var ErrTimeout =errors.New("timeout")

funcDataErrReader¶

func DataErrReader(rio.Reader)io.Reader

DataErrReader changes the way errors are handled by a Reader. Normally, aReader returns an error (typically EOF) from the first Read call after thelast piece of data is read. DataErrReader wraps a Reader and changes itsbehavior so the final error is returned along with the final data, insteadof in the first call after the final data.

funcErrReader¶added ingo1.16

func ErrReader(errerror)io.Reader

ErrReader returns anio.Reader that returns 0, err from all Read calls.

package mainimport ("errors""fmt""testing/iotest")func main() {// A reader that always returns a custom error.r := iotest.ErrReader(errors.New("custom error"))n, err := r.Read(nil)fmt.Printf("n:   %d\nerr: %q\n", n, err)}

Output:n:   0err: "custom error"

funcHalfReader¶

func HalfReader(rio.Reader)io.Reader

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

funcNewReadLogger¶

func NewReadLogger(prefixstring, rio.Reader)io.Reader

NewReadLogger returns a reader that behaves like r exceptthat it logs (usinglog.Printf) each read to standard error,printing the prefix and the hexadecimal data read.

funcNewWriteLogger¶

func NewWriteLogger(prefixstring, wio.Writer)io.Writer

NewWriteLogger returns a writer that behaves like w exceptthat it logs (usinglog.Printf) each write to standard error,printing the prefix and the hexadecimal data written.

funcOneByteReader¶

func OneByteReader(rio.Reader)io.Reader

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

funcTestReader¶added ingo1.16

func TestReader(rio.Reader, content []byte)error

TestReader tests that reading from r returns the expected file content.It does reads of different sizes, until EOF.If r implementsio.ReaderAt orio.Seeker, TestReader also checksthat those operations behave as they should.

If TestReader finds any misbehaviors, it returns an error reporting them.The error text may span multiple lines.

funcTimeoutReader¶

func TimeoutReader(rio.Reader)io.Reader

TimeoutReader returnsErrTimeout on the second readwith no data. Subsequent calls to read succeed.

funcTruncateWriter¶

func TruncateWriter(wio.Writer, nint64)io.Writer

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