func (covList CoverageList) ListDirectories() []string {
	dirSet := map[string]bool{}
	for _, cov := range covList.Group {
		dirSet[path.Dir(cov.Name)] = true
	}
	var result []string
	for key := range dirSet {
		result = append(result, key)
	}
	return result
}
func (covList CoverageList) ListDirectories() []string {
	dirSet := map[string]bool{}
	for _, cov := range covList.Group {
		dirSet[path.Dir(cov.Name)] = true
	}
	var result []string
	for key := range dirSet {
		result = append(result, key)
	}
	return result
}
// ListDirectories gets a list a sub-directories that contains source code.