubar spec/
1) Stack after pushing 1 item
<span style="color:red">Failure/Error: it { should have(1).item }</span>
<span style="color:red">Expected 1 item, got 0</span>
<span style="color:grey"># ./spec/stack_spec.rb:12</span>
<span style="color:red">8/10: 80% |================================ | ETA: 00:00:02</span>
</pre>
</div>
</div>
<div class="slide">
<h1>Formatters</h1>
<h2>Multiple formatters</h2>
<div class="vcenter">
<pre>
$ rspec -f Fuubar -f html -o specs.html spec/
</pre>
</div>
</div>
<div class="slide">
<h1>Profiling</h1>
<pre>
$ rspec --profile spec/
<span style="color:green">55/55: 100% |====================================| Time: 00:00:00</span>
Top 10 slowest examples:
RedRock server allows the port to be overridden
<span style="color:red">0.10258</span> seconds ./spec/redrock_spec.rb:107
RedRock supports specification of a response body as an IO object
<span style="color:red">0.08752</span> seconds ./spec/redrock_spec.rb:336
RedRock returning a custom response returns the specified headers
<span style="color:red">0.07319</span> seconds ./spec/redrock_spec.rb:331
...
</pre>
</div>
<div class="slide">
<h1>Pending specs</h1>
<pre class="brush: ruby">
describe "Something" do
it "does something" do
...
end
it "does something I haven't implemented yet"
end
</pre>
<hr />
<pre>
Something
...
<span style="color:#aa0">does something I haven't implemented yet (PENDING: Not Yet Implemented)</span>
Pending:
<span style="color:#aa0">Something does something I haven't implemented yet</span>
<span style="color:grey"># Not Yet Implemented</span>
<span style="color:grey"># ./spec/something_spec.rb:5</span>
Finished in 0.00052 seconds
<span style="color:#aa0">2 examples, 0 failures, 1 pending</span>
</pre>
</div>
<div class="slide">
<h1>Pending specs</h1>
<pre class="brush: ruby">
describe "Something" do
...
it "does something I haven't implemented yet" do
pending "waiting for inspiration"
...
end
end
</pre>
<hr />
<pre>
Something
...
<span style="color:#aa0">does something I haven't implemented yet (PENDING: waiting for inspiration)</span>
Pending:
<span style="color:#aa0">Something does something I haven't implemented yet</span>
<span style="color:grey"># waiting for inspiration</span>
<span style="color:grey"># ./spec/something_spec.rb:5</span>
Finished in 0.00078 seconds
<span style="color:#aa0">2 examples, 0 failures, 1 pending</span>
</pre>
</div>
<div class="slide">
<h1>Pending specs</h1>
<pre class="brush: ruby">
describe "Something" do
before { pending "Coming soon!" }
it "does something" do
end
it "does something else" do
end
end
</pre>
<hr />
<pre>
Something
<span style="color:#aa0">does something (PENDING: Coming soon!)</span>
<span style="color:#aa0">does something else (PENDING: Coming soon!)</span>
Pending:
<span style="color:#aa0">Something does something</span>
<span style="color:grey"># Coming soon!</span>
<span style="color:grey"># ./spec/something_spec.rb:4</span>
<span style="color:#aa0">Something does something else</span>
<span style="color:grey"># Coming soon!</span>
<span style="color:grey"># ./spec/something_spec.rb:7</span>
Finished in 0.0114 seconds
<span style="color:#aa0">2 examples, 0 failures, 2 pending</span>
</pre>
</div>
<div class="slide">
<h1>Running one spec</h1>
<div class="vcenter">
<pre class="brush: ruby">
describe "Something" do
it "does stuff" do ...
it "does other stuff" do ...
it "does one more thing" do ...
end
</pre>
<hr />
<pre>
$ rspec -f doc spec/something_spec.rb:5
Run filtered using {:line_number=>5}
Something
<span style="color:green">does other stuff</span>
Finished in 0.00036 seconds
<span style="color:green">1 example, 0 failures</span>
</pre>
</div>
</div>
<div class="slide">
<h1>Filtering by tag</h1>
<div class="vcenter">
<pre class="brush: ruby">
describe "Something" do
it "does stuff" do
...
end
it "does the thing I'm working on", :current => true do
...
end
end
</pre>
<hr />
<p>Run only specs tagged ‘current’</p>
<pre>
rspec --tag current ...
</pre>
<p>Run specs <em>not</em> tagged ‘current’</p>
<pre>
rspec --tag ~current ...
</pre>
</div>
</div>
<div class="slide">
<h1>Filtering by tag value</h1>
<div class="vcenter">
<pre class="brush: ruby">
describe "Something" do
it "behaves one way in Ruby 1.8", :ruby => "1.8" do
...
end
it "behaves another way in Ruby 1.9", :ruby => "1.9" do
...
end
end
</pre>
<hr />
<p>Run 1.8 specs:</p>
<pre>
rspec --tag ruby:1.8
</pre>
</div>
</div>
<div class="slide">
<h1>Implicit filtering</h1>
<div class="vcenter">
<pre class="brush: ruby">
RUBY_1_9 = (RUBY_VERSION =~ /^1\.9/)
describe "Something" do
it "does this when using 1.9", :if => RUBY_1_9 do
...
end
it "Does that when not using 1.9", :unless => RUBY_1_9 do
...
end
end
</pre>
</div>
</div>
<div class="slide">
<h1>Filtering by name</h1>
<pre class="brush: ruby">
describe "Something" do
it "does stuff" do ...
it "does other stuff" do ...
it "does one more thing" do ...
end
</pre>
<hr />
<p>Select specs using a regular expression:</p>
<pre>
$ rspec -e stuff spec/something_spec.rb
Run filtered using {:full_description=>/(?-mix:stuff)/}
Something
<span style="color:green">does stuff</span>
<span style="color:green">does other stuff</span>
Finished in 0.00101 seconds
<span style="color:green">2 examples, 0 failures</span>
</pre>
</div>
<div class="slide">
<h1>Setup and teardown</h1>
<div class="vcenter">
<pre class="brush: ruby">
describe "Something" do
before :all do
# per-context setup
end
before do
# per-example setup
end
after do
# per-example teardown
end
after :all do
# per-context teardown
end
end
</pre>
</div>
</div>
<div class="slide">
<h1>Expectations</h1>
<div class="vcenter">
<p>RSpec adds <code>should</code> and <code>should_not</code> to all objects.</p>
<pre class="brush: ruby">
(2 + 2).should == 4
"foo".should_not == "bar"
value.should be_true
</pre>
<p>The <code>==</code> and <code>be_true</code> are <em>matchers</em>.</p>
</div>
</div>
<div class="slide">
<h1>Built-in matchers</h1>
<h2>Equality</h2>
<div class="vcenter">
<pre class="brush: ruby">
a.should equal(b) # both pass if a.equal? b
a.should be(b) #
a.should eql(b) # passes if a.eql? b
a.should == b # both pass if a == b
a.should eq(b) #
</pre>
</div>
</div>
<div class="slide">
<h1>Built-in matchers</h1>
<h2>Floating point</h2>
<div class="vcenter">
<pre class="brush: ruby">
Math::PI.should be_within(0.01).of(22.0/7)
</pre>
</div>
</div>
<div class="slide">
<h1>Built-in matchers</h1>
<h2>True or false</h2>
<div class="vcenter">
<pre class="brush: ruby">
obj.should be_true # passes if obj is truthy (not nil or false)
obj.should be_false # passes if obj is falsy (nil or false)
obj.should be_nil # passes if obj is nil
obj.should be # passes if obj is not nil
</pre>
<p><code>should be</code> is preferred to <code>should_not be_nil</code>.</p>
</div>
</div>
<div class="slide">
<h1>Built-in matchers</h1>
<h2>Operators</h2>
<div class="vcenter">
<pre class="brush: ruby">
7.should == 7
[1, 2, 3].should == [1, 2, 3]
"this is a string".should =~ /^this/
"this is a string".should_not =~ /^that/
String.should === "this is a string"
</pre>
<p>Comparison operators work with the "be" matcher:</p>
<pre class="brush: ruby">
37.should be < 100
37.should be <= 38
37.should be >= 2
37.should be > 7
</pre>
</div>
</div>
<div class="slide">
<h1>Built-in matchers</h1>
<h2>Collections</h2>
<pre class="brush: ruby">
# These two are identical:
[1, 2, 3].should have(3).items
[1, 2, 3].should have_exactly(3).items
[1, 2, 3].should have_at_least(2).items
[1, 2, 3].should have_at_most(4).items
# "items" is just syntactic sugar:
[1, 2, 3].should have(3).numbers
[1, 2, 3].should include(2)
[1, 2, 3].should include(1, 2)
{:a => 1, :b => 2}.should include(:a => 1)
[1, 2, 3].should =~ [2, 3, 1]
[:a, :c, :b].should_not =~ [:a, :c]
</pre>
</div>
<div class="slide">
<h1>Built-in matchers</h1>
<h2>Strings</h2>
<div class="vcenter">
<pre class="brush: ruby">
"This is a string".should include "str"
# These two are identical:
"This is a string".should =~ /^This/
"This is a string".should match(/^This/)
</pre>
</div>
</div>
<div class="slide">
<h1>Another digression</h1>
<h2>Failure messages</h2>
<div class="vcenter">
<p>The default messages are usually pretty good:</p>
<pre class="brush: ruby">
(2 + 2).should == 5
[1, 2, 3].should =~ [4, 3, 2]
</pre>
<hr />
<pre>
<span style="color:red">Failure/Error: (2 + 2).should == 5
expected: 5
got: 4 (using ==)
Failure/Error: [1, 2, 3].should =~ [4, 3, 2]
expected collection contained: [2, 3, 4]
actual collection contained: [1, 2, 3]
the missing elements were: [4]
the extra elements were: [1]</span>
</pre>
</div>
</div>
<div class="slide">
<h1>Another digression</h1>
<h2>Failure messages</h2>
<div class="vcenter">
<p>…but you can use a custom message if you like<sup>*</sup>:</p>
<pre class="brush: ruby">
it "includes 3" do
[1, 2, 3].should include(3), "Oh noes! No three!"
end
</pre>
<hr />
<pre>
1) Something includes 3
<span style="color:red">Failure/Error: [1, 2, 4].should include(3), "Oh noes! No three!"
Oh noes! No three!</span>
</pre>
<p><sup>*</sup>except with operator matchers (<code>==</code> etc).</p>
</div>
</div>
<div class="slide">
<h1>Back to built-in matchers</h1>
<h2>Predicates</h2>
<div class="comparison">
<div class="left">
<pre class="brush: ruby">
[].empty?.should be_true
42.even?.should be_true
123.multiple_of?(5).
should be_false
{:a => 1, :b => 2}.has_key?(:a).
should be_true
</pre>
</div>
<div class="middle">
<p>➧</p>
</div>
<div class="right">
<pre class="brush: ruby">
[].should be_empty
42.should be_even
123.should_not be_multiple_of(5)
{:a => 1, :b => 2}.
should have_key(:a)
</pre>
</div>
</div>
</div>
<div class="slide">
<h1>Built-in matchers</h1>
<h2>Classes</h2>
<div class="vcenter">
<pre class="brush: ruby">
"foo".should be_an_instance_of(String) # Exact class
"foo".should_not be_an_instance_of(Object) #
"foo".should be_a_kind_of(Object) # Match subclasses
"foo".should be_an(Object) #
"foo".should respond_to(:upcase)
"foo".should respond_to(:upcase, :downcase)
"foo".should respond_to(:upcase).with(0).arguments
</pre>
</div>
</div>
<div class="slide">
<h1>Built-in matchers</h1>
<h2>Changing values</h2>
<div class="vcenter">
<pre class="brush: ruby">
expect{ array << 42 }.to change{ array.size }.from(0).to(1)
expect{ array << 42 }.to change{ array.size }.by(1)
</pre>
</div>
</div>
<div class="slide">
<h1>Built-in matchers</h1>
<h2>Raising and throwing</h2>
<div class="vcenter">
<pre class="brush: ruby">
expect { 4/2 }.to_not raise_error
expect { 4/0 }.to raise_error
expect { 4/0 }.to raise_error(ZeroDivisionError)
expect { 4/0 }.to raise_error(ZeroDivisionError, "divided by 0")
expect { throw :foo }.to throw_symbol
expect { throw :foo }.to throw_symbol(:foo)
expect { throw :foo, 7 }.to throw_symbol(:foo, 7)
</pre>
</div>
</div>
<div class="slide">
<h1>Built-in matchers</h1>
<h2>Exist</h2>
<div class="vcenter">
<pre class="brush: ruby">
obj.should exist # passes if obj.exist? returns true
</pre>
<p>This is the only use case I could think of:</p>
<pre class="brush: ruby">
Pathname("/etc/passwd").should exist
</pre>
</div>
</div>
<div class="slide">
<h1>Built-in matchers</h1>
<h2>Arbitrary blocks</h2>
<div class="vcenter">
<pre class="brush: ruby">
10.should satisfy { |v| v % 5 == 0 }
</pre>
<p>Not really recommended, because of the unfriendly failure message:</p>
<pre>
<span style="color:red">Failure/Error: 11.should satisfy { |v| v % 5 == 0 }</span>
<span style="color:red">expected 11 to satisfy block</span>
</pre>
<p>Which brings us to…</p>
</div>
</div>
<div class="slide">
<h1>Custom matchers</h1>
<pre class="brush: ruby">
RSpec::Matchers.define :be_a_multiple_of do |expected|
match do |actual|
actual % expected == 0
end
end
describe 10 do
it { should be_a_multiple_of(5) }
end
</pre>
<hr />
<pre>
10
<span style="color:green">should be a multiple of 5</span>
Finished in 0.04768 seconds
<span style="color:green">1 example, 0 failures</span>
</pre>
</div>
<div class="slide">
<h1>Hang on a minute…</h1>
<pre class="brush: ruby">
RSpec::Matchers.define :be_a_multiple_of do |expected|
match do |actual|
actual % expected == 0
end
end
describe 10 do
it { should be_a_multiple_of(5) }
end
</pre>
<hr />
<pre>
10
<span style="color:green">should be a multiple of 5</span>
Finished in 0.04768 seconds
<span style="color:green">1 example, 0 failures</span>
</pre>
<p>Firstly, note how a description has been automatically generated for us.</p>
<p>But what are we calling <code>should</code> on?</p>
</div>
<div class="slide">
<h1>Implicit subject</h1>
<p>The argument to <code>describe</code> becomes the subject:</p>
<pre class="brush: ruby">
describe 42 do
it { should be_even }
it { should_not be_zero }
end
</pre>
<p>If it’s a class, the subject is a new instance:</p>
<pre class="brush: ruby">
describe Array do
it { should be_empty }
it { should have(0).items }
end
</pre>
</div>
<div class="slide">
<h1>Implicit subject</h1>
<p>Access attributes of the subject with <code>its</code>:</p>
<pre class="brush: ruby">
describe [1, 2, 3, 3] do
its(:size) { should == 4 }
its("uniq.size") { should == 3 }
end
</pre>
<hr />
<pre>
1233
size
<span style="color:green">should == 4</span>
uniq.size
<span style="color:green">should == 3</span>
Finished in 0.00279 seconds
<span style="color:green">2 examples, 0 failures</span>
</pre>
<p>That description (from <code>to_s</code>) could be better...</p>
</div>
<div class="slide">
<h1>Explicit subject</h1>
<p>You can set the subject explicitly using a block:</p>
<pre class="brush: ruby">
describe "An array containing 1, 2, 3, 3" do
subject { [1, 2, 3, 3] }
its(:size) { should == 4 }
end
</pre>
<p>And access it in examples as <code>subject</code>:</p>
<pre class="brush: ruby">
describe Array do
it "is empty" do
subject.should be_empty
end
end
</pre>
</div>
<div class="slide">
<h1>Custom matchers</h1>
<p>You can override the description and failure messages:</p>
<pre class="brush: ruby">
RSpec::Matchers.define :be_a_multiple_of do |expected|
match do |actual|
actual % expected == 0
end
failure_message_for_should do |actual|
"expected that #{actual} would be a multiple of #{expected}"
end
failure_message_for_should_not do |actual|
"expected that #{actual} would not be a multiple of #{expected}"
end
description do
"be multiple of #{expected}"
end
end
</pre>
</div>
<div class="slide">
<h1>Custom matchers</h1>
<p>Not all matchers take an argument:</p>
<pre class="brush: ruby">
RSpec::Matchers.define :be_a_multiple_of_3 do
match do |number|
number % 3 == 0
end
end
</pre>
</div>
<div class="slide">
<h1>Shoulda matchers</h1>
<p><a href="https://github.com/thoughtbot/shoulda">Shoulda</a> provides a whole bunch of Rails matchers, including:</p>
<pre class="brush: ruby">
it { should render_template(:show) }
it { should assign_to(:user).with(@user) }
it { should redirect_to(users_path) }
it { should render_with_layout(:special) }
it { should respond_with(:success) }
it { should route(:get, "/posts/new").to(:action => :new) }
it { should set_the_flash.to(/created/i) }
it { should validate_presence_of(:name) }
it { should_not allow_mass_assignment_of(:password) }
it { should have_one(:profile) }
it { should have_db_column(:salary).of_type(:decimal) }
</pre>
</div>
<div class="slide">
<h1>Speaking of shoulda…</h1>
<blockquote>Shoulda is focusing on the RSpec/Shoulda combination and will
primarily support that combination of tools, moving away from
Test::Unit.</blockquote>
<p><em><a href="http://robots.thoughtbot.com/post/701863189/shoulda-rails3-and-beyond">Thoughtbot blog</a>, June 2010</em></p>
</div>
<div class="slide">
<h1>Let there be let</h1>
<p>These examples have some duplication…</p>
<pre class="brush: ruby">
describe BowlingGame do
it "scores all gutters with 0" do
game = BowlingGame.new
20.times { game.roll(0) }
game.score.should == 0
end
it "scores all 1s with 20" do
game = BowlingGame.new
20.times { game.roll(1) }
game.score.should == 20
end
end
</pre>
</div>
<div class="slide">
<h1>Let there be let</h1>
<p>We could move it into a <code>before</code> block…</p>
<pre class="brush: ruby">
describe BowlingGame do
before do
@game = BowlingGame.new
end
it "scores all gutters with 0" do
20.times { @game.roll(0) }
@game.score.should == 0
end
it "scores all 1s with 20" do
20.times { @game.roll(1) }
@game.score.should == 20
end
end
</pre>
</div>
<div class="slide">