lib/readers: factor ErrorReader from multiple sources

backend/crypt/cipher_test.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/pkg/errors"
 	"github.com/rclone/rclone/backend/crypt/pkcs7"
+	"github.com/rclone/rclone/lib/readers"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -784,7 +785,7 @@ func TestNewEncrypterErrUnexpectedEOF(t *testing.T) {
 	c, err := newCipher(NameEncryptionStandard, "", "", true)
 	assert.NoError(t, err)
 
-	in := &errorReader{io.ErrUnexpectedEOF}
+	in := &readers.ErrorReader{Err: io.ErrUnexpectedEOF}
 	fh, err := c.newEncrypter(in, nil)
 	assert.NoError(t, err)
 
@@ -793,14 +794,6 @@ func TestNewEncrypterErrUnexpectedEOF(t *testing.T) {
 	assert.Equal(t, int64(32), n)
 }
 
-type errorReader struct {
-	err error
-}
-
-func (er errorReader) Read(p []byte) (n int, err error) {
-	return 0, er.err
-}
-
 type closeDetector struct {
 	io.Reader
 	closed int
@@ -838,7 +831,7 @@ func TestNewDecrypter(t *testing.T) {
 		assert.Equal(t, 1, cd.closed)
 	}
 
-	er := &errorReader{errors.New("potato")}
+	er := &readers.ErrorReader{Err: errors.New("potato")}
 	cd = newCloseDetector(er)
 	fh, err = c.newDecrypter(cd)
 	assert.Nil(t, fh)
@@ -864,7 +857,7 @@ func TestNewDecrypterErrUnexpectedEOF(t *testing.T) {
 	c, err := newCipher(NameEncryptionStandard, "", "", true)
 	assert.NoError(t, err)
 
-	in2 := &errorReader{io.ErrUnexpectedEOF}
+	in2 := &readers.ErrorReader{Err: io.ErrUnexpectedEOF}
 	in1 := bytes.NewBuffer(file16)
 	in := ioutil.NopCloser(io.MultiReader(in1, in2))
 
@@ -1118,7 +1111,7 @@ func TestDecrypterRead(t *testing.T) {
 
 	// Test producing an error on the file on Read the underlying file
 	in1 := bytes.NewBuffer(file1)
-	in2 := &errorReader{errors.New("potato")}
+	in2 := &readers.ErrorReader{Err: errors.New("potato")}
 	in := io.MultiReader(in1, in2)
 	cd := newCloseDetector(in)
 	fh, err := c.newDecrypter(cd)

fs/operations/operations_test.go

@@ -45,6 +45,7 @@ import (
 	"github.com/rclone/rclone/fs/operations"
 	"github.com/rclone/rclone/fstest"
 	"github.com/rclone/rclone/lib/random"
+	"github.com/rclone/rclone/lib/readers"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -1156,14 +1157,6 @@ func TestOverlapping(t *testing.T) {
 	}
 }
 
-type errorReader struct {
-	err error
-}
-
-func (er errorReader) Read(p []byte) (n int, err error) {
-	return 0, er.err
-}
-
 func TestCheckEqualReaders(t *testing.T) {
 	b65a := make([]byte, 65*1024)
 	b65b := make([]byte, 65*1024)
@@ -1189,7 +1182,7 @@ func TestCheckEqualReaders(t *testing.T) {
 	myErr := errors.New("sentinel")
 	wrap := func(b []byte) io.Reader {
 		r := bytes.NewBuffer(b)
-		e := errorReader{myErr}
+		e := readers.ErrorReader{Err: myErr}
 		return io.MultiReader(r, e)
 	}
 

fs/operations/reopen_test.go

@@ -10,6 +10,7 @@ import (
 	"github.com/rclone/rclone/fs"
 	"github.com/rclone/rclone/fs/hash"
 	"github.com/rclone/rclone/fstest/mockobject"
+	"github.com/rclone/rclone/lib/readers"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -44,23 +45,13 @@ func (o *reOpenTestObject) Open(ctx context.Context, options ...fs.OpenOption) (
 			return nil, errorTestError
 		}
 		// Read N bytes then an error
-		r := io.MultiReader(&io.LimitedReader{R: rc, N: N}, errorReader{errorTestError})
+		r := io.MultiReader(&io.LimitedReader{R: rc, N: N}, readers.ErrorReader{Err: errorTestError})
 		// Wrap with Close in a new readCloser
 		rc = readCloser{Reader: r, Closer: rc}
 	}
 	return rc, nil
 }
 
-// Return an error only
-type errorReader struct {
-	err error
-}
-
-// Read returning an error
-func (er errorReader) Read(p []byte) (n int, err error) {
-	return 0, er.err
-}
-
 func TestReOpen(t *testing.T) {
 	for testIndex, testName := range []string{"Seek", "Range"} {
 		t.Run(testName, func(t *testing.T) {

fstest/fstests/fstests.go

@@ -225,16 +225,6 @@ func TestPutLarge(ctx context.Context, t *testing.T, f fs.Fs, file *fstest.Item)
 	require.NoError(t, obj.Remove(ctx))
 }
 
-// errorReader just returns an error on Read
-type errorReader struct {
-	err error
-}
-
-// Read returns an error immediately
-func (er errorReader) Read(p []byte) (n int, err error) {
-	return 0, er.err
-}
-
 // read the contents of an object as a string
 func readObject(ctx context.Context, t *testing.T, obj fs.Object, limit int64, options ...fs.OpenOption) string {
 	what := fmt.Sprintf("readObject(%q) limit=%d, options=%+v", obj, limit, options)
@@ -637,7 +627,7 @@ func Run(t *testing.T, opt *Opt) {
 			// Read N bytes then produce an error
 			contents := random.String(int(N))
 			buf := bytes.NewBufferString(contents)
-			er := &errorReader{errors.New("potato")}
+			er := &readers.ErrorReader{Err: errors.New("potato")}
 			in := io.MultiReader(buf, er)
 
 			obji := object.NewStaticObjectInfo(file2.Path, file2.ModTime, 2*N, true, nil, nil)

lib/readers/error.go

@@ -0,0 +1,11 @@
+package readers
+
+// ErrorReader wraps an error to return on Read
+type ErrorReader struct {
+	Err error
+}
+
+// Read always returns the error
+func (er ErrorReader) Read(p []byte) (n int, err error) {
+	return 0, er.Err
+}

lib/readers/error_test.go

@@ -0,0 +1,18 @@
+package readers
+
+import (
+	"testing"
+
+	"github.com/pkg/errors"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestErrorReader(t *testing.T) {
+	errRead := errors.New("boom")
+	r := ErrorReader{errRead}
+
+	buf := make([]byte, 16)
+	n, err := r.Read(buf)
+	assert.Equal(t, errRead, err)
+	assert.Equal(t, 0, n)
+}