JUnit

Every JUnit test class usually has several test cases. These test cases are subject to the test life cycle. The full JUnit Lifecycle has three major phases:{{sfn|Gulati|Sharma|2017|loc=Chapter §2 JUnit LifeCycle API|pp=37-40}}

1. Setup phase - This phase is where the test infrastructure is prepared. Two levels of setup are available. The first type of setup is class-level setup in which a computationally expensive object, such as a database connection, is created and reused, with minimal side effects. Class-level setup is implemented using the {{code|@BeforeAll}} annotation. The other type is setup before running each test case, which uses the {{code|@BeforeEach}} annotation.{{sfn|Gulati|Sharma|2017|loc=Chapter §2 JUnit LifeCycle API|pp=37-40}}
2. Test execution - This phase is responsible for running the test and verifying the result. The test result will indicate if the test result is a success or a failure. The {{code|@Test}} annotation is used here.{{sfn|Gulati|Sharma|2017|loc=Chapter §2 JUnit LifeCycle API|pp=37-40}}
3. Clean up phase - After all posttest executions are performed, the system may need to perform cleanup. Similar to class-level setup, there is a corresponding class-level clean up. The {{code|@AfterAll}} annotation is used to support class-level clean up. The {{code|@AfterEach}} annotation allows for cleanup after test execution.{{sfn|Gulati|Sharma|2017|loc=Chapter §2 JUnit LifeCycle API|pp=37-40}}

JUnit 5 integrates a number of tools, such as build tools, integrated development environments (IDE), continuous integration (CI) tools and many more.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools|p=99}}

{{main article | Build tool }}

JUnit supports Apache Ant, Apache Maven and Gradle build tools, which are the most widely used project build tools.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Build Tools|pp=99-117}} Build tools are vital for automating the process of building the project. {{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools|p=99}}

{{main article | Apache Ant }}

Apache Ant, also known as Ant, is one of the build tools with the highest degree of versatility, and has the longest history out of the three build tools listed above.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Ant|pp=108-112}} Ant centers around the build.xml file, used for configuring the tasks necessary to run a project.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Ant|pp=108-112}} Ant also has an extension called Apache Ivy, which helps deal with dependency resolution. The project dependencies can be declared in the ivy.xml file. Ant can integrate with JUnit 5 by configuring the Java code coverage tools (JaCoCo), for the ivy.xml file.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Ant|pp=108-112}} The ivy.xml can then be configured with the java-platform-console and junit-platform-runner dependencies to integrate with JUnit 5. {{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Ant Extension|pp=116-117}}

{{main article | Apache Maven}}

In contrast to Ant, Apache Maven, also known as Maven, uses a standardized and unified approach to the build process.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Maven|pp=104-108}} Maven follows the paradigm of "convention over configuration" for managing its dependencies.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Gradle|pp=99-103}} The Java source code (or "src") can be found under the src/main/java directory, and the test files can be found under the src/test/java directory.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Gradle|pp=99-103}} Maven can be used for any Java Project.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Maven|pp=104-108}} It uses the Project Object Model (POM), which is an XML-based approach to configuring the build steps for the project.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Maven|pp=104-108}} The minimal Maven with the pom.xml build file must contain a list of dependencies and a unique project identifier.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Maven|pp=104-108}} Maven must be available on the build path to work.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Maven|pp=104-108}} Maven can integrate with JUnit 5 using the jacoco-maven-plugin plugin which supports out-of-box functionality for JUnit 5 tests.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Maven Extension|p=115}} Different Maven goals can be specified to achieve these tasks.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Maven Extension|p=115}}

{{main article | Gradle}}

Gradle is a build tool that borrows many concepts from its predecessors, Ant and Maven.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Gradle|pp=99-103}} It uses the {{code|build.gradle}} file to declare the steps required for the project build.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Gradle|pp=99-103}} Unlike Ant and Maven, which are XML-based, Gradle requires the use of Apache Groovy, which is a Java-based programming language.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Gradle|pp=99-103}} Unlike Ant and Maven, Gradle does not require the use of XML.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Gradle|pp=99-103}} Gradle still adheres to Maven's "convention over configuration" approach, and follows the same structure for {{code|src/main/java}} and {{code|src/test/java}} directories.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Gradle|pp=99-103}} Gradle can integrate with JUnit 5 by configuring a plugin {{code|jacoco}} alongside the junit-platform plug-in given by the JUnit 5 team in the build file.{{sfn|Gulati|Sharma|2017|loc=Chapter §6 Integrating Tools - Build Tools - Gradle Extension|pp=113-114}}

JUnit follows the paradigm of preferring extension points over features.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 5 Extension Model|p=121}} The JUnit team decided not to put all features within the JUnit core, and instead decided to give an extensible way for developers to address their concerns.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 5 Extension Model|p=121}}

In JUnit 4, there are two extension mechanisms: the Runner API and Rule API.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 4 Extension Model|pp=121-122}} There were some disadvantages to both the Runner API and the Rule API.

A major limitation of the Runner API is that developers must implement the entire test lifecycle, even if only a specific phase is required.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 4 Extension Model|pp=121-122}} This is too complicated and heavyweight for most use cases.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 4 Extension Model|pp=121-122}} Another major limitation is that only one runner class can be used per test case, which makes runners non-composable.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 4 Extension Model|pp=121-122}} For example, Mockito and Parameterized runners cannot be used together within the same test class.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 4 Extension Model|pp=121-122}}

A major limitation of the Rule API is that it cannot control the entire test lifecycle and is therefore unsuitable for certain use cases.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 4 Extension Model|pp=121-122}} Rules are only suitable for operations that need to run before or after test execution.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 4 Extension Model|pp=121-122}} Another limitation is that class-level and method-level rules must be defined separately.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 4 Extension Model|pp=121-122}}

In JUnit 5, the extension API is found within the JUnit Jupiter Engine.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 5 Extension Model - JUnit 5 Extension Model|pp=122-124}} The JUnit Team wants to allow the developer to hook to separate stages of a test life cycle by providing a single unified extension API.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 5 Extension Model - JUnit 5 Extension Model|pp=122-124}} Upon reaching a certain life cycle phase, the Jupiter Engine will invoke all registered extensions for that phase.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 5 Extension Model - JUnit 5 Extension Model|pp=122-124}} The developer can hook into five major extension points:{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 5 Extension Model - JUnit 5 Extension Model|pp=122-124}}

1. Test lifecycle callbacks – allow developers to execute code at specific test lifecycle phases.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 5 Extension Model - Test Life Cycle Callbacks|pp=124-126}}
2. Test instance post-processing – enables developers to hook into the test instance creation phase using the TestInstancePostProcessor interface.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 5 Extension Model - Test Instance Post-Processing|pp=126-127}}
3. Conditional test execution – allows tests to run only if certain conditions are met.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 5 Extension Model - Conditional Test Execution|p=127}}
4. Parameter resolution – allows parameters to be injected into test methods or constructors.
5. Exception handling – allows developers to modify test behavior in response to exceptions instead of failing the test outright.{{sfn|Gulati|Sharma|2017|loc=Chapter §7 JUnit 5 Extension Model - Exception Handling|p=129}}

A JUnit test fixture is a Java object. Test methods must be annotated by the {{code|@Test}} annotation. If the situation requires it,{{cite web

| url=http://c2.com/cgi/wiki?ExpensiveSetUpSmell

| title=Expensive Setup Smell

| publisher=C2 Wiki

| author=Kent Beck

| author-link=Kent Beck

| access-date=2011-11-28}} it is also possible to define a method to execute before (or after) each (or all) of the test methods with the {{code|@BeforeEach}} (or {{code|@AfterEach}}) and {{code|@BeforeAll}} (or {{code|@AfterAll}}) annotations.{{cite web | url=https://junit.org/junit5/docs/current/user-guide/#writing-tests | title=Writing Tests | website=junit.org | access-date=2021-02-04}}{{sfn|Gulati|Sharma|2017|loc=Chapter §2 Understanding CoreJunit 5|p=37-40}}

import org.junit.jupiter.api.*;

class FoobarTests {

@BeforeAll

static void setUpClass() throws Exception {

// Code executed before the first test method

}

@BeforeEach

void setUp() throws Exception {

// Code executed before each test

}

@Test

void oneThing() {

// Code that tests one thing

}

@Test

void anotherThing() {

// Code that tests another thing

}

@Test

void somethingElse() {

// Code that tests something else

}

@AfterEach

void tearDown() throws Exception {

// Code executed after each test

}

@AfterAll

static void tearDownClass() throws Exception {

// Code executed after the last test method

}

}

According to Martin Fowler, one of the early adopters of JUnit:{{Cite web |title=bliki: Xunit |url=https://martinfowler.com/bliki/Xunit.html |access-date=2022-03-07 |website=martinfowler.com}}

{{Blockquote

|text=JUnit was born on a flight from Zurich to the 1997 OOPSLA in Atlanta. Kent was flying with Erich Gamma, and what else were two geeks to do on a long flight but program? The first version of JUnit was built there, pair programmed, and done test first (a pleasing form of meta-circular geekery).}}

As a side effect of its wide use, previous versions of JUnit remain popular, with JUnit 4 having over 100,000 usages by other software components on the Maven Central repository.{{cite web | url=https://mvnrepository.com/artifact/junit/junit/usages | title=JUnit | website=mvnrepository.com | access-date=29 October 2021}}

In JUnit 4, the annotations for test execution callbacks were {{code|@BeforeClass}}, {{code|@Before}}, {{code|@After}}, and {{code|@AfterClass}}, as opposed to JUnit 5's {{code|@BeforeAll}}, {{code|@BeforeEach}}, {{code|@AfterEach}}, and {{code|@AfterAll}}.{{sfn|Gulati|Sharma|2017|loc=Chapter §2 Understanding CoreJunit 5|p=37-40}}

In JUnit 3, test fixtures had to inherit from {{code|junit.framework.TestCase}}.{{cite web

| url=http://junit.sourceforge.net/doc/cookbook/cookbook.htm

| title=JUnit Cookbook

| publisher=junit.sourceforge.net

| author1=Kent Beck

| author2=Erich Gamma

| author-link1=Kent Beck

| author-link2=Erich Gamma

| access-date=2011-05-21

| archive-date=2020-06-15

| archive-url=https://web.archive.org/web/20200615030913/http://junit.sourceforge.net/doc/cookbook/cookbook.htm

| url-status=dead

}} Additionally, test methods had to be prefixed with 'test'.{{cite web | url=https://objectcomputing.com/resources/publications/sett/august-2007-migrating-from-junit-3-to-junit-4-nothing-but-good-news | title=Migrating from JUnit 3 to JUnit 4: Nothing But Good News | publisher=Object Computing, Inc. | author1=Charles A. Sharp | date=August 2007 | access-date=2021-02-04}}

{{Portal|Free and open-source software}}

• xUnit, the family name given to testing frameworks including JUnit
• SUnit, the original Smalltalk version written by Kent Beck based on which JUnit was written
• TestNG, another test framework for Java
• Mock object, a technique used during unit testing
• Mockito, a mocking library to assist in writing tests
• EvoSuite, a tool to automatically generate JUnit tests
• List of Java Frameworks

{{Reflist}}

• {{cite book | last=Gulati | first=Shekhar | last2=Sharma | first2=Rahul | title=Java Unit Testing with JUnit 5 | publisher=Apress | publication-place=Berkeley, CA | year=2017 | isbn=978-1-4842-3014-5 | doi=10.1007/978-1-4842-3015-2}}

• {{Official website|https://junit.org}}
• {{cite web |url= http://www.methodsandtools.com/tools/tools.php?junit |title= JUnit - Open Source Java Unit Testing Tool |website= Methods and Tools |first= Axel |last= Irriger }}
• {{cite web |url= http://memorynotfound.com/category/testing/junit |title= JUnit |series= Tutorials |website= Memory Not Found |url-status= live |archive-date= Jan 28, 2015 |archive-url= https://web.archive.org/web/20150128114403/http://memorynotfound.com/category/testing/junit }}

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