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

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

internal/engine/netx/dialer/errorwrapper_test.go

@@ -1,84 +0,0 @@
-package dialer
-
-import (
-	"context"
-	"errors"
-	"io"
-	"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{
-		MockDialContext: func(ctx context.Context, network string, address string) (net.Conn, error) {
-			return nil, io.EOF
-		},
-	}}
-	conn, err := d.DialContext(ctx, "tcp", "www.google.com:443")
-	if conn != nil {
-		t.Fatal("expected a nil conn here")
-	}
-	errorWrapperCheckErr(t, err, errorsx.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
-	if !errors.As(err, &errWrapper) {
-		t.Fatal("cannot cast to ErrWrapper")
-	}
-	if errWrapper.Operation != op {
-		t.Fatal("unexpected Operation")
-	}
-	if errWrapper.Failure != errorsx.FailureEOFError {
-		t.Fatal("unexpected failure")
-	}
-}
-
-func TestErrorWrapperSuccess(t *testing.T) {
-	ctx := context.Background()
-	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) {
-					return 0, io.EOF
-				},
-				MockWrite: func(b []byte) (int, error) {
-					return 0, io.EOF
-				},
-				MockClose: func() error {
-					return io.EOF
-				},
-				MockLocalAddr: func() net.Addr {
-					return &net.TCPAddr{Port: 12345}
-				},
-			}, nil
-		},
-	}}
-	conn, err := d.DialContext(ctx, "tcp", "www.google.com")
-	if err != nil {
-		t.Fatal(err)
-	}
-	if conn == nil {
-		t.Fatal("expected non-nil conn here")
-	}
-	count, err := conn.Read(nil)
-	errorWrapperCheckIOResult(t, count, err, errorsx.ReadOperation)
-	count, err = conn.Write(nil)
-	errorWrapperCheckIOResult(t, count, err, errorsx.WriteOperation)
-	err = conn.Close()
-	errorWrapperCheckErr(t, err, errorsx.CloseOperation)
-}
-
-func errorWrapperCheckIOResult(t *testing.T, count int, err error, op string) {
-	if count != 0 {
-		t.Fatal("expected nil count here")
-	}
-	errorWrapperCheckErr(t, err, op)
-}