tests: add test to compare ctx canceled errors

Add test TestComparableCanceledContextErrors checking comparabily.
Refactored and satisfied review.

Fixes (#457)

Author: ermyar

CHANGELOG.md

@@ -15,8 +15,8 @@ Versioning](http://semver.org/spec/v2.0.0.html) except to the first release.
 ### Changed
 
 - Required Go version is `1.24` now (#456).
-- Now `connection.newFuture()` in case `<-ctx.Done()` returns wrapped error
-  provided by `ctx.Cause()`. Allows you compare it using `errors.Is/As` (#457).
+- Now cases of `<-ctx.Done()` returns wrapped error provided by `ctx.Cause()`.
+  Allows you compare it using `errors.Is/As` (#457).
 
 ### Fixed
 

connection.go

@@ -984,7 +984,7 @@ func (conn *Connection) newFuture(req Request) (fut *Future) {
 	if ctx != nil {
 		select {
 		case <-ctx.Done():
-			fut.SetError(fmt.Errorf("context is done (request ID %d) (%w)",
+			fut.SetError(fmt.Errorf("context is done (request ID %d): %w",
 				fut.requestId, context.Cause(ctx)))
 			shard.rmut.Unlock()
 			return
@@ -1027,7 +1027,8 @@ func (conn *Connection) contextWatchdog(fut *Future, ctx context.Context) {
 	case <-fut.done:
 		return
 	default:
-		conn.cancelFuture(fut, fmt.Errorf("context is done (request ID %d)", fut.requestId))
+		conn.cancelFuture(fut, fmt.Errorf("context is done (request ID %d): %w",
+			fut.requestId, context.Cause(ctx)))
 	}
 }
 

errors.go

@@ -31,7 +31,7 @@ type ClientError struct {
 
 // Error converts a ClientError to a string.
 func (clierr ClientError) Error() string {
-	return fmt.Sprintf("%s (%#x)", clierr.Msg, clierr.Code)
+	return fmt.Sprintf("%s (0x%x)", clierr.Msg, clierr.Code)
 }
 
 // Temporary returns true if next attempt to perform request may succeeded.
@@ -54,12 +54,11 @@ func (clierr ClientError) Temporary() bool {
 
 // Tarantool client error codes.
 const (
-	ErrConnectionNotReady uint32 = 0x4000 + iota
-	ErrConnectionClosed
-	ErrProtocolError
-	ErrTimeouted
-	ErrRateLimited
-	ErrConnectionShutdown
-	ErrIoError
-	ErrCancelledCtx
+	ErrConnectionNotReady = 0x4000 + iota
+	ErrConnectionClosed   = 0x4000 + iota
+	ErrProtocolError      = 0x4000 + iota
+	ErrTimeouted          = 0x4000 + iota
+	ErrRateLimited        = 0x4000 + iota
+	ErrConnectionShutdown = 0x4000 + iota
+	ErrIoError            = 0x4000 + iota
 )

example_test.go

@@ -2,7 +2,6 @@ package tarantool_test
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"net"
 	"regexp"
@@ -166,11 +165,9 @@ func ExamplePingRequest_Context() {
 	data, err := conn.Do(req).Get()
 	fmt.Println("Ping Resp data", data)
 	fmt.Println("Ping Error", regexp.MustCompile("[0-9]+").ReplaceAllString(err.Error(), "N"))
-	fmt.Println(errors.Is(err, context.DeadlineExceeded))
 	// Output:
 	// Ping Resp data []
-	// Ping Error context is done (request ID N) (context deadline exceeded)
-	// true
+	// Ping Error context is done (request ID N): context deadline exceeded
 }
 
 func ExampleSelectRequest() {

tarantool_test.go

@@ -50,7 +50,7 @@ type Member struct {
 }
 
 var contextDoneErrRegexp = regexp.MustCompile(
-	fmt.Sprintf(`^context is done \(request ID [0-9]+\) \(%s\)$`, "context canceled"))
+	`^context is done \(request ID [0-9]+\): context canceled$`)
 
 func (m *Member) EncodeMsgpack(e *msgpack.Encoder) error {
 	if err := e.EncodeArrayLen(2); err != nil {
@@ -2739,13 +2739,40 @@ func TestClientRequestObjectsWithPassedCanceledContext(t *testing.T) {
 	if !contextDoneErrRegexp.Match([]byte(err.Error())) {
 		t.Fatalf("Failed to catch an error from done context")
 	}
-	// Checking that we could use errors.Is to get known about error.
-	require.True(t, errors.Is(err, context.Canceled))
 	if resp != nil {
 		t.Fatalf("Response is not nil after the occurred error")
 	}
 }
 
+func TestComparableCanceledContextErrors(t *testing.T) {
+	conn := test_helpers.ConnectWithValidation(t, dialer, opts)
+	defer conn.Close()
+
+	// Checking comparable with simple context.WithCancel.
+	ctx, cancel := context.WithCancel(context.Background())
+	req := NewPingRequest().Context(ctx)
+	cancel()
+	_, err := conn.Do(req).Get()
+	require.True(t, errors.Is(err, context.Canceled), err.Error())
+
+	// Checking comparable with simple context.WithTimeout.
+	timeout := time.Nanosecond
+	ctx, cancel = context.WithTimeout(context.Background(), timeout)
+	req = NewPingRequest().Context(ctx)
+	defer cancel()
+	_, err = conn.Do(req).Get()
+	require.True(t, errors.Is(err, context.DeadlineExceeded), err.Error())
+
+	// Checking comparable with context.WithCancelCause.
+	// Shows ability to compare with custom errors (also with ClientError).
+	ctxCause, cancelCause := context.WithCancelCause(context.Background())
+	req = NewPingRequest().Context(ctxCause)
+	cancelCause(ClientError{ErrConnectionClosed, "something went wrong"})
+	_, err = conn.Do(req).Get()
+	var tmpErr ClientError
+	require.True(t, errors.As(err, &tmpErr), tmpErr.Error())
+}
+
 // waitCtxRequest waits for the WaitGroup in Body() call and returns
 // the context from Ctx() call. The request helps us to make sure that
 // the context's cancel() call is called before a response received.
@@ -3302,7 +3329,6 @@ func TestClientIdRequestObjectWithPassedCanceledContext(t *testing.T) {
 	resp, err := conn.Do(req).Get()
 	require.Nilf(t, resp, "Response is empty")
 	require.NotNilf(t, err, "Error is not empty")
-	require.True(t, errors.Is(err, context.Canceled))
 	require.Regexp(t, contextDoneErrRegexp, err.Error())
 }