1. Create a Maven project with groovy, spock and junit.
2. Create a spock test case with def variable = new ....() {} declaration ({} is the key here). For example,

class MySpec extends Specification {
    def list = new ArrayList() {
    }

    def "..."() {
...
    }
}

3. Run all tests in a package/directory

Eclipse shows "No tests found with test runner 'JUnit 4'.

test-project.zip

Maven build succeeds.