Testing outside of the Ruby World

T O
f
Rb W r Joseph Wilk

Sr ...

N R b .

R .

“The number of languages you know
corresponds to your programming
skill”

S

Y ... T
JUnit ScrewUnit
Rspec JBehave
PHPSpec Jasmine
JSpec Cucumber
Circumspec BlahSpec
SomethingSpec WhateverSpec

Y ... T
JUnit ScrewUnit
Rspec BORING!
JBehave
PHPSpec Jasmine
JSpec Cucumber
Circumspec BlahSpec
SomethingSpec WhateverSpec

T &M
Ruby

Monkey.stub!(:new).and_return(mock("monkey"))

Java

I owe you one Java mocking example.

I don’t have the will power to write it.
Sorry.

T &M
Ruby
BORING!
Monkey.stub!(:new).and_return(mock("monkey"))

Java

I owe you one Java mocking example.

I don’t have the will power to write it.
Sorry.

I r
Asynchronous Property testing

Permutation Model testing
explosions

Metrics Test feedback

Graphical tests

“Program testing can be used to show the
presence of bugs, but never to show their
absence!”
Edsger Dijkstra

Q C
Properties

For all values of s the length of the thing
returned by five_random_characters is 5

Q C
Properties

QuickCheck

Randomly
Logic generate Function
tests

Q C
Properties

QuickCheck

Randomly
Logic generate Function
tests

Counter
Examples

Q C
Properties

it "should reverse a string" do
"monkeys".reverse.reverse.should == "monkeys"
end

100.times.map {“#{rand(10)}#{rand(10)}”}.each do |char|
it "should reverse a string" do
char.reverse.reverse.should == char
end
end

Q C
Properties

import Data.Char
import Test.QuickCheck

instance Arbitrary Char where
arbitrary = choose ('32', '128')
coarbitrary c = variant (ord c `rem` 4)

prop_RevRev xs = reverse (reverse xs) == xs
where types = xs::[Char]

$ Main> quickCheck prop_RevRev
OK, passed 100 tests.

Er
Messaging/
Concurrency

M Er Models

Erlang McErlang
runtime runtime
system system

communication

concurrency

distribution

M Er Models

message Messenger
“Scottish
“Scottish Service
fiction”
fiction”

Message login login Message
client client

Fred Clara

M Er Models
if user1 does not send a message m to user2 until user2 is logged on,
then
if user1 does send a message m to user2
then
eventually user2 receives the message m.

"not P until Q => (eventually P => eventually R)”

P: clara sends message “Scottish fiction” to fred
Q: fred is logged on
R: fred receives the message “Scottish fiction” from clara

M Er Models
{program={scenario,start,[[
[{logon,clara},{message,fred,"hi"},logoff],
[{logon,fred},logoff]]]},

monitor={mce_ltl_parse:ltl_string2module_and_load
("not P until Q implies (eventually P implies
eventually R)", messenger_mon),
{void,[{'P',basicPredicates:message_to
(clara,fred,"hi")},
{'Q',basicPredicates:logon(fred)},
{'R',basicPredicates:message_received
(fred,clara,"hi")}]}},
algorithm={mce_alg_buechi,void}}).

“Every method you use to prevent or find
bugs leaves a residue of subtler bugs against
which those methods are ineffectual

Pesticide Paradox / Beizer

M
Facts

(fact
(alive-in-next-generation? ...cell...) => truthy
   (provided
    (alive? ...cell...) => false
    (neighbor-count ...cell...) => 3))

cell = mock("a cell")
cell.stub(:alive?).and_return(false)
cell.stub(:neighbour_count).and_return(3)

cell.alive_in_next_generation.should == true

J v S rp
Without
the Java

Z b .
Trapped inside a browser

Z b .
Trapped inside a browser
var zombie = require("zombie");
var assert = require("assert");

zombie.visit("http://localhost:3000/",
function (err, browser, status) {

browser.
fill("email", "zombie@underworld.dead").
pressButton("Sign Me Up!",
function(err, browser, status) {

assert.equal(browser.text("title"), "Welcome");
})
});

V w
Topics

{ topic: function () { return 42 },

'should be a number': function (topic) {
assert.isNumber (topic);
},
'should be equal to 42': function (topic) {
assert.equal (topic, 42);
}
}

V w
Asynchronous calls

{ topic: function () {
fs.stat('~/FILE', this.callback);
},
'can be accessed': function (err, stat) {
assert.isNull (err); // We have no error
assert.isObject (stat); // We have a stat object
},
'is not empty': function (err, stat) {
assert.isNotZero (stat.size); // The file size is > 0
}
}

V w
Promises / Futures
{ topic: function () {
var promise = new(events.EventEmitter);
fs.stat('~/FILE', function (e, res) {
if (e) { promise.emit('error', e) }
else { promise.emit('success', res) }
});
return promise;
},
'can be accessed': function (err, stat) {
assert.isNull (err); //We have no error
assert.isObject (stat); //We have a stat object
},
'is not empty': function (err, stat) {
assert.isNotZero (stat.size); //The file size is > 0
}
}

V w
Parallel Execution

{ '/dev/stdout': {
topic: function () { path.exists('/dev/stdout',this.callback) },
'exists': function (result) { assert.isTrue(result) }
},
'/dev/tty': {
topic: function () { path.exists('/dev/tty',this.callback) },
},
'/dev/null': {
topic: function () { path.exists('/dev/null',this.callback) },
}
}

J M
Faster Test feedback

Failures are not
randomly distributed

Lots of very short tests
A few very long ones

Kent Beck

J M
Faster Test feedback

I r L
Learn from Metrics

‘‘What is the use of a book,’’ thought Alice,
‘‘without pictures or conversations?’’

Lewis Carroll
Alice’s Adventures in Wonderland

Sw L
Words are not enough

Ward Cunningham

http://vimeo.com/22165070

Ward Cunningham

Gr p T

Brian Marick

‘‘How much do you know about the
heuristics of failure?’

Joseph Wilk
Scotland Ruby Conf 2011

http://testobsessed.com/wp-content/uploads/2007/02/testheuristicscheatsheetv1.pdf

Joseph Wilk
!
@josephwilk
http://blog.josephwilk.net

Testing outside of the Ruby World

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