Pragmatic Test Driven Development

Pragmatic
Test Driven Development
Sunday, January 22, 12

Your Host
Clayton
Lengel-Zigich
clayton@integrumtech.com
Certified Scrum Master
Certified Scrum Product Owner
Certified Scrum Professional
@claytonlz

Types of Testing

Types of Testing
Acceptance
Integration
Unit

Types of Testing
POÄNG
This piece should be 24”
These third-party rubber feet
should fit
Given all of these pieces,
I can sit in the chair

Types of Testing
Acceptance
Unit Unit Unit
Unit Unit Unit
Acceptance

Types of Testing
Feature
Unit Unit Unit
Acceptance
Feature
Unit Unit Unit
Acceptance
Feature
Unit Unit Unit
Acceptance
Feature
Unit Unit Unit
Acceptance
Feature
Unit Unit Unit
Acceptance
Feature
Unit Unit Unit
Acceptance

Who’s Responsible?

QA
QA QA QA QA QA QA QA

QA

Who Writes Unit Tests?

Who Writes Acceptance Tests?
DEV
CUSTOMER
QA
Discovery

Automated Testing

Continuous Integration
Continuous integration avoids or detects compatibility
problems early ... if you integrate throughout the project
in small amounts you will not find your self trying to
integrate the system for weeks at the project's end while
the deadline slips by.
Always work in the context of the latest version of the
system.

Build
Server
SCM
SCM

Build
Server
Compilation
Executes Tests
Defines Status

10
MINUTE BUILD

Test First Programming

Test
Code
Test

Failing
Passing
Refactored

Failing
Acceptance Test
Failing
Unit Test
Passing
Unit Test
Refactor

Code Code Code Code Test Code Code
Time
Code
Test
Time
Code
Test Code
Test Test

Frameworks and Tools

Frameworks And Tools
xUnit

Frameworks And Tools
xUnit Language
JUnit Java
NUnit .Net
TestUnit Ruby
QUnit JavaScript
PhpUnit PHP

Pair Programming

Pair Programming
Write Test Write Code

Tutorial #1

Test Unit Fundamentals
test_strike_strike_ball_ball_ball
test_full_count
vs

Setup
Assertion
Assertion
Assertion
Tear Down

assert(test, msg = (nomsg = true; nil))
assert_equal(exp, act, msg = nil)
assert_no_match(regexp, string, msg=nil)
assert_not_equal(exp, act, msg=nil)
assert_not_nil(exp, msg=nil)
assert_not_same(expected, actual, message="")
assert_nothing_raised(*args)
assert_nothing_thrown(msg=nil)
assert_raise(*args, &b)
assert_respond_to(obj, meth, msg = nil)

TDD RUles
1.Only write code that makes a test pass
2.Only write enough of a test to make it fail
3.Only write enough code to make a test pass

Tutorial #1
In pairs, write a program that can play the game of
hangman.
50m
Activity Time

Mocking & STUBBING
Mocks vs. Stubs
Indirect Outputs vs. Indirect Inputs
Objects vs. Methods
Behavior vs. State

Mocking
Order
Warehouse
?
?
?
Warehouse

Mocking
Order
Warehouse
WarehouseItem
order.items.each do |item|
warehouse_item = Warehouse.find(item)
warehouse_item.stock_reservation.reserve
end
StockReservation

Mocking
Order
Warehouse
Warehouse.reserve(items)

Mocking
fake_warehouse = mock(Warehouse)
assert(
fake_warehouse.received("reserve")
.with(items),
"Expected the warehouse to check its stock"
)

STUBBING
CUSTOMER
“If any items are out-of-stock,
the system should prevent the
order from completing”

STUBBING
def test_out_of_stock
order = Order.new
item1 = Item.new(:sku => "abc")
item2 = Item.new(:sku => "def")
order.items = [item1, item2]
stock_item1 = StockItem.new(:sku => 'zyx')
...
end

STUBBING
def test_invalid_items
Warehouse.stub(:reserve)
.and_raise(OutOfStockException)
assert_raise(OutOfStockException) do
order.complete
end
end

Tutorial #2

Tutorial #2
In pairs, write a program that implements Conway’s
game of life.
45m
Activity Time

Game of Life
“The universe of the Game of Life is an infinite two-
dimensional orthogonal grid of square cells, each of which
is in one of two possible states, alive or dead. Every cell
interacts with its eight neighbors, which are the cells that
are horizontally, vertically, or diagonally adjacent. At each
step in time, the following transitions occur:”

Game of Life: Rules
1
Any live cell with fewer than two live neighbors dies,
as if caused by under-population.
2
Any live cell with two or three live neighbors lives on
to the next generation.
3 Any live cell with more than three live neighbors dies,
as if by overcrowding.
Any dead cell with exactly three live neighbors
becomes a live cell, as if by reproduction.
4

Closing

Test Feedback
Listen to your tests

Code Coverage
DEV
MANAGEMENT
“If we’re not at 90% code
coverage you’re all working
on Saturday.”
“assert(true)”

Continuously Integrate
Live and Die
by the build

Plan to Succeed
Write tests before you plan
the implementation
BDD
Failing
Unit Test
Passing
Unit Test
Refactor
TDD

Pragmatic Test Driven Development

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