Junit Platform Launcher framework technical principle analysis in Java class library
Junit Platform Launcher framework technical principle analysis in Java class library
Junit is one of the unit testing frameworks widely used by Java programmers.As one of the core components of Junit 5, Junit Platform LaNcher is responsible for loading, executing and managing the resources and environment of test operations.This article will introduce the technical principles of the Junit Platform Launcher framework and provide some Java code examples.
Introduction to the framework of Junit Platform Launcher
Junit Platform Launcher is one of the core components of the Junit framework, which is used to load, perform and manage test operations.It provides a general way to run different types of test engines and allows users to start test operations in various ways.
The core category of Junit Platform Launcher is Launcher, which provides a set of APIs to load and perform tests.In Junit 5, Launcher is mainly responsible for the following functions:
1. Start the test engine: According to the type and configuration of the test engine, Launcher will load the corresponding test engine instance.The test engine interface in Junit 5 is Testengine, and each test engine must implement this interface.
2. Loading and parsing test discovery: Test discovery is responsible for finding and identifying the test class and testing methods on a given class.Launcher will load and analyze the test discoverer, and then pass the detected test and methods to the test engine for execution.
3. Execute test: Launcher executes the test by calling the API of the test engine. During the execution, it can collect and report the test results.
4. Event and listener support: Junit 5 introduces event and monitoring mechanism. Launcher supports registration and triggering various test events, and allows users to customize and expand the incident listener.
2. The technical principles of Junit Platform Launcher
Junit Platform Launcher mainly uses the following steps to achieve the loading and execution of the test:
1. Build Launcher instance: Users can create Launcher instances through LauncherFactory, or use LauncherDiscoveryRequestBuilder to configure Launcher.
2. Initialize test engine: Launcher is responsible for loading and initialization test engines. According to the configured test engine type and parameters, the corresponding test engine instance is loaded.
3. Loading and parsing test discovery: Launcher will load the corresponding test discoverers based on the configuration test discovery, and use the test discovery to find and identify the test class and methods.
4. Execute test: Launcher executes the test by calling the API of the test engine, and the test engine will perform the test in the specified manner.
5. Surveillance test event: Launcher is responsible for registration and triggering various test events. It calls the registered monitor and conveys the corresponding event information.
The following is a simple example of a Junit Platform Launcher:
import org.junit.platform.launcher.Launcher;
import org.junit.platform.launcher.LauncherDiscoveryRequest;
import org.junit.platform.launcher.core.LauncherFactory;
import org.junit.platform.launcher.listeners.TestExecutionSummary;
public class JUnitPlatformLauncherExample {
public static void main(String[] args) {
LauncherDiscoveryRequest request = LauncherDiscoveryRequestBuilder.request()
.selectors(selectPackage("com.example.tests"))
.build();
Launcher launcher = LauncherFactory.create();
TestExecutionSummary summary = launcher.execute(request);
Summary.printto (System.out); // Print test running results
}
}
In the above example, we first created a LauncherDiscoveryRequest instance that specifies the test package to run.Then we created a Launcher instance through LauncherFactory.Finally, we call the EXECUTE method of Launcher to perform the test operation and print the operation results to the console.
3. Summary
Junit Platform Launcher is one of the core components of Junit 5 and is responsible for loading, execution and management test operations.By using Junit Platform Launcher, we can flexibly load and perform different types of testing, and can register and trigger various test events.Through the introduction of this article, it is hoped that readers can understand the technical principles of Junit Platform Launcher and be able to apply it flexibly in actual projects.
