NoSuchMethodError: java.util.Set org.junit.platform.engine.TestDescriptor.getAncestors() is an error that can occur when using Eclipse and Gradle. It is caused by a missing dependency in the build.gradle file.
The solution is to add the following dependency to the dependencies section of the build.gradle file:
testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
This dependency provides the necessary classes and methods for running JUnit tests in Eclipse.
Another possible cause of this error is a missing dependency on the junit-jupiter library. This dependency can be added to the pom.xml file as follows:
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter</artifactId>
<version>5.8.2</version>
<scope>test</scope>
</dependency>
Once the necessary dependencies have been added, the error should be resolved.
If you are still experiencing the error, you may need to update your version of Eclipse or Gradle. You can also try cleaning and rebuilding your project.