refactor: move dialer's errorwrapper in i/errorsx (#417)

Part of https://github.com/ooni/probe/issues/1505

internal/engine/netx/dialer/dialer.go

@@ -6,6 +6,7 @@ import (
 	"net/url"
 
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/trace"
+	"github.com/ooni/probe-cli/v3/internal/errorsx"
 	"github.com/ooni/probe-cli/v3/internal/netxlite"
 )
 
@@ -69,7 +70,7 @@ type Config struct {
 // New creates a new Dialer from the specified config and resolver.
 func New(config *Config, resolver Resolver) Dialer {
 	var d Dialer = netxlite.DefaultDialer
-	d = &errorWrapperDialer{Dialer: d}
+	d = &errorsx.ErrorWrapperDialer{Dialer: d}
 	if config.Logger != nil {
 		d = &netxlite.DialerLogger{Dialer: d, Logger: config.Logger}
 	}

internal/engine/netx/dialer/dialer_test.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/apex/log"
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/trace"
+	"github.com/ooni/probe-cli/v3/internal/errorsx"
 	"github.com/ooni/probe-cli/v3/internal/netxlite"
 )
 
@@ -47,7 +48,7 @@ func TestNewCreatesTheExpectedChain(t *testing.T) {
 	if !ok {
 		t.Fatal("not a loggingDialer")
 	}
-	ewd, ok := ld.Dialer.(*errorWrapperDialer)
+	ewd, ok := ld.Dialer.(*errorsx.ErrorWrapperDialer)
 	if !ok {
 		t.Fatal("not an errorWrappingDialer")
 	}

internal/errorsx/dialer.go

@@ -1,23 +1,27 @@
-package dialer
+package errorsx
 
 import (
 	"context"
 	"net"
-
-	"github.com/ooni/probe-cli/v3/internal/errorsx"
 )
 
-// errorWrapperDialer is a dialer that performs err wrapping
+// Dialer establishes network connections.
-type errorWrapperDialer struct {
+type Dialer interface {
+	// DialContext behaves like net.Dialer.DialContext.
+	DialContext(ctx context.Context, network, address string) (net.Conn, error)
+}
+
+// ErrorWrapperDialer is a dialer that performs err wrapping.
+type ErrorWrapperDialer struct {
 	Dialer
 }
 
 // DialContext implements Dialer.DialContext
-func (d *errorWrapperDialer) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
+func (d *ErrorWrapperDialer) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
 	conn, err := d.Dialer.DialContext(ctx, network, address)
-	err = errorsx.SafeErrWrapperBuilder{
+	err = SafeErrWrapperBuilder{
 		Error:     err,
-		Operation: errorsx.ConnectOperation,
+		Operation: ConnectOperation,
 	}.MaybeBuild()
 	if err != nil {
 		return nil, err
@@ -33,9 +37,9 @@ type errorWrapperConn struct {
 // Read implements net.Conn.Read
 func (c *errorWrapperConn) Read(b []byte) (n int, err error) {
 	n, err = c.Conn.Read(b)
-	err = errorsx.SafeErrWrapperBuilder{
+	err = SafeErrWrapperBuilder{
 		Error:     err,
-		Operation: errorsx.ReadOperation,
+		Operation: ReadOperation,
 	}.MaybeBuild()
 	return
 }
@@ -43,9 +47,9 @@ func (c *errorWrapperConn) Read(b []byte) (n int, err error) {
 // Write implements net.Conn.Write
 func (c *errorWrapperConn) Write(b []byte) (n int, err error) {
 	n, err = c.Conn.Write(b)
-	err = errorsx.SafeErrWrapperBuilder{
+	err = SafeErrWrapperBuilder{
 		Error:     err,
-		Operation: errorsx.WriteOperation,
+		Operation: WriteOperation,
 	}.MaybeBuild()
 	return
 }
@@ -53,9 +57,9 @@ func (c *errorWrapperConn) Write(b []byte) (n int, err error) {
 // Close implements net.Conn.Close
 func (c *errorWrapperConn) Close() (err error) {
 	err = c.Conn.Close()
-	err = errorsx.SafeErrWrapperBuilder{
+	err = SafeErrWrapperBuilder{
 		Error:     err,
-		Operation: errorsx.CloseOperation,
+		Operation: CloseOperation,
 	}.MaybeBuild()
 	return
 }

internal/errorsx/dialer_test.go

@@ -1,4 +1,4 @@
-package dialer
+package errorsx
 
 import (
 	"context"
@@ -7,13 +7,12 @@ import (
 	"net"
 	"testing"
 
-	"github.com/ooni/probe-cli/v3/internal/errorsx"
 	"github.com/ooni/probe-cli/v3/internal/netxmocks"
 )
 
 func TestErrorWrapperFailure(t *testing.T) {
 	ctx := context.Background()
-	d := &errorWrapperDialer{Dialer: &netxmocks.Dialer{
+	d := &ErrorWrapperDialer{Dialer: &netxmocks.Dialer{
 		MockDialContext: func(ctx context.Context, network string, address string) (net.Conn, error) {
 			return nil, io.EOF
 		},
@@ -22,28 +21,28 @@ func TestErrorWrapperFailure(t *testing.T) {
 	if conn != nil {
 		t.Fatal("expected a nil conn here")
 	}
-	errorWrapperCheckErr(t, err, errorsx.ConnectOperation)
+	errorWrapperCheckErr(t, err, ConnectOperation)
 }
 
 func errorWrapperCheckErr(t *testing.T, err error, op string) {
 	if !errors.Is(err, io.EOF) {
 		t.Fatal("expected another error here")
 	}
-	var errWrapper *errorsx.ErrWrapper
+	var errWrapper *ErrWrapper
 	if !errors.As(err, &errWrapper) {
 		t.Fatal("cannot cast to ErrWrapper")
 	}
 	if errWrapper.Operation != op {
 		t.Fatal("unexpected Operation")
 	}
-	if errWrapper.Failure != errorsx.FailureEOFError {
+	if errWrapper.Failure != FailureEOFError {
 		t.Fatal("unexpected failure")
 	}
 }
 
 func TestErrorWrapperSuccess(t *testing.T) {
 	ctx := context.Background()
-	d := &errorWrapperDialer{Dialer: &netxmocks.Dialer{
+	d := &ErrorWrapperDialer{Dialer: &netxmocks.Dialer{
 		MockDialContext: func(ctx context.Context, network string, address string) (net.Conn, error) {
 			return &netxmocks.Conn{
 				MockRead: func(b []byte) (int, error) {
@@ -69,11 +68,11 @@ func TestErrorWrapperSuccess(t *testing.T) {
 		t.Fatal("expected non-nil conn here")
 	}
 	count, err := conn.Read(nil)
-	errorWrapperCheckIOResult(t, count, err, errorsx.ReadOperation)
+	errorWrapperCheckIOResult(t, count, err, ReadOperation)
 	count, err = conn.Write(nil)
-	errorWrapperCheckIOResult(t, count, err, errorsx.WriteOperation)
+	errorWrapperCheckIOResult(t, count, err, WriteOperation)
 	err = conn.Close()
-	errorWrapperCheckErr(t, err, errorsx.CloseOperation)
+	errorWrapperCheckErr(t, err, CloseOperation)
 }
 
 func errorWrapperCheckIOResult(t *testing.T, count int, err error, op string) {