In the Package Explorer view, right-click on the file that you would like to create a JUnit test for. In the opened context menu, select New -> Other… . In the Select a wizard dialog, select Java -> JUnit -> JUnit Test Case .
Then a dialog opens. In case you have a default Maven or Gradle project, you will probably have to change the default Source folder from the provided ${PROJECT_NAME}/src/main/java to ${PROJECT_NAME}/src/test/java. If you click Next, the dialog allows you to check which methods to automatically create stubs for.