void expectFiles(String... fileNames) {
        expectFiles(fileNames as List<String>)
    }

    void expectFiles(List<String> fileNames) {
        expectedFileNames = fileNames.sort()
    }

    void noFiles() {
        expectedFileNames = []
    }

    void shouldFail(@DelegatesTo(value = ExecutionFailure, strategy = Closure.DELEGATE_FIRST) Closure<?> onFailure) {
        expectSuccess = false