fix: restore debug logging when debug=1 is set via DSN

clickhouse_options.go

@@ -9,6 +9,7 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"os"
 	"strconv"
 	"strings"
 	"time"
@@ -438,14 +439,22 @@ func (o Options) setDefaults() *Options {
 // logger returns the appropriate logger based on the Options configuration.
 // Priority order:
 // 1. If Debug=true and Debugf is set, use legacy Debugf (backward compatibility)
-// 2. If Logger is set, use the provided logger
-// 3. Otherwise, use a noop logger (no logging)
+// 2. If Debug=true but no Debugf provided, use default stdout logger
+// 3. If Logger is set, use the provided logger
+// 4. Otherwise, use a noop logger (no logging)
 func (o *Options) logger() *slog.Logger {
 	// Backward compatibility: if legacy Debug/Debugf is set, use it
 	if o.Debug && o.Debugf != nil {
 		return newDebugfLogger(o.Debugf)
 	}
 
+	// If Debug=true but no Debugf provided, use default stdout logger
+	if o.Debug {
+		return slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{
+			Level: slog.LevelDebug,
+		}))
+	}
+
 	// If user provided a custom logger, use it
 	if o.Logger != nil {
 		return o.Logger

clickhouse_options_test.go

@@ -2,7 +2,9 @@ package clickhouse
 
 import (
 	"crypto/tls"
+	"log/slog"
 	"net/url"
+	"os"
 	"testing"
 	"time"
 
@@ -584,3 +586,47 @@ func parseURL(t *testing.T, v string) *url.URL {
 	require.NoError(t, err)
 	return u
 }
+
+func TestLogger(t *testing.T) {
+	t.Run("debug=1 via DSN produces non-noop logger", func(t *testing.T) {
+		opts, err := ParseDSN("clickhouse://127.0.0.1/test?debug=1")
+		require.NoError(t, err)
+		require.True(t, opts.Debug)
+
+		logger := opts.logger()
+		require.NotNil(t, logger)
+		// Verify it's not a noop logger by checking it has a handler
+		// The handler should not be *noopHandler
+		_, isNoop := logger.Handler().(*noopHandler)
+		assert.False(t, isNoop, "expected non-noop logger when debug=1")
+	})
+
+	t.Run("debug=false produces noop logger", func(t *testing.T) {
+		opts, err := ParseDSN("clickhouse://127.0.0.1/test")
+		require.NoError(t, err)
+		require.False(t, opts.Debug)
+
+		logger := opts.logger()
+		require.NotNil(t, logger)
+		_, isNoop := logger.Handler().(*noopHandler)
+		assert.True(t, isNoop, "expected noop logger when debug is not set")
+	})
+
+	t.Run("debug=true with Debugf uses legacy handler", func(t *testing.T) {
+		var logged string
+		opts := &Options{Debug: true, Debugf: func(format string, v ...any) {
+			logged = format
+		}}
+		logger := opts.logger()
+		require.NotNil(t, logger)
+		logger.Debug("test message")
+		assert.Equal(t, "%s", logged, "legacy handler uses %s format")
+	})
+
+	t.Run("custom Logger is used when provided", func(t *testing.T) {
+		customLogger := slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{Level: slog.LevelWarn}))
+		opts := &Options{Logger: customLogger}
+		logger := opts.logger()
+		assert.Equal(t, customLogger, logger)
+	})
+}