Get tests specified by '--tests' commandline argument

Thanks for detailed explanation. I was not aware that there is a difference in running directly from gradle and invoking it via IDEA.
So something like this code solved my problem

tasks.withType(Test) {
    doFirst {
        def result = filter.commandLineIncludePatterns ? filter.commandLineIncludePatterns[0] :
                filter.includePatterns ? filter.includePatterns[0] : "UI tests"
        result = result.replace("*", "")
        systemProperty "testsFilter", result
    }
}

Thanks for help!