### Question:
PathUtil { public static boolean existAll( File... files ) { if ( files == null ) { return false; } if ( files.length == 0 ) { return false; } for ( File file : files ) { if ( !file.exists() ) { return false; } } return true; } private  PathUtil(); static boolean existAll( File... files ); static boolean existAll( List<String> paths ); static boolean existAny( File... files ); static File[] existingFiles( Collection<String> paths ); static File[] existingFiles( File... files ); static List<File> existingFilesList( Collection<String> paths ); static List<File> existingFilesList( List<File> files ); static File file( File file ); static File file( String path ); static File file( String path, File basedir ); static File file( String path, File... basedirs ); static File file( String path, List<File> basedirs ); static File file( String path, String basedir ); static String fileExtention( File file ); static File[] files( Collection<String> paths ); static Collection<File> files( List<String> paths, File basedir ); static File[] files( String... paths ); static Collection<File> files( String[] paths, File basedir ); static File[] files( String[] paths, List<File> basedirs ); static List<File> filesList( Collection<String> paths ); static String path( File file ); static String[] paths( Collection<File> files ); static String[] paths( File... files ); static List<String> pathsList( File[] files ); static List<String> pathsList( List<File> files ); static String pathString( File[] files ); static String relativePath( File home, File f );  }### Answer:
@Test public void testExistAllFileArray() { assertThat( PathUtil.existAll(), equalTo( false ) ); assertThat( PathUtil.existAll( (File[]) null ), equalTo( false ) ); assertThat( PathUtil.existAll( f1 ), equalTo( true ) ); assertThat( PathUtil.existAll( f2 ), equalTo( false ) ); assertThat( PathUtil.existAll( f1, f3 ), equalTo( true ) ); assertThat( PathUtil.existAll( f1, f2, f4 ), equalTo( false ) ); }
@Test public void testExistAllListOfString() { assertThat( PathUtil.existAll( (List<String>) null ), equalTo( false ) ); assertThat( PathUtil.existAll( Arrays.asList( f5.getAbsolutePath() ) ), equalTo( true ) ); }