The goal of this document is to provide comprehensive reference documentation for programmers writing tests, extension authors, and engine authors as well as build tool and IDE vendors. Unlike previous versions of JUnit, JUnit 5 is composed of several different modules from three different sub-projects. Furthermore, the platform provides a Console Launcher to launch the platform from the command line and a JUnit 4 based Runner for running any TestEngine on the platform in a JUnit 4 based environment. JUnit Jupiter is the combination of the new programming model and extension model for writing tests and extensions in JUnit 5. The Jupiter sub-project provides a TestEngine for running Jupiter based tests on the platform. JUnit 5 requires Java 8 or higher at runtime.
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Testing an application is an integral part of the development cycle, and writing and maintaining unit tests can help ensure that the individual methods in your source code work correctly.
The IDE's integrated support for the JUnit unit testing framework enables you to quickly and easily create JUnit tests and test suites. In this tutorial you create simple JUnit 3 and JUnit 4 unit tests and test suites for a Java class library project. The first part of the tutorial shows how to create tests in JUnit 3. The second part shows how to create the same tests in JUnit 4 using JUnit annotations. It is not necessary to complete both parts of the tutorial because the tests are the same, but seeing how the tests are written in both versions enables you to see some of the changes introduced in JUnit 4.
To perform the steps in this tutorial you need to install the JUnit plugin from the Update Center. To complete this tutorial you first create a Java class library project called JUnit-Sample. For this tutorial there is little reason to copy project libraries to a dedicated folder because you will not need to share libraries with other users or projects.
When you click Finish, the IDE initializes the local folder as a Subversion repository and checks out the project sources. In this exercise you copy the files Utils. If you look at the source code for the classes, you can see that Utils. The next step is to create test classes for each class and write some test cases for the methods.
You can close the JUnitSampleSol project because you will not need it again. The JUnitSampleSol project contains all the tests described in this document. In this part of the tutorial you create basic JUnit 3 unit tests for the classes Vectors. You will use the IDE to create skeleton test classes that are based on the classes in your project.
You will then modify the generated test methods and add new test methods. The version that you select becomes the default JUnit version and the IDE will generate all subsequent tests and test suites for that version. In this exercise you create a JUnit test skeleton for Vectors. You will also select JUnit as the test framework and JUnit 3 as the version. When you change the name of the test class, you will see a warning about changing the name. The default name is based on the name of the class you are testing, with the word Test appended to the name.
For example, for the class MyClass. Usually it is best to keep the default name, but for this tutorial you will change the name because you will also create JUnit 4 tests in the same package and the names of the test classes must be unique.
A project requires a directory for test packages to create tests. The default location for the test packages directory is at the root level of the project, but depending on the type of project you can specify a different location for the directory in the project's Properties dialog. If you look at the generated test class VectorsJUnit3Test. The method body of each generated test is provided solely as a guide and needs to be modified to be an actual test case.
You can deselect Default Method Bodies in the Create Tests dialog if you do not want the code generated for you. When the IDE generates the names for the test methods, each method name is prepended with test because JUnit 3 uses naming conventions and reflection to identify tests.
In JUnit 4 it is no longer necessary to use this test method naming syntax because you can use annotations to identify test methods and the test class is no longer required to extend TestCase. In this exercise you modify the generated test methods to make them functioning tests and modify the default output messages. You do not need to modify the output messages to run the tests, but you may want to modify the output to help identify the results displayed in the JUnit Test Results output window.
This test method uses the JUnit assertEquals method. To use the assertion, you supply the input variables and the expected result. To pass the test, the test method must successfully return all the expected results based on the supplied variables when running the tested method.
You should add a sufficient number of assertions to cover the various possible permutations. This test uses the JUnit assertTrue and assertFalse methods to test a variety of possible results. For the test of this method to pass, the assertTrue must all be true and assertFalse must all be false.
Compare: Writing Test Methods for Vectors. You now create the test skeletons for Utils. You are not prompted to select a version this time. You can see that in addition to creating the test skeletons testComputeFactorial , testConcatWords , and testNormalizeWord for the methods in Utils. In this exercise you add some test cases that illustrate some common JUnit test elements. You also add a println to the methods because some methods do not print any output by default.
By adding a println to the methods you can later look in the JUnit test result window to see if the methods were run and the order in which they were run. The setUp and tearDown methods are used to initialize and finalize test conditions.
You do not need the setUp and tearDown methods to test Utils. The setUp method is a test initialization method and is run before each test case in the test class. A test initialization method is not required for running tests, but if you need to initialize some variables before you run a test, you use the test initializer method.
The tearDown method is a test finalizer method and is run after each test case in the test class. A test finalizer method is not required for running tests, but you may need a finalizer to clean up any data that was required when running the test cases. When you run the test the println text for each methods will appear in the JUnit Test Results output window.
If you do not add the println , there is no output to show that the methods were run. This simple test case tests the concatWords method. Instead of using the generated test method testConcatWords , you will add a new test method called testHelloWorld that uses a single simple assertion to test if the method concatenates the strings correctly. In this case, if the input to the method concatWords is " Hello ", " , ", " world " and "! This test demonstrates how to check if a method is taking too long to complete.
If the method is taking too long, the test thread is interrupted and the test fails. You can specify the time limit in the test. The test method invokes the computeFactorial method in Utils. You can assume that the computeFactorial method is correct, but in this case you want to test if the computation is completed within milliseconds.
The computeFactorial thread and a test thread are started at the same time. The test thread will stop after milliseconds and throw a TimeoutException unless the computeFactorial thread completes first. You will add a message so that a message is displayed if a TimeoutException is thrown. You can modify the Thread. This test demonstrates how to test for an expected exception. The method fails if it does not throw the specified expected exception.
In this case you are testing that the computeFactorial method throws an IllegalArgumentException if the input variable is a negative number This test demonstrates how to temporarily disable a test method. In JUnit 3, if a method name does not start with test it is not recognized as a test method. Now that you have written the tests, you can run the test and see the test output in the JUnit Test Results window.
To run an individual test class, right-click the test class under the Test Packages node and choose Run File. When you run the test you will see one of the following results in the JUnit Test Results window. In this image click the image to see a larger image you can see that the project passed all the tests.
The left pane displays the results of the individual test methods and the right pane displays the test output. If you look at the output you can see the order that the tests were run. The println that you added to each of the test methods printed out the name of the test to the output window. You can also see that in UtilJUnit3Test the setUp method was run before each test method and the tearDown method was run after each method.
In this image click the image to see a larger image you can see that the project failed one of the tests. The testTimeout method took too long to complete and the test thread was interrupted, causing that test to fail.
It took longer than milliseconds to compute the factorial of the randomly generated number The next step after you create your unit test classes is to create test suites. See Creating JUnit 3 Test Suites to see how to run specified tests as a group so you do not have to run each test individually. In this exercise you create JUnit 4 unit tests for the classes Vectors.
The JUnit 4 test cases are the same as the JUnit 3 test cases, but you will see that the syntax for writing the tests is simpler. You will use the IDE's wizards to create test skeletons based on the classes in your project.
If you already selected JUnit 3. You can now use the Add Library dialog box to explicitly add the JUnit 4 library or you can select version 4. You can still run JUnit 3 tests, but any new tests you create will use JUnit 4.
Usually it is best to keep the default name, but because you are creating all the JUnit tests in the same package in this tutorial the names of the test classes have to be unique. The default location for the test packages directory is at the root level of the project, but you can specify a different location for the directory in the project's Properties dialog.
If you look at VectorsJUnit3Test. In VectorsJUnit4Test. The IDE generated the names for the test methods based on the names of the method in Vectors. The default body of each generated test method is provided solely as a guide and needs to be modified to be actual test cases. You can deselect Default Method Bodies in the Create Tests dialog if you do not want the bodies of the method generated for you. The IDE generates the class initializer and finalizer methods by default when creating JUnit 4 test classes.
Version 1. Read about the new features and fixes from April. It's a lightweight extension to run and debug Java test cases. The extension supports the following test frameworks:.
JUnit 5 User Guide
JUnit is a simple framework to write repeatable tests. It is an instance of the xUnit architecture for unit testing frameworks. Basic JUnit operation JUnitCore now more often exits with the correct exit code 0 for success, 1 for failure. Badly formed test classes exceptions in constructors, classes without tests, multiple constructors, Suite without SuiteClasses produce more helpful error messages. Optimization to annotation processing can cut JUnit overhead by more than half on large test classes, especially when using Theories. Annotating a class with RunWith JUnit4.