NopCloser returns a ReadCloser with a no-op Close method wrapping the provided Reader r.

ReadAll reads from r until an error or EOF and returns the data it read.

ReadDir reads the directory named by dirname and returns a list of sorted directory entries.

ReadFile reads the file named by filename and returns the contents.

TempDir creates a new temporary directory in the directory dir with a name beginning with prefix and returns the path of the new directory.

TempFile creates a new temporary file in the directory dir with a name beginning with prefix, opens the file for reading and writing, and returns the resulting *os.File.

WriteFile writes data to a file named by filename.

Discard is an io.Writer on which all Write calls succeed without doing anything.