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Testing Java with Visual Studio Code

Testing Java in Visual Studio Code is enabled by the Test Runner for Java extension. It's a lightweight extension to run and debug Java test cases.

Overview

The extension supports the following test frameworks:

The Test Runner for Java works with the Language Support for Java™ by Red Hat and Debugger for Java extensions to provide the following features:

  • Run/Debug test cases
  • Customize test configurations
  • View test report
  • View tests in Testing Explorer

Requirements

Install the Extension Pack for Java

Project Setup

Note: If you have already setup your Java test framework in your project, you can skip to the Features section.

Enable testing and adding test framework JARs to your project

Starting with Test Runner for Java version 0.34.0, you can enable a test framework for your unmanaged folder project (a project without any build tools) with just a few steps in the Testing Explorer:

Note: Currently this feature only supports unmanaged folders that do not contain any testing dependencies.

JUnit 4

Maven

Add following configuration into your pom.xml:

<dependency>
  <groupId>junit</groupId>
  <artifactId>junit</artifactId>
  <version>(YOUR_JUNIT_VERSION)</version>
  <scope>test</scope>
</dependency>

Gradle

Make sure following lines are added in your build.gradle:

plugins {
    java
}

dependencies {
    testImplementation('junit:junit:(YOUR_JUNIT_VERSION)')
}

Unmanaged folder

If your project does not use any build tools, you can enable JUnit 4 via the Testing Explorer or by manually downloading the following JARs and adding them to the project classpath (via setting java.project.referencedLibraries, check Dependency management for more information):

You can check the official JUnit Wiki for more information about how to setup JUnit 4.

JUnit 5

The JUnit 5 team provides a collection of sample projects with different build tools. Check the junit5-sample repository if your project uses Maven or Gradle as your build tool.

Unmanaged folder

If your project does not use any build tools, you can enable JUnit 5 via the Testing Explorer or by manually including the junit-platform-console-standalone JAR in the project classpath (via setting java.project.referencedLibraries, check Dependency management for more information).

TestNG

Maven

Add following configuration into your pom.xml:

<dependency>
  <groupId>org.testng</groupId>
  <artifactId>testng</artifactId>
  <version>(YOUR_TESTNG_VERSION)</version>
  <scope>test</scope>
</dependency>

Gradle

Make sure following lines are added in your build.gradle:

plugins {
    java
}

dependencies {
    testImplementation('org.testng:testng:(YOUR_TESTNG_VERSION)')
}

Unmanaged folder

If your project does not use any build tools, you can enable TestNG via the Testing Explorer or by manually downloading the following JARs and adding them to the project classpath (via setting java.project.referencedLibraries, check Dependency management for more information):

Features

Run/Debug test cases

The Test Runner for Java extension will generate shortcuts (the green play button) on the left side of the class and method definition. To run the target test cases, select the green play button. You can also right-click on it to see more options.

Testing Explorer

The Testing Explorer is a tree view to show all the test cases in your workspace. You can select the beaker button on the left-side Activity bar of Visual Studio Code to open it. You can also run/debug your test cases and view their test results from there.

Customize test configurations

Sometimes you may want to customize the configuration to run your test cases. To achieve this, you can add the configuration into your workspace settings under the section: java.test.config.

Customize test configurations

Currently the supported configurations are:

  • args: Specify the command-line arguments that will be passed to the test runner.
  • classPaths: The classpaths defined in this setting will be appended to the resolved classpaths.
  • env: Specify the extra environment variables when running the tests via a key-value object.
  • envFile: Specify the absolute path to a file containing environment variable definitions.
  • modulePaths: The modulepaths defined in this setting will be appended to the resolved modulepaths.
  • name: Specify the name of the configuration item. You can set the default configuration name via setting java.test.defaultConfig.
  • preLaunchTask: Specify the label of a task specified in tasks.json (in the workspace's .vscode folder). The task will be launched before the start of testing.
  • sourcePaths: Specify the extra source paths when debugging the tests.
  • vmArgs: Specify the extra options and system properties for the JVM.
  • workingDirectory: Specify the working directory when running the tests.
  • testKind: Specify the targeting test framework for this test configuration. Supported values are junit, testng.
  • filters: Specify the test filters.
    • tags: Specify the tags to be included or excluded. Tags having ! as the prefix will be excluded. Note: This setting only takes effect when testKind is set to junit

More details can be found on the vscode-java-test Wiki.

View test results

After running/debugging the test cases, the state of the related test items will be updated in both editor decorations and the Testing Explorer.

You can trigger the command Test: Peek Output to peek the results view. You can select the links in the stack trace to navigate to the source location.

Generate tests

The extension provides features to help you scaffold test cases. You can find the entry in the editor context menu. Select Source Action... and then choose Generate Tests....

If you trigger this source action from your main source code (test subject), you will be asked the test class's fully qualified name and the methods you want to test. The extension will then generate the test code for you:

If you trigger the source action from your test source code, you will be asked which kinds of test methods you want to add. Including the lifecycle methods and the test method:

Test navigation

The extension provides features to help you navigate between your tests and test subjects. If your source code is contained in src/main/java or src/test/java, you can find the entry named Go to Test or Go to Test Subject in the editor context menu:

You can also find the command in the Command Palette (⇧⌘P (Windows, Linux Ctrl+Shift+P)) by searching for Java: Go to Test.

VS Code testing commands

There are other testing commands (for example, Run Tests in Current File) that can be found by searching for 'Test:' in the Command Palette (⇧⌘P (Windows, Linux Ctrl+Shift+P)).

Testing commands in the Command Palette

VS Code testing settings

There are VS Code settings specific to testing that can be found by searching for 'testing' in the Settings editor (⌘, (Windows, Linux Ctrl+,)).

Testing settings in the Settings editor

FAQ

If you meet any problem when using the extension, you can review the FAQ and our issue list to check if there is an answer to your problem.

Contributing and feedback

If you are interested in providing feedback or contributing directly to the code base, please read Contributing to Test Runner for Java, which covers the following:

Next steps

Read on to find out about:

  • Debugging - Find out how to debug your Java project with VS Code.
  • Extensions for Java - Learn about more useful Java extensions for VS Code.
2/11/2022