MI-RUB Testing Lecture 10

Transcription

1 MI-RUB Testing Lecture 10 Pavel Strnad Dept. of Computer Science, FEE CTU Prague, Karlovo nám. 13, Praha, Czech Republic MI-RUB, WS 2011/12 Evropský sociální fond Praha & EU: Investujeme do vaší budoucnosti Pavel Strnad (Czech Technical University in Prague) MI-RUB Testing Lecture 10 MI-RUB, / 15

2 Contents 1 Unit Testing 2 The Testing Framework 3 Assertions 4 Structuring Tests 5 Literature Pavel Strnad (Czech Technical University in Prague) MI-RUB Testing Lecture 10 MI-RUB, / 15

3 Unit Testing Unit Testing Focuses on small chunks (units) of code, typically individual methods or lines within methods. Layers principle - If there is a bug on a lower layer then it will surely propagate to a higher level! So, We need unit testing. It goes hand in hand with Ruby. Pavel Strnad (Czech Technical University in Prague) MI-RUB Testing Lecture 10 MI-RUB, / 15

4 Test Driven Development TDD Write a test before implementation. You will write a better code! Pavel Strnad (Czech Technical University in Prague) MI-RUB Testing Lecture 10 MI-RUB, / 15

5 Testing Example Roman Numbers Implementation class Roman MAX_ROMAN = 4999 def i n i t i a l i z e ( value = value FACTORS = [ [ "m", 1000], [ "cm", 900], [ " d ", 500], [ " cd ", ],... ] def to_s value roman = " " for code, f a c t o r in FACTORS count, value = value. divmod ( f a c t o r ) roman << code unless count. zero? roman Pavel Strnad (Czech Technical University in Prague) MI-RUB Testing Lecture 10 MI-RUB, / 15

6 Roman Numbers Naive Test r e q u i r e roman r = Roman. new ( 1 ) f a i l " i expected " unless r. to_s == " i " r = Roman. new ( 9 ) f a i l " i x expected " unless r. to_s == " i x " This will be unmanageable for bigger projects. Pavel Strnad (Czech Technical University in Prague) MI-RUB Testing Lecture 10 MI-RUB, / 15

7 The Testing Framework The Testing Framework Properties The Ruby testing framework is basically three facilities wrapped into a neat package: It gives you a way of expressing individual tests. It provides a framework for structuring the tests. It gives you flexible ways of invoking the tests. Ruby provides two main frameworks Test::Unit and Minitest::Unit (from 1.9). Pavel Strnad (Czech Technical University in Prague) MI-RUB Testing Lecture 10 MI-RUB, / 15

8 Assertions == Expected Results Assertions Rather than have you write series of individual if statements in your tests, the testing framework provides a set of assertions that achieve the same thing. Pavel Strnad (Czech Technical University in Prague) MI-RUB Testing Lecture 10 MI-RUB, / 15

9 Assertions Roman Numbers Unit Test r e q u i r e roman r e q u i r e t e s t / u n i t class TestRoman < Test : : Unit : : TestCase def t e s t _ s i m p l e assert_equal ( " i ", Roman. new ( 1 ). to_s ) assert_equal ( " i i ", Roman. new ( 2 ). to_s ) assert_equal ( " i i i ", Roman. new ( 3 ). to_s ) assert_equal ( " i v ", Roman. new ( 4 ). to_s ) assert_equal ( " i x ", Roman. new ( 9 ). to_s ) Pavel Strnad (Czech Technical University in Prague) MI-RUB Testing Lecture 10 MI-RUB, / 15

10 Roman Numbers Exercise Exercise 1 Fix the implementation of Roman Numbers to pass the test test_simple. Pavel Strnad (Czech Technical University in Prague) MI-RUB Testing Lecture 10 MI-RUB, / 15

11 Roman Numbers Test Improved Roman Numbers Test Improved The Test::Unit framework uses reflection to run methods starting with a word test. r e q u i r e roman r e q u i r e t e s t / u n i t class TestRoman < Test : : Unit : : TestCase NUMBERS = [ [ 1, " i " ], [ 2, " i i " ], [ 3, " i i i " ], [ 4, " i v " ], [ 5, " v " ], [ 9, " i x " ] ] def t e s t _ s i m p l e NUMBERS. each do arabic, roman r = Roman. new( a rabic ) assert_equal ( roman, r. to_s ) Pavel Strnad (Czech Technical University in Prague) MI-RUB Testing Lecture 10 MI-RUB, / 15

12 Asserts a s s e r t _ r a i s e s ( RuntimeError ) { Roman. new ( 0 ) } r e f u t e _ n i l ( user, " User with ID=1 should e x i s t " ) assert_equal ( roman, r. to_s ) refute_equal ( roman, r. to_s ) Pavel Strnad (Czech Technical University in Prague) MI-RUB Testing Lecture 10 MI-RUB, / 15

13 Structuring Tests Unit tests are groupped into high-level groupings called test cases. The test cases generally contain all the tests relating to a particular facility or feature. The classes that represent test cases must be subclasses of Test::Unit::TestCase. Pavel Strnad (Czech Technical University in Prague) MI-RUB Testing Lecture 10 MI-RUB, / 15

14 Test methods setup and teardown If we have a common code which should be run in the beginning and in the of each test method (e.g. database connection, initialization of resources) we can extract it to setup and teardown methods. These methods act like brackets around each test method. Pavel Strnad (Czech Technical University in Prague) MI-RUB Testing Lecture 10 MI-RUB, / 15

15 All examples are from Pavel Strnad (Czech Technical University in Prague) MI-RUB Testing Lecture 10 MI-RUB, / 15