Lint and documentation fixes

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

registry/client/blob_writer_test.go

@@ -152,7 +152,7 @@ func TestUploadReadFrom(t *testing.T) {
 		t.Fatalf("Expected error when not found")
 	}
 	if err != distribution.ErrBlobUploadUnknown {
-		t.Fatalf("Wrong error thrown: %s, expected", err, distribution.ErrBlobUploadUnknown)
+		t.Fatalf("Wrong error thrown: %s, expected %s", err, distribution.ErrBlobUploadUnknown)
 	}
 
 	// 400 valid json

registry/client/transport/http_reader.go

@@ -13,6 +13,9 @@ import (
 	"github.com/docker/distribution"
 )
 
+// NewHTTPReadSeeker handles reading from an HTTP endpoint using a GET
+// request. When seeking and starting a read from a non-zero offset
+// the a "Range" header will be added which sets the offset.
 func NewHTTPReadSeeker(client *http.Client, url string, size int64) distribution.ReadSeekCloser {
 	return &httpReadSeeker{
 		client: client,

registry/client/transport/transport.go

@@ -6,12 +6,16 @@ import (
 	"sync"
 )
 
+// RequestModifier represents an object which will do an inplace
+// modification of an HTTP request.
 type RequestModifier interface {
 	ModifyRequest(*http.Request) error
 }
 
 type headerModifier http.Header
 
+// NewHeaderRequestModifier returns a new RequestModifier which will
+// add the given headers to a request.
 func NewHeaderRequestModifier(header http.Header) RequestModifier {
 	return headerModifier(header)
 }
@@ -24,6 +28,8 @@ func (h headerModifier) ModifyRequest(req *http.Request) error {
 	return nil
 }
 
+// NewTransport creates a new transport which will apply modifiers to
+// the request on a RoundTrip call.
 func NewTransport(base http.RoundTripper, modifiers ...RequestModifier) http.RoundTripper {
 	return &transport{
 		Modifiers: modifiers,