DataErrReader changes the way errors are handled by a Reader.

ErrReader returns an [io.Reader] that returns 0, err from all Read calls.

HalfReader returns a Reader that implements Read by reading half as many requested bytes from r.

NewReadLogger returns a reader that behaves like r except that it logs (using [log.Printf]) each read to standard error, printing the prefix and the hexadecimal data read.

NewWriteLogger returns a writer that behaves like w except that it logs (using [log.Printf]) each write to standard error, printing the prefix and the hexadecimal data written.

OneByteReader returns a Reader that implements each non-empty Read by reading one byte from r.

TestReader tests that reading from r returns the expected file content.

TimeoutReader returns [ErrTimeout] on the second read with no data.

TruncateWriter returns a Writer that writes to w but stops silently after n bytes.

ErrTimeout is a fake timeout error.