A Tour of Go Exercise: Readers
こんな感じ
package main import "golang.org/x/tour/reader" type MyReader struct{} // TODO: Add a Read([]byte) (int, error) method to MyReader. func (r MyReader) Read(b []byte) (int, error) { for i := 0; i < len(b); i++ { b[i] = 'A' } return len(b), nil } func main() { reader.Validate(MyReader{}) }