all: fix warning flagging the use of DeepEqual on error (ethereum#23624)

* core: fix warning flagging the use of DeepEqual on error

* apply the same change everywhere possible

* revert change that was committed by mistake

* fix build error

* Update config.go

* revert changes to ConfigCompatError

* review feedback

Co-authored-by: Felix Lange <[email protected]>

Author: gballet

Diff for: p2p/discover/v5wire/encoding_test.go

@@ -20,13 +20,13 @@ import (
 	"bytes"
 	"crypto/ecdsa"
 	"encoding/hex"
+	"errors"
 	"flag"
 	"fmt"
 	"io/ioutil"
 	"net"
 	"os"
 	"path/filepath"
-	"reflect"
 	"strings"
 	"testing"
 
@@ -555,7 +555,7 @@ func (n *handshakeTestNode) expectDecode(t *testing.T, ptype byte, p []byte) Pac
 
 func (n *handshakeTestNode) expectDecodeErr(t *testing.T, wantErr error, p []byte) {
 	t.Helper()
-	if _, err := n.decode(p); !reflect.DeepEqual(err, wantErr) {
+	if _, err := n.decode(p); !errors.Is(err, wantErr) {
 		t.Fatal(fmt.Errorf("(%s) got err %q, want %q", n.ln.ID().TerminalString(), err, wantErr))
 	}
 }

Diff for: p2p/server_test.go

@@ -370,6 +370,8 @@ func TestServerSetupConn(t *testing.T) {
 		clientkey, srvkey = newkey(), newkey()
 		clientpub         = &clientkey.PublicKey
 		srvpub            = &srvkey.PublicKey
+		fooErr            = errors.New("foo")
+		readErr           = errors.New("read error")
 	)
 	tests := []struct {
 		dontstart bool
@@ -387,10 +389,10 @@ func TestServerSetupConn(t *testing.T) {
 			wantCloseErr: errServerStopped,
 		},
 		{
-			tt:           &setupTransport{pubkey: clientpub, encHandshakeErr: errors.New("read error")},
+			tt:           &setupTransport{pubkey: clientpub, encHandshakeErr: readErr},
 			flags:        inboundConn,
 			wantCalls:    "doEncHandshake,close,",
-			wantCloseErr: errors.New("read error"),
+			wantCloseErr: readErr,
 		},
 		{
 			tt:           &setupTransport{pubkey: clientpub, phs: protoHandshake{ID: randomID().Bytes()}},
@@ -400,11 +402,11 @@ func TestServerSetupConn(t *testing.T) {
 			wantCloseErr: DiscUnexpectedIdentity,
 		},
 		{
-			tt:           &setupTransport{pubkey: clientpub, protoHandshakeErr: errors.New("foo")},
+			tt:           &setupTransport{pubkey: clientpub, protoHandshakeErr: fooErr},
 			dialDest:     enode.NewV4(clientpub, nil, 0, 0),
 			flags:        dynDialedConn,
 			wantCalls:    "doEncHandshake,doProtoHandshake,close,",
-			wantCloseErr: errors.New("foo"),
+			wantCloseErr: fooErr,
 		},
 		{
 			tt:           &setupTransport{pubkey: srvpub, phs: protoHandshake{ID: crypto.FromECDSAPub(srvpub)[1:]}},
@@ -443,7 +445,7 @@ func TestServerSetupConn(t *testing.T) {
 			}
 			p1, _ := net.Pipe()
 			srv.SetupConn(p1, test.flags, test.dialDest)
-			if !reflect.DeepEqual(test.tt.closeErr, test.wantCloseErr) {
+			if !errors.Is(test.tt.closeErr, test.wantCloseErr) {
 				t.Errorf("test %d: close error mismatch: got %q, want %q", i, test.tt.closeErr, test.wantCloseErr)
 			}
 			if test.tt.calls != test.wantCalls {

Diff for: rlp/raw_test.go

@@ -18,8 +18,8 @@ package rlp
 
 import (
 	"bytes"
+	"errors"
 	"io"
-	"reflect"
 	"testing"
 	"testing/quick"
 )
@@ -54,7 +54,7 @@ func TestCountValues(t *testing.T) {
 		if count != test.count {
 			t.Errorf("test %d: count mismatch, got %d want %d\ninput: %s", i, count, test.count, test.input)
 		}
-		if !reflect.DeepEqual(err, test.err) {
+		if !errors.Is(err, test.err) {
 			t.Errorf("test %d: err mismatch, got %q want %q\ninput: %s", i, err, test.err, test.input)
 		}
 	}

Diff for: rpc/websocket_test.go

@@ -18,13 +18,13 @@ package rpc
 
 import (
 	"context"
+	"errors"
 	"io"
 	"net"
 	"net/http"
 	"net/http/httptest"
 	"net/http/httputil"
 	"net/url"
-	"reflect"
 	"strings"
 	"sync/atomic"
 	"testing"
@@ -69,7 +69,7 @@ func TestWebsocketOriginCheck(t *testing.T) {
 		t.Fatal("no error for wrong origin")
 	}
 	wantErr := wsHandshakeError{websocket.ErrBadHandshake, "403 Forbidden"}
-	if !reflect.DeepEqual(err, wantErr) {
+	if !errors.Is(err, wantErr) {
 		t.Fatalf("wrong error for wrong origin: %q", err)
 	}