JUnit5 is the unit testing framework for the Java language, and it is the latest version of the JUnit framework. JUnit5 provides many new features and improvements, including new annotations and assertions, as well as integration with Java 8, making writing, organizing, and executing unit tests more flexible and powerful. The core modules of JUnit5 can be introduced through the following Maven dependencies: ```xml <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-api</artifactId> <version>5.7.0</version> <scope>test</scope> </dependency> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-engine</artifactId> <version>5.7.0</version> <scope>test</scope> </dependency> ``` Below is an introduction to some commonly used key methods of JUnit5 and Java sample code: 1. '@ Test' annotation: used to identify the testing method. ```java import org.junit.jupiter.api.Test; public class MyTest { @Test public void myTestMethod() { //Test Code } } ``` 2. '@ BeforeAll' annotation: used to identify methods that are executed before all test methods. ```java import org.junit.jupiter.api.BeforeAll; import org.junit.jupiter.api.Test; public class MyTest { @BeforeAll public static void setup() { //Initialization operation } @Test public void myTestMethod() { //Test Code } } ``` 3. '@ BeforeEach' annotation: used to identify the method that was executed before each test method. ```java import org.junit.jupiter.api.BeforeEach; import org.junit.jupiter.api.Test; public class MyTest { @BeforeEach public void setup() { //Initialization operation } @Test public void myTestMethod() { //Test Code } } ``` 4. '@ AfterAll' annotation: used to identify the method to be executed after all test methods. ```java import org.junit.jupiter.api.AfterAll; import org.junit.jupiter.api.Test; public class MyTest { @AfterAll public static void cleanup() { //Cleaning operation } @Test public void myTestMethod() { //Test Code } } ``` 5. '@ AfterEach' annotation: used to identify the method to be executed after each test method. ```java import org.junit.jupiter.api.AfterEach; import org.junit.jupiter.api.Test; public class MyTest { @AfterEach public void cleanup() { //Cleaning operation } @Test public void myTestMethod() { //Test Code } } ``` 6. '@ DisplayName' annotation: Used to specify the display name of the test method. ```java import org.junit.jupiter.api.DisplayName; import org.junit.jupiter.api.Test; public class MyTest { @DisplayName ("My Test Method") @Test public void myTestMethod() { //Test Code } } ``` The above is an introduction to some commonly used key methods and annotations of JUnit5, as well as the corresponding Java sample code. JUnit5 also provides more features and annotations that can be used according to specific needs.

TestNG is a Java based testing framework used for writing and executing unit tests. It provides a wide range of functions and flexibility, can easily create, configure and run Test suite, and provides powerful reporting and logging functions. TestNG also supports advanced functions such as concurrent testing, parameterized testing, dependency testing, and skip testing. The most commonly used key methods in TestNG are: 1. @ Test annotation: Use @ Test annotation to mark a testing method. By using the @ Test annotation, you can specify properties such as priority, timeout, and whether to enable the testing method. 2. @ BeforeMethod and @ AfterMethod annotations: Use the @ BeforeMethod annotation to execute once before each test method is executed, and use the @ AfterMethod annotation to execute once after each test method is executed. These methods can be used to set up initialization operations before testing and cleaning operations after testing. 3. @ BeforeClass and @ AfterClass annotations: Use the @ BeforeClass annotation to execute once before all test methods in the entire test class are executed, and use the @ AfterClass annotation to execute once after all test methods are executed. These methods can be used to perform class level initialization and cleanup operations. 4. @ DataProvider annotation: Use @ DataProvider annotation to provide test data. By using @ DataProvider annotations, test data can be separated from test methods to achieve data-driven testing. The following is a simple Java sample code for unit testing using TestNG: ```java import org.testng.Assert; import org.testng.annotations.*; public class TestClass { @BeforeClass public void setUpClass() { //Initialize operation, execute once } @AfterClass public void tearDownClass() { //Clean up operation, execute once } @BeforeMethod public void setUp() { //Initialization operation, each test method will be executed once before execution } @AfterMethod public void tearDown() { //Cleanup operation, each test method will be executed once after execution } @Test(priority = 1) public void testMethod1() { //Test Method 1 Assert.assertTrue(true); } @Test(priority = 2) public void testMethod2() { //Test Method 2 Assert.assertEquals(1, 1); } @DataProvider(name = "testData") public Object[][] testData() { return new Object[][] { { "data1" }, { "data2" } }; } @Test(dataProvider = "testData") public void testMethodWithDataProvider(String data) { //Using test data for testing Assert.assertNotNull(data); } } ``` The above code uses TestNG annotations to mark the testing method and set up the testing environment, and demonstrates how to use @ DataProvider annotations to provide testing data. The methods in the test class are executed according to the set priority, and the results are verified using assertions. If Maven is used to build a project, the following dependencies can be added to the 'pom. xml' file to introduce TestNG: ```xml <dependencies> <dependency> <groupId>org.testng</groupId> <artifactId>testng</artifactId> <version>7.4.0</version> <scope>test</scope> </dependency> </dependencies> ``` By adding the above dependencies, Maven can be used to download and manage the TestNG framework.

Mockito is an open source unit testing framework for Java, which can help developers create and manage Mock object during testing. The core idea of Mockito is to use Mock object instead of real objects to better control the test environment and test results. By using Mock object, we can simulate various behaviors and states required for testing, so as to achieve effective, reliable and efficient testing of the code under test. The commonly used key methods of Mockito include: 1. mock(Class<T> classToMock) -Used to create a Mock object of the specified class. ```java List<String> mockedList = Mockito.mock(List.class); ``` 2. when(mockedObject.methodCall()).thenReturn(result) -Defines that when a method of a Mock object is called, the specified result is returned. ```java when(mockedList.get(0)).thenReturn("first"); ``` 3. verify(mockedObject, times(num)).methodCall() -Verify that a method of the Mock object has been called the specified number of times. ```java verify(mockedList, times(1)).add("one"); ``` 4. doThrow(exceptionClass).when(mockedObject).methodCall() -Defines that the specified exception will be thrown when a method of the Mock object is called. ```java doThrow(new RuntimeException()).when(mockedList).clear(); ``` 5. ArgumentMatchers -Mockito also provides the ArgumentMatchers class, which is used to flexibly match parameters in method calls of Mock object. ```java when(mockedList.get(anyInt())).thenReturn("element"); ``` Mockito can be added to a project through the following Maven dependencies: ```xml <dependency> <groupId>org.mockito</groupId> <artifactId>mockito-core</artifactId> <version>3.9.0</version> <scope>test</scope> </dependency> ``` The above is a brief introduction to Mockito and sample code of commonly used key methods. By using these methods, we can achieve precise and controllable unit testing of the tested code.

PowerMock is a unit testing framework used to enhance JUnit and TestNG, which allows developers to simulate and modify static methods, private methods, and constructors in code during unit testing. PowerMock is based on Mockito and EasyMock, providing Java developers with a more flexible and powerful testing tool. The following is an introduction to the key methods commonly used by PowerMock and Java sample code: 1. Mock static method Use the PowerMockito. mockStatic method to create a Mock object of a static method. ```java @RunWith(PowerMockRunner.class) @PrepareForTest (StaticClass. class)//The static class that needs to be simulated public class MyTest { @Test public void testStaticMethod() { PowerMockito. dockStatic (StaticClass. class)// Create a Mock object for a static method //Set the return value of Mock object Mockito.when(StaticClass.staticMethod()).thenReturn("mocked value"); //Calling the tested method (static method called) String result = myObject.doSomething(); //Verification results Assert.assertEquals("mocked value", result); //Verify that the static method was called once PowerMockito.verifyStatic(StaticClass.class, Mockito.times(1)); StaticClass.staticMethod(); } } ``` 2. Mock Private Method Use the PowerMockito. whenNew method to create a Mock object for a private constructor. Then, you can use the Mockito. when method to set the behavior of the Mock object. ```java @RunWith(PowerMockRunner.class) @PrepareForTest (MyClass. class)//The class that needs to be simulated public class MyTest { @Test public void testPrivateMethod() throws Exception { MyClass myObject=PowerMockito. lock (MyClass. class)// Create a Mock object of the tested class //Create a Mock object for a private constructor MyObject mockedObject = PowerMockito.whenNew(MyObject.class) .withNoArguments().thenReturn(myObject); //Set the behavior of the Mock object PowerMockito.when(myObject, "privateMethod").thenReturn("mocked value"); //Calling the tested method (private method called) String result = myObject.doSomething(); //Verification results Assert.assertEquals("mocked value", result); //Verify that the private method was called once PowerMockito.verifyPrivate(myObject, Mockito.times(1)).invoke("privateMethod"); } } ``` There are other powerful features to using PowerMock and PowerMockito, such as simulating constructor parameters, simulating final methods, and so on. For details, please refer to the official documentation and sample code of PowerMock. If you need to use PowerMock, you can add the following dependencies in the pom.xml file of the project: ```xml <dependency> <groupId>org.powermock</groupId> <artifactId>powermock-module-junit4</artifactId> <version>2.0.9</version> <scope>test</scope> </dependency> <dependency> <groupId>org.powermock</groupId> <artifactId>powermock-api-mockito2</artifactId> <version>2.0.9</version> <scope>test</scope> </dependency> ```

Spock is a testing framework based on Groovy language, which provides rich DSL (Domain-specific language) to write unit tests. Spock can test both Java code and Groovy code, and it is based on JUnit and highly compatible with JUnit. Spock is characterized by its ease of reading, writing, and maintenance. Below are several key methods commonly used in Spock and corresponding Java sample codes: 1. 'given()': Used to set preset conditions for the testing environment. ```java given: def list = new ArrayList<String>() ``` 2. 'when()': Used to call the tested method or trigger the event to be tested. ```java when: list.add("item") ``` 3. 'then()': Used to verify whether the test results meet expectations. ```java then: list.size() == 1 list.contains("item") ``` 4. 'expectations {}': used to define the expected behavior of a method call. ```java given: def calculator = Mock(Calculator) when: def result = calculator.add(2, 3) then: result == 5 expectations: 1 * calculator.add(2, 3) >> 5 ``` 5. 'cleanup()': Used to clean up test data or resources. ```java cleanup: //Clean up code ``` 6. '@ SpockTest': Used to mark the test class to enable it to run Spock tests. ```java @SpockTest class MyUnitTest { } ``` Spock uses Maven for dependency management and needs to add the following Maven dependencies to the project's' pom. xml 'file: ```xml <dependency> <groupId>org.spockframework</groupId> <artifactId>spock-core</artifactId> <version>2.0-M2-groovy-2.5</version> <scope>test</scope> </dependency> ``` When writing test classes, you can use the annotations and keywords provided by Spock to write test code. The above are just some common methods and usage in Spock, which provides more features and flexibility to meet different testing needs.

DbUnit is an open source Java testing framework used to perform database unit testing. It uses JUnit and DB connection technology to perform testing, and can set the state of the database from a known initial state to a known end state before and after testing. The following are the general steps for using DbUnit for unit testing: 1. Prepare test data: Use an XML or CSV format dataset file that contains the initial data required for testing. 2. Initialize database connection: Use appropriate DB connection techniques to connect to the database and create an IDatabaseConnection object. 3. Set the dataset: Use the IDataSet interface to represent the initial data required for testing, and import the dataset using the DatabaseConnection object. 4. Execute testing: In JUnit unit testing, create a DbUnitTestCase object using the DataSet and DatabaseConnection objects, and execute custom testing methods. 5. Clean up data: After testing, use the DatabaseConnection object to delete or rollback any changes made during testing. The following is an introduction and sample code for some commonly used DbUnit methods: 1. 'DatabaseConnection': Used to establish database connections and import/export datasets. ```java import org.dbunit.database.DatabaseConnection; import org.dbunit.dataset.IDataSet; import org.dbunit.dataset.xml.FlatXmlDataSetBuilder; //Initialize database connection IDatabaseConnection connection = new DatabaseConnection(dataSource.getConnection()); //Import Dataset IDataSet dataSet = new FlatXmlDataSetBuilder().build(new FileInputStream("dataset.xml")); connection.insert(dataSet); ``` 2. 'Dataset': represents the dataset in the database. ```java import org.dbunit.dataset.IDataSet; import org.dbunit.dataset.xml.FlatXmlDataSetBuilder; //Creating a DataSet object using an XML dataset file IDataSet dataSet = new FlatXmlDataSetBuilder().build(new FileInputStream("dataset.xml")); ``` 3. 'DbUnitTestCase': Used to create test cases and execute test methods. ```java import org.dbunit.dataset.IDataSet; import org.dbunit.operation.DatabaseOperation; import org.dbunit.util.fileloader.FlatXmlDataFileLoader; public class MyTest extends DbUnitTestCase { @Override protected void setUp() throws Exception { //Set the dataset before testing FlatXmlDataFileLoader loader = new FlatXmlDataFileLoader(); IDataSet dataSet = loader.load("/dataset.xml"); backupRestore = new BackupRestore(getConnection().getConnection(), dataSet); } @Override protected void tearDown() throws Exception { //Clean up the data after testing backupRestore.restore(); } //Custom Test Method public void testSomething() { //Perform Test Operations // ... } } ``` The above example code depends on the Maven coordinates of DbUnit and JUnit: ```xml <dependency> <groupId>org.dbunit</groupId> <artifactId>dbunit</artifactId> <version>2.7.0</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </dependency> ```

WireMock is a Java library used to simulate HTTP services, which can help developers write and run Test automation for unit testing. WireMock can run as an independent HTTP server, configure expected HTTP requests and responses, and record detailed information on executing requests. It can be used to simulate back-end services for independent Integration testing. Here are the common methods and Java sample code for WireMock: 1. Initialize and shut down WireMock server: ```java import com.github.tomakehurst.wiremock.WireMockServer; import static com.github.tomakehurst.wiremock.core.WireMockConfiguration.options; WireMockServer wireMockServer; @Before public void setup() { wireMockServer = new WireMockServer(options().port(8080)); wireMockServer.start(); } @After public void tearDown() { wireMockServer.stop(); } ``` 2. Create and match requests: ```java import static com.github.tomakehurst.wiremock.client.WireMock.*; stubFor(get(urlEqualTo("/api/user")) .willReturn(aResponse() .withStatus(200) .withHeader("Content-Type", "application/json") .withBody("{\"username\": \"john\", \"email\": \"john@example.com\"}"))); ``` The above code creates a stub of a GET request. When the URL of the request is "/api/user", the List of HTTP status codes 200 is returned, the Content Type is "application/json", and the response body is a JSON string. 3. Verify the call of the request: ```java import static com.github.tomakehurst.wiremock.client.WireMock.*; verify(getRequestedFor(urlEqualTo("/api/user"))); ``` The above code verifies whether there is a call with a GET request URL of "/api/user". 4. Set latency and response time: ```java import static com.github.tomakehurst.wiremock.client.WireMock.*; stubFor(get(urlEqualTo("/api/user")) .willReturn(aResponse() .withStatus(200) . withFixedDelay (1000))// Set a delay of 1 second to return the response ``` The above code causes a delay of 1 second before the request returns a response. 5. Set the criteria for request matching: ```java import static com.github.tomakehurst.wiremock.client.WireMock.*; stubFor(get(urlMatching("/api/user.*")) .withQueryParam("id", equalTo("123")) .willReturn(aResponse() .withStatus(200))); ``` The above code uses a regular expression to match the URL, and the requested parameter id must be equal to '123'. Maven Dependency: ```xml <dependency> <groupId>com.github.tomakehurst</groupId> <artifactId>wiremock</artifactId> <version>2.27.2</version> <scope>test</scope> </dependency> ``` The above is an introduction to unit testing using WireMock and sample code for commonly used methods.

AssertJ is a fluent assertion library for writing more readable and maintainable Java unit test assertions. It provides multiple assertion methods to verify the expected results of testing and can be used in conjunction with testing frameworks such as JUnit and TestNG. The main features of AssertJ include: 1. Use smooth API: AssertJ's assertion method adopts a chain call approach, making the assertion statements more readable and reducing the repetition of test code. 2. Provided rich assertion methods: AssertJ provides a large number of assertion methods for verifying the state, behavior, etc. of objects. For example, assertion methods can be used to verify the value of an object, the size of a collection, the content of a string, and so on. 3. Provided readable error information: When the assertion fails, AssertJ provides detailed error information, allowing developers to quickly locate the problem and fix it. Before using AssertJ for unit test assertions, it is necessary to first add the dependencies of AssertJ. In the Maven project, the following dependencies can be added to the pom.xml file: ```xml <dependency> <groupId>org.assertj</groupId> <artifactId>assertj-core</artifactId> <version>3.21.0</version> <scope>test</scope> </dependency> ``` Below are several commonly used AssertJ assertion methods and their usage examples: 1. assertThat: Used to assert an object and determine whether a certain condition is met. ```java import static org.assertj.core.api.Assertions.assertThat; public class ExampleTest { @Test public void testAssertThat() { String text = "Hello World"; assertThat(text).isEqualTo("Hello World"); assertThat(text).contains("Hello"); assertThat(text).startsWith("Hello"); assertThat(text).endsWith("World"); } } ``` 2. assertAll: Used to combine multiple assertions and test whether multiple conditions are met. ```java import static org.assertj.core.api.Assertions.*; public class ExampleTest { @Test public void testAssertAll() { Person person = new Person("John", 30); assertAll( () -> assertThat(person.getName()).isEqualTo("John"), () -> assertThat(person.getAge()).isGreaterThan(20), () -> assertThat(person.getAge()).isLessThan(40) ); } } ``` 3. assertThrows: Used to test whether a code block will throw a specific exception. ```java import static org.assertj.core.api.Assertions.*; public class ExampleTest { @Test public void testAssertThrows() { assertThatThrownBy(() -> { // some code that throws an exception throw new IllegalArgumentException(); }).isInstanceOf(IllegalArgumentException.class); } } ``` The above are some commonly used methods of AssertJ, through which diverse assertions can be made to better write unit tests.

Hamrest is a framework for writing unit test assertions. It provides a set of methods that can be used to compare and validate relationships between objects, making it easier to read and test assertions for expressions. The commonly used Hamrest key methods include: 1. EqualTo(): Used to compare whether two objects are equal. ```java import static org.hamcrest.MatcherAssert.assertThat; import static org.hamcrest.Matchers.equalTo; assertThat(actualValue, equalTo(expectedValue)); ``` 2. is(): Used to determine whether the object meets specific conditions. ```java import static org.hamcrest.MatcherAssert.assertThat; import static org.hamcrest.Matchers.is; assertThat(actualValue, is(expectedValue)); ``` 3. not(): Used to determine whether the object does not meet specific conditions. ```java import static org.hamcrest.MatcherAssert.assertThat; import static org.hamcrest.Matchers.not; assertThat(actualValue, not(expectedValue)); ``` 4. containsString(): Used to determine whether a string contains a specified substring. ```java import static org.hamcrest.MatcherAssert.assertThat; import static org.hamcrest.Matchers.containsString; assertThat(actualString, containsString(expectedSubstring)); ``` In order to use Hamrest, the following dependencies need to be added to the pom.xml file in the Maven project: ```xml <dependency> <groupId>org.hamcrest</groupId> <artifactId>hamcrest-all</artifactId> <version>1.3</version> <scope>test</scope> </dependency> ``` This will add the Hamrest framework and all Matcher classes to the project for writing unit test assertions. Then, you can use the above example code to write more readable and expressive assertions.