Unit Testing with JUnit

This class provides a brief Introduction to (Unit) Testing Automation using JUnit 4.x

Transcript

1. UNIT TESTING WITH JUNIT Software Engineering Class Valerio Maggio, Ph.D. valerio.maggio@unina.it Prof. Adriano Peron Dec, 6th 2013
2. BRIEF INTRO TO THE CLASS It’s about Unit Testing It’s about JUnit
3. BRIEF INTRO TO THE CLASS It’s about Unit Testing It’s about JUnit + It’s about.. ? Make a guess….
4. BRIEF INTRO TO THE CLASS It’s about Unit Testing It’s about JUnit + It’s about 
 Unit Testing with JUnit You say?!
5. DISCLAIMER • At the end of the class you (should)... 1. ..have learnt something more about unit testing; 2. ..have learnt what is JUnit, how to use it and when; 3. ..have realized how much important are testing activities! This is not a Tutorial Class
6. JUNIT PRELIMINARIES • Q: How many “types” of testing do you know?
7. JUNIT PRELIMINARIES • Q: How many “types” of testing do you know? • A: System Testing, Integration Testing, Unit Testing....

8. JUNIT PRELIMINARIES • Q: How many “types” of testing do you know? • A: System Testing, Integration Testing, Unit Testing....
 • Q: How many “testing techniques” do you know?
9. JUNIT PRELIMINARIES • Q: How many “types” of testing do you know? • A: System Testing, Integration Testing, Unit Testing....
 • Q: How many “testing techniques” do you know? • A: Black Box and White Box Testing
 
 Which is the difference?
10. JUNIT PRELIMINARIES • Q: How many “types” of testing do you know? • A: System Testing, Integration Testing, Unit Testing....
 • Q: How many “testing techniques” do you know? • A: Black Box and White Box Testing
 
 Which is the difference? • Q: What type and technique do you think JUnit covers?
11. JUNIT WORDS CLOUD a.k.a. some random words (almost) related to JUnit Unit Testing Testing
12. JUNIT WORDS CLOUD a.k.a. some random words (almost) related to JUnit Unit Testing Java Testing
13. JUNIT WORDS CLOUD a.k.a. some random words (almost) related to JUnit Unit Testing Java Testing Testing framework
14. JUNIT WORDS CLOUD a.k.a. some random words (almost) related to JUnit Unit Testing Java Testing Testing framework xUnit
15. JUNIT WORDS CLOUD a.k.a. some random words (almost) related to JUnit Unit Testing Java Testing Black Box Testing Testing framework xUnit
16. JUNIT WORDS CLOUD a.k.a. some random words (almost) related to JUnit Unit Testing Java Testing Black Box Testing Testing framework xUnit Test Suite
17. JUNIT WORDS CLOUD a.k.a. some random words (almost) related to JUnit Unit Testing Java Testing Black Box Testing Testing framework xUnit Test Suite Test Fixtures
18. JUNIT WORDS CLOUD a.k.a. some random words (almost) related to JUnit Unit Testing Java Testing Black Box Testing Testing framework xUnit Test Suite Test Fixtures Test Runners
19. JUNIT WORDS CLOUD a.k.a. some random words (almost) related to JUnit Unit Testing Java Testing Black Box Testing Testing framework xUnit Test Suite Test Fixtures Test Runners Simple Test Program
20. JUNIT WORDS CLOUD a.k.a. some random words (almost) related to JUnit Unit Testing Java Testing Black Box Testing Testing framework xUnit Test Suite Test Fixtures Test Runners Simple Test Program Testing Automation
21. THE IMPORTANCE OF TESTING • During development, the first thing we do is run our own program! • This is (sometimes) called Acceptance Testing Code Compile Run Test/Debug
22. JUnit is a simple framework to write repeatable tests. 
 It is an instance of the xUnit architecture for 
 unit testing frameworks. JUnit: a.k.a. A programmer-oriented testing framework for Java
23. JUnit is a simple framework to write repeatable tests. 
 It is an instance of the xUnit architecture for 
 unit testing frameworks. JUnit: a.k.a. A programmer-oriented testing framework for Java
24. UNIT TEST Unit Test: A unit test examines the behaviour of a distinct unit of work.
25. UNIT TEST Unit Test: A unit test examines the behaviour of a distinct unit of work. The “distinct unit of work” is often (but not always) a single class.
26. UNIT TEST Unit Test: A unit test examines the behaviour of a distinct unit of work. The “distinct unit of work” is often (but not always) a single class. Unit tests run fast! (If they don’t, they’re not Unit tests)
27. UNIT TEST Unit Test: A unit test examines the behaviour of a distinct unit of work. The “distinct unit of work” is often (but not always) a single class. Unit tests run fast! (If they don’t, they’re not Unit tests) Unit tests run in isolation! (no dependencies)
28. Why UNIT TESTING • Unit tests ensure that code works as intended.
29. Why UNIT TESTING • Unit tests ensure that code works as intended. • (Also) very helpful to ensure that the code still works as intended in case you need to modify code ! • e.g., fixing a bug or extending functionality.
30. Why UNIT TESTING • Unit tests ensure that code works as intended. • (Also) very helpful to ensure that the code still works as intended in case you need to modify code ! • e.g., fixing a bug or extending functionality. • Test Coverage: the percentage of code tested by unit tests! • Test coverage should be as high as possible. Why?
31. Why UNIT TESTING • Unit tests ensure that code works as intended. • (Also) very helpful to ensure that the code still works as intended in case you need to modify code ! • e.g., fixing a bug or extending functionality. • Test Coverage: the percentage of code tested by unit tests! • Test coverage should be as high as possible. Why? • Test Fixture: a fixed state of the software under test used as a baseline for running tests
32. Why UNIT TESTING • Unit tests ensure that code works as intended. • (Also) very helpful to ensure that the code still works as intended in case you need to modify code ! • e.g., fixing a bug or extending functionality. • Test Coverage: the percentage of code tested by unit tests! • Test coverage should be as high as possible. Why? • Test Fixture: a fixed state of the software under test used as a baseline for running tests
33. Other TYPES OF TESTING • Integration Tests: test the behaviour of a component;
34. Other TYPES OF TESTING • Integration Tests: test the behaviour of a component; • (or) the integration between a set of components.
35. Other TYPES OF TESTING • Integration Tests: test the behaviour of a component; • (or) the integration between a set of components. • (Sometimes) Called Functional Tests
36. Other TYPES OF TESTING • Integration Tests: test the behaviour of a component; • (or) the integration between a set of components. • (Sometimes) Called Functional Tests • These kind of tests would resemble a expected user interaction with the application.
37. Other TYPES OF TESTING • Integration Tests: test the behaviour of a component; • (or) the integration between a set of components. • (Sometimes) Called Functional Tests • These kind of tests would resemble a expected user interaction with the application. • Performance Tests: measure performance of software components in a repeatable way.
38. JUnit is a simple framework to write repeatable tests. 
 It is an instance of the xUnit architecture for 
 unit testing frameworks. JUnit: a.k.a. A programmer-oriented testing framework for Java
39. JUnit is a simple framework to write repeatable tests. 
 It is an instance of the xUnit architecture for 
 unit testing frameworks. JUnit: a.k.a. A programmer-oriented testing framework for Java
40. FRAMEWORK A framework is a semi-complete application that provides a reusable, common structure that can be shared between applications.
41. FRAMEWORK A framework is a semi-complete application that provides a reusable, common structure that can be shared between applications. Developers incorporate the framework in their own application and extend it to meet their specific needs.
42. FRAMEWORK (in other words) • A framework provides a working infrastructure to be used for a specific task • i.e., the same task the framework was designed for. • Developers integrate the framework by:
43. FRAMEWORK (in other words) • A framework provides a working infrastructure to be used for a specific task • i.e., the same task the framework was designed for. • Developers integrate the framework by: • adopting the design rules of the framework (in design)
44. FRAMEWORK (in other words) • A framework provides a working infrastructure to be used for a specific task • i.e., the same task the framework was designed for. • Developers integrate the framework by: • adopting the design rules of the framework (in design) • Importing, subclassing, …extending framework functionalities (in code)
45. FRAMEWORK (in other words) • A framework provides a working infrastructure to be used for a specific task • i.e., the same task the framework was designed for. • Developers integrate the framework by: • adopting the design rules of the framework (in design) • Importing, subclassing, …extending framework functionalities (in code) • Btw, they avoid writing boilerplate code
46. WHY A FRAMEWORK IS NEEDED? Let’s do a very dummy example... Q: How would you test this method?
47. VERY SIMPLE TESTING STRATEGY
48. VERY SIMPLE TESTING STRATEGY Q: How would you improve it?
49. IMPROVED (Naive) SOLUTION
50. LESSON LEARNED Objective Test + Repeatable Test = Simple Test Program
51. LESSON LEARNED Objective Test + Repeatable Test = Simple Test Program Beware: 
 Previous Code showed a 
 naive way of testing 
 (a.k.a. the wrong one)
52. LESSON LEARNED Objective Test + Repeatable Test = Simple Test Program Beware: 
 Previous Code showed a 
 naive way of testing 
 (a.k.a. the wrong one) That was not JUnit!!
53. JUNIT'S Way
54. JUNIT'S Way Q: Do you already know 
 these constructs (@) 
 (in Java)?
55. JUNIT (main) FEATURES • JUnit features include:
56. JUNIT (main) FEATURES • JUnit features include: • Assertions for testing expected results
57. JUNIT (main) FEATURES • JUnit features include: • Assertions for testing expected results • Test fixtures for sharing common test data
58. JUNIT (main) FEATURES • JUnit features include: • Assertions for testing expected results • Test fixtures for sharing common test data • Test runners for running tests
59. TESTCALCULATOR JUNIT 4
60. TESTCALCULATOR JUNIT 4 TestAnnotation
61. TESTCALCULATOR JUNIT 4 TestAnnotation JUnit Assert
62. THE TEST FAILS! (as expected)
63. THE TEST FAILS! (as expected) IDE: IntelliJ IDEA 12 CE http://www.jetbrains.com/idea/
64. JUNIT 4.X DESIGN • Main features inspired from other Java Unit Testing Frameworks! • TestNG • Test Method Annotations! • Requires Java5+! • Main Method Annotations! • @Before, @After • @Test, @Ignore • @SuiteClasses, @RunWith
65. JUNIT TEST ANNOTATIONS • @Test public void testMethodName() • Annotation @Test identifies that testMethodName is a test method.
66. JUNIT TEST ANNOTATIONS • @Test public void testMethodName() • Annotation @Test identifies that testMethodName is a test method. • @Before public void beforeMethodName() • beforeMethodName() will be executed before each test.! • This method can prepare the test environment! • e.g., read input data, initialise the class, …! • Traditionally named setUp() (for “historical” reasons)
67. JUNIT TEST ANNOTATIONS • @Test public void testMethodName() • Annotation @Test identifies that testMethodName is a test method. • @Before public void beforeMethodName() • beforeMethodName() will be executed before each test.! • This method can prepare the test environment! • e.g., read input data, initialise the class, …! • Traditionally named setUp() (for “historical” reasons) • @After public void afterMethodName() • afterMethodName() will be executed after each test.! • Traditionally named tearDown() (for “historical” reasons)
68. JUNIT ANNOTATIONS (2) • @Ignore • Will ignore the test method! • E.g. Useful if the underlying code has been changed and the test has not yet been adapted.

69. JUNIT ANNOTATIONS (2) • @Ignore • Will ignore the test method! • E.g. Useful if the underlying code has been changed and the test has not yet been adapted.
 • @Test(expected=Exception.class) • Tests if the method throws the named exception.

70. JUNIT ANNOTATIONS (2) • @Ignore • Will ignore the test method! • E.g. Useful if the underlying code has been changed and the test has not yet been adapted.
 • @Test(expected=Exception.class) • Tests if the method throws the named exception.
 • @Test(timeout=100) • Fails if the method takes longer than 100 milliseconds.
71. java.lang.Annotation AT GLANCE • Meta Data Tagging (package java.lang.annotation)! • Target (java.lang.annotation.ElementType) • Specify to which element the annotation is applied! • FIELD • METHOD • CLASS • Retention • Specify how long annotation should be available
72. @TEST ANNOTATION
73. TEST FIXTURES SetUp testXXX tearDown fixture: The set of common resources or data that you need to run one or more tests. @Before @After @Test
74. JUNIT ASSERT STATEMENTS • assertNotNull([message], object) • Test passes if Object is not null.
75. JUNIT ASSERT STATEMENTS • assertNotNull([message], object) • Test passes if Object is not null. • assertNull([message], object) • Test passes if Object is null.
76. JUNIT ASSERT STATEMENTS • assertNotNull([message], object) • Test passes if Object is not null. • assertNull([message], object) • Test passes if Object is null. • assertEquals([message],expected, actual) • Asserts equality of two values
77. JUNIT ASSERT STATEMENTS • assertNotNull([message], object) • Test passes if Object is not null. • assertNull([message], object) • Test passes if Object is null. • assertEquals([message],expected, actual) • Asserts equality of two values • assertTrue(true|false) • Test passes if condition is True
78. JUNIT ASSERT STATEMENTS • assertNotNull([message], object) • Test passes if Object is not null. • assertNull([message], object) • Test passes if Object is null. • assertEquals([message],expected, actual) • Asserts equality of two values • assertTrue(true|false) • Test passes if condition is True • assertNotSame([message], expected, actual) • Test passes if the two Objects are not the same Object
79. JUNIT ASSERT STATEMENTS • assertNotNull([message], object) • Test passes if Object is not null. • assertNull([message], object) • Test passes if Object is null. • assertEquals([message],expected, actual) • Asserts equality of two values • assertTrue(true|false) • Test passes if condition is True • assertNotSame([message], expected, actual) • Test passes if the two Objects are not the same Object • assertSame([message], expected, actual) • Test passes if the two Objects are the same Object
80. TESTING EXCEPTION HANDLING try-catch trick!
81. TESTING THE EXCEPTION HANDLING
    THE NEW WAY! Use the expected parameter of @Test annotation
82. A look at the past: JUNIT 3.X • All the Test classes must extend junit.framework.TestCase! • Functionalities by inheritance
83. A look at the past: JUNIT 3.X • All the Test classes must extend junit.framework.TestCase! • Functionalities by inheritance • All the test method's names must start with the “keyword”
 test in order to be executed by the framework! • testSomething() • testSomethingElse()
84. XUNIT DESIGN JUnit 3.x design was compliant with xUnit framework guidelines <<interface>> Test TestCase TestSuite MyTestCase * - JUnit! - CppUnit! - PyUnit! - NUnit! - XMLUnit! - PHPUnit! - RUnit! - SUnit! - .....
85. (Vintage !-) 
 JUNIT TEST EXAMPLE
86. GET THE CODE github.com/junit-team/junit
87. • Requirements:! • Input numbers cannot have more than 5 digits;! • The calculator can remember a given (unique) number;! • Only non-negative numbers are allowed.! • In case of negative numbers, an exception is thrown! Calculator + add (double augend, double addend): double + subtract (double minuend, double subtrahend): double + multiply (double multiplicand, double multiplier): double + divide (double dividend, double divisor): double + addToMemory(double number): void + recallNumber(): double - memory: double + MAX_DIGITS_LEN: int = 5 <<final>> <<static>>
88. Some REFERENCES vogella.com/articles/JUnit/article.html github.com/junit-team/junit/wiki
89. Some REFERENCES Unit Test Frameworks! Tools for High-Quality Software Development! Paul Hamill, O’Reilly Media 2004 JUnit in Action 2nd Ed.
 Massol et al. , Manning Pubs 2009
90. CONTACTS MAIL: valerio.maggio@unina.it http://wpage.unina.it/valerio.maggio
91. THANK YOU FOR YOUR KIND ATTENTION !-)