Unit Tes2ng Ac2vity. SWEN-261 Introduc2on to So3ware Engineering. Department of So3ware Engineering Rochester Ins2tute of Technology

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1 Unit Tes2ng Ac2vity SWEN-261 Introduc2on to So3ware Engineering Department of So3ware Engineering Rochester Ins2tute of Technology

2 Your activity for the Unit Testing lesson is to build tests for existing Project components. These slides direct you through the process of creating unit tests for your project. ü Activity actions are highlighted in green with a checkmark bullet. But first, these slides provide technical details: 1. How to organize test classes using Maven 2. How to run tests using Maven 3. How to structure a typical test class 4. How to use JUnit assertion functions 5. How to use package-private constants in test code 6. How to use Mockito mock objects using Dependency Injection 2

3 Maven provides a convenient structure for organizing unit test code. Put your test classes in a separate source path. The goal is to keep the test source code separate from the production source code. Using Maven that is usually src/test/java. ü Create this directory if it doesn't already exist. ü (Optional) Link your IDE to this source path. Most IDEs provide wizards for creating unit tests. Make sure the IDE stores the test classes in the proper source path. The unit test code examples in these slides are from the Guessing Game. See the Unit Testing topic page for a link to the ZIP file. 3

4 Maven will run tests during builds and there is also the test target. [~/workspace/guessing-game] mvn clean test [INFO] Scanning for projects... // SKIPPING SOME Maven OUTPUT T E S T S Running com.example.appl.gamecentertest Tests run: 6, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: sec Running com.example.model.guessgametest Tests run: 9, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: sec Running com.example.ui.getgameroutetest Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: sec Running com.example.ui.gethomeroutetest Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: sec Running com.example.ui.postguessroutetest Tests run: 5, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: sec Results : Tests run: 24, Failures: 0, Errors: 0, Skipped: 0 [INFO] [INFO] BUILD SUCCESS [INFO]

5 The structure of a unit test class. Name the test class after the component under test (CuT) in the same package. So if CuT is com.example.model.myentity Then test class is: com.example.model.myentitytest Doing so gives the test code package-private access to CuT class. Annotate each test method with. Use annotated method to setup common test scenario; an example comes later. Use annotated method to clean up. 5

6 Recall the checklist of types of unit tests. Business logic Tests for each path through a method Happy path as well as failure paths Constructors and accessors Defensive programming checks Validation of method arguments w NullPointerException w IllegalArgumentException Validation of component state w IllegalStateException The equals and hashcode methods, as needed Exception handling 6

7 Here's an example unit test suite for the GuessGame class. package com.example.model; import static org.junit.assert.*; import org.junit.test; public class GuessGameTest { public void ctor_noarg() {... public void ctor_witharg() {... (expected = IllegalArgumentException.class) public void ctor_toobig() {... (expected = IllegalArgumentException.class) public void ctor_toosmall() {... public void isvalidguess() {... public void testgameplay_win_first_try() {... public void testgameplay_win_second_try() {... public void testgameplay_win_last_try() {... public void testgameplay_loose() {... 7 Import JUnit assertion functions. Test constructors. Test defensive programming checks. Test business logic.

8 Here's an example test method for the GuessGame class. import static org.junit.assert.*; import org.junit.test; public class GuessGameTest { public void testgameplay_win_first_try() { // Setup test scenario: game start (also Invoke test) final GuessGame CuT = new GuessGame(NUMBER); // Analyze results asserttrue(cut.isgamebeginning()); asserttrue(cut.hasmoreguesses()); assertequals(3, CuT.guessesLeft()); // Invoke test: first guess, correct asserttrue(cut.makeguess(number)); // Analyze results assertfalse(cut.isgamebeginning()); asserttrue(cut.hasmoreguesses()); assertequals(2, CuT.guessesLeft()); 8

9 Here's an example of how to test an expected exception. 9 Use the annotation expected attribute: public class GuessGameTest { private static final int TOO_BIG = 11; (expected = IllegalArgumentException.class) public void ctor_toobig() { new GuessGame(TOO_BIG); Roughly the same as: public class GuessGameTest { private static final int TOO_BIG = 11; public void ctor_toobig() { try { new GuessGame(TOO_BIG); fail("ctor should fail."); catch (IllegalArgumentException e) { // success, do nothing

10 JUnit has many built-in assertions you can use. 10 Test truth-hood asserttrue([message,] condition) assertfalse([message,] condition) Test values or objects for equality assertequals([message,] expected, actual) assertnotequals([message,] expected, actual) Test objects for identity (obj1 == obj2) assertsame([message,] expected, actual) assertnotsame([message,] expected, actual) Test null-hood assertnull([message,] object) assertnotnull([message,] object) Automatic failure: fail(message)

11 Recall the coding tip recommended. Idioms for testable code: Make message strings (and other values) constants Make these members package-private (or public) Example: public class GameCenter { final static String NO_GAMES_MESSAGE = "No games have been played so far."; final static String ONE_GAME_MESSAGE = "One game has been played so far."; final static String GAMES_PLAYED_FORMAT = "There have been %d games played."; public synchronized String getgamestatsmessage() { if (totalgames > 1) { return String.format(GAMES_PLAYED_FORMAT, totalgames); else if (totalgames == 1) { return ONE_GAME_MESSAGE; else { return NO_GAMES_MESSAGE; 11

12 Here's how the test code would use these members. /** * Test the Game stats message over multiple games played. */ public void play_several_games() { // Setup the test scenario: no games play yet final GameCenter CuT = new GameCenter(); // * Analyze the results assertequals(gamecenter.no_games_message, CuT.getGameStatsMessage()); // * Create first game CuT.end(makeSession()); // * Analyze the results of first game assertequals(gamecenter.one_game_message, CuT.getGameStatsMessage()); // * Create second game CuT.end(makeSession()); // * Analyze the results of second game assertequals(string.format(gamecenter.games_played_format, 2), CuT.getGameStatsMessage()); 12 // * Create third game CuT.end(makeSession()); // * Analyze the results of third game assertequals(string.format(gamecenter.games_played_format, 3), CuT.getGameStatsMessage());

For example, the PostGuessRoute controller also needs access to the GameCenter Application component.

13 Now let's consider writing tests for more complex components; one's with dependencies. UI Controllers in Spark need to access Spark's HTTP request, session and response objects. For example, the PostGuessRoute controller also needs access to the GameCenter Application component. So this component's seam looks like this: The GameCenter and GuessGame are thoroughly tested so are friendly. 13 Use mock objects for Spark dependencies.

14 To review: this is what dependency injection looks like in the component under test. public class PostGuessRoute implements TemplateViewRoute { private final GameCenter gamecenter; 14 /** * The constructor for the {@code POST /guess route handler. * gamecenter * The {@link GameCenter for the application. * NullPointerException * when the {@code gamecenter parameter is null */ PostGuessRoute(final GameCenter gamecenter) { // validation Objects.requireNonNull(gameCenter, "gamecenter must not be null"); // this.gamecenter = gamecenter; This JDK method performs a null This class is instantiated by check and throws an NPE if violated. the WebServer component, which configures Spark.

15 The GameCenter class has been thoroughly tested so it is a friendly dependency. import static org.junit.assert.*; import static org.mockito.mockito.*; public class PostGuessRouteTest { Import Mockito functions. private static final int NUMBER = 7; private static final String WRONG_GUESS = "3"; private static final String NOT_A_NUMBER = "asdf"; private static final String INVALID_GUESS = "47"; /** * The component-under-test (CuT). * * <p> * This is a state-less component so we only need one. */ private PostGuessRoute CuT = new PostGuessRoute(new GameCenter()); The friendly GameCenter is injected into the CuT object using constructor-injection. 15

16 We'll use mocks for the Spark components and create these new for each test run. 16 public class PostGuessRouteTest { // attributes holding mock objects private Request request; private Session session; private Response response; /** * Setup new mock objects for each test. public void setup() { request = mock(request.class); session = mock(session.class); when(request.session()).thenreturn(session); final GuessGame game = new GuessGame(NUMBER); when(session.attribute(eq(gamecenter.game_id))).thenreturn(game); response = mock(response.class); Use the Mockito mock function to create a mock object, eg, for a Spark Request object. Use the Mockito when and thenreturn APIs to simulate a method call on a mock object.

17 Configure the mock object to direct the scenario of the test. For this specific test case, we also need to public class PostGuessRouteTest { specify the Request 'guess' query parameter. public void bad_guess_1() { // Setup the test scenario: The user's guess is not valid number. when(request.queryparams(eq(guesspostroute.guess_param))).thenreturn(not_a_number); // Invoke the test final ModelAndView result = CuT.handle(request, response); 17 // Analyze the results: // * result is non-null assertnotnull(result); // * model is a non-null Map final Object model = result.getmodel(); assertnotnull(model); asserttrue(model instanceof Map); // * model contains all necessary View-Model final Map<String, Object> vm = (Map<String, Object>) model; assertequals(gamegetroute.title, vm.get(homegetroute.title_attr)); assertequals(boolean.false, vm.get(homegetroute.new_session_attr)); assertequals(guesspostroute.error_type, vm.get(guesspostroute.message_type_attr)); assertequals(guesspostroute.makebadargmessage(not_a_number), vm.get(guesspostroute.message_attr)); // * test view name assertequals(gamegetroute.view_name, result.getviewname());

18 Mockito has a rich API for setting scenarios and for inspecting test activity. Arranging scenarios: when(mock.method(args)).thenreturn(value) when(mock.method(args)).thenthrow(new XyzExc()) when(mock.method(args)).thenanswer(lambda) Inspecting activity within the CuT method: verify(mock).method(args) verify(mock, times(1)).method(args) Other verification modes: w times(n), atleast(n), atmost(n) & never() Specifying arguments: An actual value or object: eq(value) or eq(object) Any value (anyint(), etc); any() for any Object Many more types of Matchers 18

19 Your exercise is to build unit tests for two classes in your Project. ü Each team member picks two classes in your project and builds unit tests for them. Each team member will pick different classes to test. If you need to refactor the code to make the component more testable then do so. ü Create the test class in the appropriate package in the test source path. ü Create a reasonable set of test cases. At least three test cases for each CuT. Focus on the business logic methods (eg, the handle method for UI Controllers). 19

20 Your exercise is to build unit tests for two classes in your Project. ü Upload the two unit test source files to the Unit Testing Dropbox in MyCourses. ü Add this to your Definition of Done checklist in Story template card in Trello: Create unit tests. 20

Unit Testing Activity

Unit Testing Activity SWEN-261 Introduction to Software Engineering Department of Software Engineering Rochester Institute of Technology Your activity for the Unit Testing lesson is to build tests for