The document discusses unit testing in software development, emphasizing its importance in identifying and fixing bugs early by testing small pieces of code. It provides examples and best practices for writing effective unit tests, highlighting the need for tests to be automated, repeatable, and focused on the functionality of the code. Additionally, it outlines common pitfalls and how to structure tests using frameworks like PHPUnit.

1. From typing the test to testing the type Wim Godden Cu.be Solutions User meeting Aug 25, 2010

2. About me Wim Godden

3. PHP developer since 1997 (PHP/FI 2.0)

4. ZCE and ZFCE

5. Developer of OpenX

6. Owner of Cu.be Solutions

7. Currently : PHP Architect @ NMBS

8. About you Developers ? Managers ?

9. OOP experience ?

10. Testing : What is unit testing ?

11. Have you written any ?

12. Brief agenda What's unit testing ?

13. How does it work ?

14. When and how to test

15. A complete example (with some pitfalls)

16. Some hints & tips along the way

17. Testing the type

18. This is not... a full tutorial on unit testing

19. a complete step-by-step guide

20. a typical unit testing presentation (as you'll notice...)

21. -> Plenty of online resources, tutorials, conference talks, etc. about the regular stuff

22. What's unit testing ? <Wikipedia> Unit testing is a software design and development method where the programmer gains confidence that individual units of source code are fit for use. </Wikipedia>

23. What's unit testing ? <Wikipedia> Unit testing is a software design and development method where the programmer gains confidence that individual units of source code are fit for use. </Wikipedia>

24. What's a unit ? <?php class Fridge { protected $beerBottles ; public function getBeerSupply() { return $this ->beerBottles; } public function addBeer( $bottles ) { $this ->beerBottles += $bottles ; return true ; } public function drinkBeer( $bottles ) { $this ->beerBottles -= $bottles ; return true ; } }

25. Why unit test ? Write code

26. Add code

27. Add more code

28. At some point you will break something Misspelling

29. Typos (= instead of == in an if-statement)

30. Backwards logic (== instead of !=, < instead of >)

31. etc. So what do you do ? -> You look for the bug !

32. Why unit test ? So what happens when you find that bug ? You fix it of course... Only to find that you just caused 6 other things to break

33. Why unit test ? You test the smallest piece of code

34. -> if a test fails, you know exactly where to look

35. Early detection of bugs

36. Tests are : automated

37. repeatable

38. consistent Functional tests -> “something's wrong” -> but where ?

39. Unit tests -> “this is what's wrong in this piece of code”

40. A simple example <?php class Fridge { protected $beerBottles ; public function addBeer( $bottles ) { $this ->beerBottles += $bottles ; return true ; } public function drinkBeer( $bottles ) { if ( $bottles >= $this ->beerBottles) { $this ->beerBottles -= $bottles ; return true ; } else { // We ran out of beer ! // $wive->sendToStore($beer, 'a lot'); return false ; } } public function getBeerSupply() { return $this ->beerBottles; } } <?php class FridgeTest extends PHPUnit_Framework_TestCase { private $fridge ; public function testAddBeer() { $this ->fridge = new Fridge(); $this ->assertTrue( $this ->fridge->addBeer( 15 )); } public function testDrinkBeer() { $this ->fridge = new Fridge(); $this ->assertTrue( $this ->fridge->drinkBeer( 15 )); } public function testGetBeerSupply() { $this ->fridge = new Fridge(); $this ->assertType( 'integer' , $this ->fridge->getBeerSupply() ); } }

41. How does it work ?

42. Running the test > phpunit <test-filename.php>

43. Output :

44. ...

45. Time: 0 seconds

46. OK (3 tests, 3 assertions)

47. Assertions AssertEquals

48. AssertTrue

49. AssertFalse

50. AssertType

51. AssertGreaterThan

52. AssertNotNull

53. …

54. You can also add your own !

55. Test case environment Each test must be run in an identical environment

56. Tests should run independent of the result of a previous test

57. How ?  Fixtures setUp() : creates the initial state

58. tearDown() : destroys the state

59. Fixtures Test1 Starts with empty fridge

60. Fill the fridge with 15 beers

61. Run the test (take 14 beers) Test2 Starts with 1 beer in fridge

62. Fill the fridge with 15 beers

63. Run the test (see if there's 15 beers in the fridge)

64. -> FAIL !

65. Fixtures setUp()

66. Test1 Starts with empty fridge

67. Fill the fridge with 15 beers

68. Run the test (take 14 beers) tearDown() Drink all the beer left

69. in the fridge setUp()

70. Test2 Starts with empty fridge

71. Fill the fridge with 15 beers

72. Run the test (see if there's 15 beers in the fridge)

73. -> SUCCESS ! tearDown()

74. Fixtures example Running the tests results in : setUp()

75. testAddBeer()

76. tearDown()

77. setUp()

78. teatDrinkBeer()

79. tearDown()

80. setUp()

81. testGetBeerSupply()

82. tearDown() class FridgeTest extends PHPUnit_Framework_TestCase { private $fridge ; protected function setUp() { $this ->fridge = new Fridge(); } protected function tearDown() { $this ->fridge->drinkBeer( $this ->fridge->getBeerSupply() ); } public function testAddBeer() { $this ->assertTrue( $this ->fridge->addBeer( 15 )); } public function testDrinkBeer() { $this ->assertTrue( $this ->fridge->drinkBeer( 15 )); } public function testGetBeerSupply() { $this ->assertType( 'integer' , $this ->fridge->getBeerSupply() ); } }

83. The do's and dont's class User { protected $age ; public function getAge() { return $this ->age; } public function setAge( $newAge ) { if ( $newAge ) { if ( $newAge >= 0 && $newAge <= 150 ) { $this ->age = $newAge ; return true ; } else { return false ; } } else { return false ; } } } class UserTest extends PHPUnit_Framework_TestCase { private $User ; protected function setUp() { $this ->User = new User(); } public function testGetAge() { $this ->assertType( 'integer' , $this ->User->getAge()); } protected static function provideAges() { return array ( array (rand( 0 , 150 )), array (rand( 0 , 150 )), array (rand( 0 , 150 )) ); } /** * @dataProvider provideAges */ public function testSetAge( $age ) { $this ->assertTrue( $this ->User->setAge( $age )); }

84. Problems with this test What about ages < 0 and > 150 ?

85. What about non-integers ?

86. What about empty string ? Null ? protected static function provideInvalidAges() { return array ( array (- 1 ), array ( 151 ), array ( &quot;not an int&quot; ), array ( &quot;&quot; ), array (NULL) ); } /** * @dataProvider provideInvalidAges */ public function testSetAgeInvalid( $age ) { $this ->assertFalse( $this ->User->setAge( $age )); }

87. Good test ? protected static function provideAges() { return array ( array (rand( 0 , 150 )), array (rand( 0 , 150 )), array (rand( 0 , 150 )) ); } /** * @dataProvider provideAges */ public function testSetAge( $age ) { $this ->assertTrue( $this ->User->setAge( $age )); } protected static function provideInvalidAges() { return array ( array (- 1 ), array ( 151 ), array ( &quot;not an int&quot; ), array ( &quot;&quot; ), array (NULL) ); } /** * @dataProvider provideInvalidAges */ public function testSetAgeInvalid( $age ) { $this ->assertFalse( $this ->User->setAge( $age )); }

88. Erratic test results !

89. Bug in the test or the code ? public function setAge( $newAge ) { if ( $newAge ) { if ( $newAge >= 0 && $newAge <= 150 ) { $this ->age = $newAge ; return true ; } else { return false ; } } else { return false ; } } protected static function provideAges() { return array ( array (rand( 0 , 150 )), array (rand( 0 , 150 )), array (rand( 0 , 150 )) ); } /** * @dataProvider provideAges */ public function testSetAge( $age ) { $this ->assertTrue( $this ->User->setAge( $age )); }

90. Bug in the code ! public function setAge( $newAge ) { if (is_int( $newAge )) { if ( $newAge >= 0 && $newAge <= 150 ) { $this ->age = $newAge ; return true ; } else { return false ; } } else { return false ; } } protected static function provideAges() { return array ( array (rand( 0 , 150 )), array (rand( 0 , 150 )), array (rand( 0 , 150 )) ); } /** * @dataProvider provideAges */ public function testSetAge( $age ) { $this ->assertTrue( $this ->User->setAge( $age )); }

91. The code was buggy... what about the test ?

92. Good tests... always test minimum and maximum values

93. always test edge cases

94. So... good test ? We're testing : valid parameters

95. invalid parameters

96. edge cases But : are we actually testing setAge() ?

97. -> We're just checking if setAge() returns true or false ! protected static function provideAges() { return array ( array ( 0 ), array (rand( 1 , 149 )), array (rand( 1 , 149 )), array (rand( 1 , 149 )), array ( 150 ) ); }

98. Good tests... public function testSetAgeActuallySets() { $newAge = mt_rand( 0 , 150 ); $this ->User->setAge( $newAge ); $this ->assertEquals( $newAge , $this ->User->getAge() ); } Good tests don't just cover code... they test the functionality of the code !

99. Testing code – not always easy Some things are hard to test : Private methods

100. Final methods

101. Long methods

102. Singletons / static methods

103. Deep inheritance

104. Too many conditional statements The secret to writing good tests, is to write testable code

105. How NOT to test try { $billingAddress = new Address(&quot;Meir 12&quot;, 2000, &quot;Antwerpen&quot;, &quot;BE&quot;); $officeAddress = new Address(&quot;Groenplaats 50&quot;, 2000, &quot;Antwerpen&quot;, &quot;BE&quot;); $customer = new Customer(402, &quot;Jan&quot;, &quot;De Man&quot;, 32, $billingAddress, $officeAddress); $product = new Product(92, &quot;Speculaas&quot;, 5.95); $invoice = new Invoice($customer); $invoice.addItemQuantity($product, 5); $lineItems = $invoice.getLineitems(); if ($lineItems.size() == 1) { $actualLineItem = $lineItems.get(0); $this->assertEquals($invoice, $actualLineItem.getInvoice()); $this->assertEquals($product, $actualLineItem.getProduct()); $this->assertEquals($quantity, $actualLineItem, getQuantity()); $this->assertEquals(5.95, $actualLineItem.getUnitPrice()); } else { $this->assertTrue(false, 'Invoice should have exactly one line item'); } deleteObject($invoice); deleteObject($product); deleteObject($customer); deleteObject($billingAddress); deleteObject($officeAddress); } catch (Exception $e) { // Whatever }

106. How NOT to test try { $billingAddress = new Address(&quot;Meir 12&quot;, 2000, &quot;Antwerpen&quot;, &quot;BE&quot;); $officeAddress = new Address(&quot;Groenplaats 50&quot;, 2000, &quot;Antwerpen&quot;, &quot;BE&quot;); $customer = new Customer(402, &quot;Jan&quot;, &quot;De Man&quot;, 32, $billingAddress, $officeAddress); $product = new Product(92, &quot;Speculaas&quot;, 5.95); $invoice = new Invoice($customer); $invoice.addItemQuantity($product, 5); $lineItems = $invoice.getLineitems(); $this->assertEquals(1, $lineItems.size()); $actualLineItem = $lineItems.get(0); $this->assertEquals($invoice, $actualLineItem.getInvoice()); $this->assertEquals($product, $actualLineItem.getProduct()); $this->assertEquals($quantity, $actualLineItem, getQuantity()); $this->assertEquals(5.95, $actualLineItem.getUnitPrice()); deleteObject($invoice); deleteObject($product); deleteObject($customer); deleteObject($billingAddress); deleteObject($officeAddress); } catch (Exception $e) { // Whatever }

107. How NOT to test try { $billingAddress = new Address(&quot;Meir 12&quot;, 2000, &quot;Antwerpen&quot;, &quot;BE&quot;); $officeAddress = new Address(&quot;Groenplaats 50&quot;, 2000, &quot;Antwerpen&quot;, &quot;BE&quot;); $customer = new Customer(402, &quot;Jan&quot;, &quot;De Man&quot;, 32, $billingAddress, $officeAddress); $product = new Product(92, &quot;Speculaas&quot;, 5.95); $invoice = new Invoice($customer); $invoice.addItemQuantity($product, 5); $lineItems = $invoice.getLineitems(); $this->assertEquals(1, $lineItems.size()); $actualLineItem = $lineItems.get(0); $this->assertEquals($invoice, $actualLineItem.getInvoice()); $this->assertEquals($product, $actualLineItem.getProduct()); $this->assertEquals($quantity, $actualLineItem, getQuantity()); $this->assertEquals(5.95, $actualLineItem.getUnitPrice()); try { deleteObject($invoice); } catch (Exception $e) { // Whatever } try { deleteObject($product); } catch (Exception $e) { // Whatever } try { deleteObject($customer); } catch (Exception $e) { // Whatever } try { deleteObject($billingAddress); } catch (Exception $e) { // Whatever } try { deleteObject($officeAddress); } catch (Exception $e) { // Whatever } } catch (Exception $e) { // Whatever }

108. Make a testObject array protected $testObjects; public function testInvoice() { $billingAddress = new Address(&quot;Meir 12&quot;, 2000, &quot;Antwerpen&quot;, &quot;BE&quot;); $this->addTestObject($billingAddress); $officeAddress = new Address(&quot;Groenplaats 50&quot;, 2000, &quot;Antwerpen&quot;, &quot;BE&quot;); $this->addTestObject($officeAddress); $customer = new Customer(402, &quot;Jan&quot;, &quot;De Man&quot;, 32, $billingAddress, $officeAddress); $this->addTestObject($customer); $product = new Product(92, &quot;Speculaas&quot;, 5.95); $this->addTestObject($product); $invoice = new Invoice($customer); $this->addTestObject($invoice); $invoice.addItemQuantity($product, 5); $lineItems = $invoice.getLineitems(); $this->assertEquals(1, $lineItems.size()); $actualLineItem = $lineItems.get(0); $this->assertEquals($invoice, $actualLineItem.getInvoice()); $this->assertEquals($product, $actualLineItem.getProduct()); $this->assertEquals($quantity, $actualLineItem, getQuantity()); $this->assertEquals(5.95, $actualLineItem.getUnitPrice()); } public function tearDown() { $this->deleteTestObjects(); } Note : this is a design decision from the very start of your project, since all objects need the same method for deletion

109. Replace the unneeded data protected $testObjects; public function testInvoice() { $billingAddress = new TestAddress(); $this->addTestObject($billingAddress); $officeAddress = new TestAddress(); $this->addTestObject($officeAddress); $customer = new TestCustomer($billingAddress, $officeAddress); $this->addTestObject($customer); $product = new Product(92, &quot;Speculaas&quot;, 5.95); $this->addTestObject($product); $invoice = new Invoice($customer); $this->addTestObject($invoice); $invoice.addItemQuantity($product, 5); $lineItems = $invoice.getLineitems(); $this->assertEquals(1, $lineItems.size()); $actualLineItem = $lineItems.get(0); $this->assertEquals($invoice, $actualLineItem.getInvoice()); $this->assertEquals($product, $actualLineItem.getProduct()); $this->assertEquals($quantity, $actualLineItem, getQuantity()); $this->assertEquals(5.95, $actualLineItem.getUnitPrice()); } public function tearDown() { $this->deleteTestObjects(); }

110. Instantiating objects (1/3) Looks like a standard test-class relationship, with invoice being a 'leaf' class

111. Until you look at the Invoice class

112. Instantiating objects (2/3) Create a seam which separates your class from other classes

113. Instantiating objects (3/3) Don't do 'new Customer' in Invoice, instead do it in the test and pass it as a parameter

114. Advantages : Objects can be tested separately

115. Hard-to-test classes can be mocked (replaced by a fake class) Important : you have to keep this in mind when writing your code !

116. Testable code Good object orientation

117. Dependency injection

118. Uses TDD

119. Test-Driven Development Reverse programming logic : Write the test

120. then

121. Write the code If code is too complex -> hard to test

122. Write the test first -> code will do what the test dictates

123. It's a habit...

124. and it's addicting !

125. Random thoughts... # lines test ≈ # lines code Why ? Because you need to test invalid cases, edge cases, etc. You can add your own assertions

126. Multi-developer projects : If you launch tests simultaneously -> unexpected (and unrepeatable) results -> agree on a token

127. Agree on 'punishment' for who breaks the build (buy a beer, go get coffee, …) -> makes people test locally before committing code

128. We typed the test... Now let's test the type !

129. What is it ? A PHPUnit addon / patch

130. Allows type validation during unit testing

131. Time it took to build : a few days

132. Time it takes for developers to use : none Just add --check-param-types to your PHPUnit call

133. See the magic happen

134. How it works It analyzes the docblock

135. When the method is called from our test, it compares the type of each parameter with the type in the docblock :

136. The result : /** * Cat constructor * @param string $name The name of the cat * @param int $lives The number of lives this cat has left */ PHPUnit 3.5 by Sebastian Bergmann. FF... Time: 1 second, Memory: 3.25Mb There were 2 failures: 1) CatTest::test__constructWithNegativeLives Invalid type calling Cat->__construct : parameter 1 ($name) should be of type string but got bool instead in /home/dev/paramtest/tests/CatTest.php 2) CatTest::test__constructWithNegativeLives Invalid type calling Cat->__construct : parameter 2 ($lives) should be of type int but got string instead in /home/dev/paramtest/tests/CatTest.php FAILURES! Tests: 5, Assertions: 8, Failures: 2. $cat = new Cat(true, &quot;9&quot;);

137. Why it's useful PHP's dynamic typing is great, but it can be a pain !

138. If you write a library : You want to be sure people pass the right parameter types

139. You don't want to do is_int(), is_bool(), ... all the time If you modify your function's parameters : If you forget to modify the callee : warning will be shown

140. If you forget to update your docblock : warning will be shown Parameter type validation was designed to help your data be consistent and of the type expected during design !

141. (and it forces you to keep the docblock updated,

142. which is good for API documentation quality !)

143. How to install and run Go to http://github.com/wimg/phpunit

144. Click on 'Download Source'

145. Run it :

146. > php <path-to-phpunit.php> --check-param-types <your-test.php>

147. Be amazed at how many type issues you have ;-)

148. Warning Work in progress

149. Slows down unit tests by factor of 2.5

150. MySQL = trouble (but we're looking into it)

151. Let's refresh Tests should always pass or fail, but never behave erratically -> Consistency is the key to code quality

152. -> Consistency gives the developer confidence in testing Always test valid and invalid cases

153. Always test the edge cases

154. Don't rely on completion of other tests -> Use fixtures Use docblocks

155. Test your types for consistency

156. -> Unit tests take a developer from :

157. This code should work

158. to

159. I can prove it works

160. Cu.be Solutions Founded in 2010

161. Spinoff of FirstLink Networks (founded in 2000)

162. High-quality open source solutions

163. Centered around PHP

164. Contribute to open source projects

165. (ZF, Xdebug, PHPUnit, OpenX, ...)

166. We're hiring !

167. -> http://cu.be/jobs

168. -> info@cu.be

169. Questions ?

170. Thanks !

171. Contact Web http://joind.in/talk/view/xxx http://cu.be

172. http://techblog.wimgodden.be Slides http://www.slideshare.net/wimg

173. Twitter @wimgtr

174. E-mail [email_address]