mirror of https://github.com/golang/go.git
testing/iotest: add TestReader to test readers
There are many reader behaviors that are subtle and worth testing, and it's nice to have one complete tester instead of many incomplete ones. For #41190, which will use this as part of a larger file system implementation tester. Change-Id: Ib4cc7fae94b0d9b45dfacadc52baa77ad3761322 Reviewed-on: https://go-review.googlesource.com/c/go/+/243909 Trust: Russ Cox <rsc@golang.org> Run-TryBot: Russ Cox <rsc@golang.org> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Rob Pike <r@golang.org> Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
This commit is contained in:
Russ Cox
parent
7bb721b938
commit
9ad090c5fe
|
|
@ -6,8 +6,11 @@
|
|||
package iotest
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"errors"
|
||||
"fmt"
|
||||
"io"
|
||||
"io/ioutil"
|
||||
)
|
||||
|
||||
// OneByteReader returns a Reader that implements
|
||||
|
|
@ -90,13 +93,177 @@ func (r *timeoutReader) Read(p []byte) (int, error) {
|
|||
|
||||
// ErrReader returns an io.Reader that returns 0, err from all Read calls.
|
||||
func ErrReader(err error) io.Reader {
|
||||
return &alwaysErrReader{err: err}
|
||||
return &errReader{err: err}
|
||||
}
|
||||
|
||||
type alwaysErrReader struct {
|
||||
type errReader struct {
|
||||
err error
|
||||
}
|
||||
|
||||
func (aer *alwaysErrReader) Read(p []byte) (int, error) {
|
||||
return 0, aer.err
|
||||
func (r *errReader) Read(p []byte) (int, error) {
|
||||
return 0, r.err
|
||||
}
|
||||
|
||||
type smallByteReader struct {
|
||||
r io.Reader
|
||||
off int
|
||||
n int
|
||||
}
|
||||
|
||||
func (r *smallByteReader) Read(p []byte) (int, error) {
|
||||
if len(p) == 0 {
|
||||
return 0, nil
|
||||
}
|
||||
r.n = r.n%3 + 1
|
||||
n := r.n
|
||||
if n > len(p) {
|
||||
n = len(p)
|
||||
}
|
||||
n, err := r.r.Read(p[0:n])
|
||||
if err != nil && err != io.EOF {
|
||||
err = fmt.Errorf("Read(%d bytes at offset %d): %v", n, r.off, err)
|
||||
}
|
||||
r.off += n
|
||||
return n, err
|
||||
}
|
||||
|
||||
// TestReader tests that reading from r returns the expected file content.
|
||||
// It does reads of different sizes, until EOF.
|
||||
// If r implements io.ReaderAt or io.Seeker, TestReader also checks
|
||||
// that those operations behave as they should.
|
||||
//
|
||||
// If TestReader finds any misbehaviors, it returns an error reporting them.
|
||||
// The error text may span multiple lines.
|
||||
func TestReader(r io.Reader, content []byte) error {
|
||||
if len(content) > 0 {
|
||||
n, err := r.Read(nil)
|
||||
if n != 0 || err != nil {
|
||||
return fmt.Errorf("Read(0) = %d, %v, want 0, nil", n, err)
|
||||
}
|
||||
}
|
||||
|
||||
data, err := ioutil.ReadAll(&smallByteReader{r: r})
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
if !bytes.Equal(data, content) {
|
||||
return fmt.Errorf("ReadAll(small amounts) = %q\n\twant %q", data, content)
|
||||
}
|
||||
n, err := r.Read(make([]byte, 10))
|
||||
if n != 0 || err != io.EOF {
|
||||
return fmt.Errorf("Read(10) at EOF = %v, %v, want 0, EOF", n, err)
|
||||
}
|
||||
|
||||
if r, ok := r.(io.ReadSeeker); ok {
|
||||
// Seek(0, 1) should report the current file position (EOF).
|
||||
if off, err := r.Seek(0, 1); off != int64(len(content)) || err != nil {
|
||||
return fmt.Errorf("Seek(0, 1) from EOF = %d, %v, want %d, nil", off, err, len(content))
|
||||
}
|
||||
|
||||
// Seek backward partway through file, in two steps.
|
||||
// If middle == 0, len(content) == 0, can't use the -1 and +1 seeks.
|
||||
middle := len(content) - len(content)/3
|
||||
if middle > 0 {
|
||||
if off, err := r.Seek(-1, 1); off != int64(len(content)-1) || err != nil {
|
||||
return fmt.Errorf("Seek(-1, 1) from EOF = %d, %v, want %d, nil", -off, err, len(content)-1)
|
||||
}
|
||||
if off, err := r.Seek(int64(-len(content)/3), 1); off != int64(middle-1) || err != nil {
|
||||
return fmt.Errorf("Seek(%d, 1) from %d = %d, %v, want %d, nil", -len(content)/3, len(content)-1, off, err, middle-1)
|
||||
}
|
||||
if off, err := r.Seek(+1, 1); off != int64(middle) || err != nil {
|
||||
return fmt.Errorf("Seek(+1, 1) from %d = %d, %v, want %d, nil", middle-1, off, err, middle)
|
||||
}
|
||||
}
|
||||
|
||||
// Seek(0, 1) should report the current file position (middle).
|
||||
if off, err := r.Seek(0, 1); off != int64(middle) || err != nil {
|
||||
return fmt.Errorf("Seek(0, 1) from %d = %d, %v, want %d, nil", middle, off, err, middle)
|
||||
}
|
||||
|
||||
// Reading forward should return the last part of the file.
|
||||
data, err := ioutil.ReadAll(&smallByteReader{r: r})
|
||||
if err != nil {
|
||||
return fmt.Errorf("ReadAll from offset %d: %v", middle, err)
|
||||
}
|
||||
if !bytes.Equal(data, content[middle:]) {
|
||||
return fmt.Errorf("ReadAll from offset %d = %q\n\twant %q", middle, data, content[middle:])
|
||||
}
|
||||
|
||||
// Seek relative to end of file, but start elsewhere.
|
||||
if off, err := r.Seek(int64(middle/2), 0); off != int64(middle/2) || err != nil {
|
||||
return fmt.Errorf("Seek(%d, 0) from EOF = %d, %v, want %d, nil", middle/2, off, err, middle/2)
|
||||
}
|
||||
if off, err := r.Seek(int64(-len(content)/3), 2); off != int64(middle) || err != nil {
|
||||
return fmt.Errorf("Seek(%d, 2) from %d = %d, %v, want %d, nil", -len(content)/3, middle/2, off, err, middle)
|
||||
}
|
||||
|
||||
// Reading forward should return the last part of the file (again).
|
||||
data, err = ioutil.ReadAll(&smallByteReader{r: r})
|
||||
if err != nil {
|
||||
return fmt.Errorf("ReadAll from offset %d: %v", middle, err)
|
||||
}
|
||||
if !bytes.Equal(data, content[middle:]) {
|
||||
return fmt.Errorf("ReadAll from offset %d = %q\n\twant %q", middle, data, content[middle:])
|
||||
}
|
||||
|
||||
// Absolute seek & read forward.
|
||||
if off, err := r.Seek(int64(middle/2), 0); off != int64(middle/2) || err != nil {
|
||||
return fmt.Errorf("Seek(%d, 0) from EOF = %d, %v, want %d, nil", middle/2, off, err, middle/2)
|
||||
}
|
||||
data, err = ioutil.ReadAll(r)
|
||||
if err != nil {
|
||||
return fmt.Errorf("ReadAll from offset %d: %v", middle/2, err)
|
||||
}
|
||||
if !bytes.Equal(data, content[middle/2:]) {
|
||||
return fmt.Errorf("ReadAll from offset %d = %q\n\twant %q", middle/2, data, content[middle/2:])
|
||||
}
|
||||
}
|
||||
|
||||
if r, ok := r.(io.ReaderAt); ok {
|
||||
data := make([]byte, len(content), len(content)+1)
|
||||
for i := range data {
|
||||
data[i] = 0xfe
|
||||
}
|
||||
n, err := r.ReadAt(data, 0)
|
||||
if n != len(data) || err != nil && err != io.EOF {
|
||||
return fmt.Errorf("ReadAt(%d, 0) = %v, %v, want %d, nil or EOF", len(data), n, err, len(data))
|
||||
}
|
||||
if !bytes.Equal(data, content) {
|
||||
return fmt.Errorf("ReadAt(%d, 0) = %q\n\twant %q", len(data), data, content)
|
||||
}
|
||||
|
||||
n, err = r.ReadAt(data[:1], int64(len(data)))
|
||||
if n != 0 || err != io.EOF {
|
||||
return fmt.Errorf("ReadAt(1, %d) = %v, %v, want 0, EOF", len(data), n, err)
|
||||
}
|
||||
|
||||
for i := range data {
|
||||
data[i] = 0xfe
|
||||
}
|
||||
n, err = r.ReadAt(data[:cap(data)], 0)
|
||||
if n != len(data) || err != io.EOF {
|
||||
return fmt.Errorf("ReadAt(%d, 0) = %v, %v, want %d, EOF", cap(data), n, err, len(data))
|
||||
}
|
||||
if !bytes.Equal(data, content) {
|
||||
return fmt.Errorf("ReadAt(%d, 0) = %q\n\twant %q", len(data), data, content)
|
||||
}
|
||||
|
||||
for i := range data {
|
||||
data[i] = 0xfe
|
||||
}
|
||||
for i := range data {
|
||||
n, err = r.ReadAt(data[i:i+1], int64(i))
|
||||
if n != 1 || err != nil && (i != len(data)-1 || err != io.EOF) {
|
||||
want := "nil"
|
||||
if i == len(data)-1 {
|
||||
want = "nil or EOF"
|
||||
}
|
||||
return fmt.Errorf("ReadAt(1, %d) = %v, %v, want 1, %s", i, n, err, want)
|
||||
}
|
||||
if data[i] != content[i] {
|
||||
return fmt.Errorf("ReadAt(1, %d) = %q want %q", i, data[i:i+1], content[i:i+1])
|
||||
}
|
||||
}
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
|
|
|||
|
|
@ -8,6 +8,7 @@ import (
|
|||
"bytes"
|
||||
"errors"
|
||||
"io"
|
||||
"strings"
|
||||
"testing"
|
||||
)
|
||||
|
||||
|
|
@ -249,3 +250,12 @@ func TestErrReader(t *testing.T) {
|
|||
})
|
||||
}
|
||||
}
|
||||
|
||||
func TestStringsReader(t *testing.T) {
|
||||
const msg = "Now is the time for all good gophers."
|
||||
|
||||
r := strings.NewReader(msg)
|
||||
if err := TestReader(r, []byte(msg)); err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue