                                   failAction: (String) -> Void,
                                   readFile: (String) -> String) -> [SwiftLintViolation] {
 
+        let files = files.filter { $0.fileType == .swift }
+        
         // Only run Swiftlint, if there are files to lint
         guard !files.isEmpty else {
             return []

/// it usable out of the box.
public enum SwiftLint {
    public enum LintStyle {
        case all(directory: String?)
        case modifiedAndCreatedFiles(directory: String?)
        case files([File])
    }


                                 readFile: readFile)
        case .modifiedAndCreatedFiles(let directory):
            // Gathers modified+created files, invokes SwiftLint on each, and posts collected errors+warnings to Danger.
            var files = (danger.git.createdFiles + danger.git.modifiedFiles)
            if let directory = directory {
                files = files.filter { $0.hasPrefix(directory) }
            }
