diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..85e7c1d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/.idea/
diff --git a/buffer.go b/buffer.go
new file mode 100644
index 0000000..4d7321a
--- /dev/null
+++ b/buffer.go
@@ -0,0 +1,46 @@
+package tint
+
+import "sync"
+
+type buffer []byte
+
+var bufPool = sync.Pool{
+ New: func() any {
+ b := make(buffer, 0, 1024)
+ return (*buffer)(&b)
+ },
+}
+
+func newBuffer() *buffer {
+ return bufPool.Get().(*buffer)
+}
+
+func (b *buffer) Free() {
+ // To reduce peak allocation, return only smaller buffers to the pool.
+ const maxBufferSize = 16 << 10
+ if cap(*b) <= maxBufferSize {
+ *b = (*b)[:0]
+ bufPool.Put(b)
+ }
+}
+func (b *buffer) Write(bytes []byte) (int, error) {
+ *b = append(*b, bytes...)
+ return len(bytes), nil
+}
+
+func (b *buffer) WriteByte(char byte) error {
+ *b = append(*b, char)
+ return nil
+}
+
+func (b *buffer) WriteString(str string) (int, error) {
+ *b = append(*b, str...)
+ return len(str), nil
+}
+
+func (b *buffer) WriteStringIf(ok bool, str string) (int, error) {
+ if !ok {
+ return 0, nil
+ }
+ return b.WriteString(str)
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..6b08636
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module toastielab.dev/toastie-stuff/tint
+
+go 1.22
diff --git a/handler.go b/handler.go
new file mode 100644
index 0000000..6bb8536
--- /dev/null
+++ b/handler.go
@@ -0,0 +1,534 @@
+/*
+Package tint implements a zero-dependency [slog.Handler] that writes tinted
+(colorized) logs. The output format is inspired by the [zerolog.ConsoleWriter]
+and [slog.TextHandler].
+
+The output format can be customized using [Options], which is a drop-in
+replacement for [slog.HandlerOptions].
+
+# Customizing Colors
+
+Colors can be customized using the `Options.LevelColors` and `Options.Colors` attributes.
+See [tint.Options] for details.
+
+ // ANSI escape codes: https://en.wikipedia.org/wiki/ANSI_escape_code
+ const (
+ ansiFaint = "\033[2m"
+ ansiBrightRed = "\033[91m"
+ ansiBrightRedFaint = "\033[91;2m"
+ ansiBrightGreen = "\033[92m"
+ ansiBrightYellow = "\033[93m"
+ ansiBrightYellowBold = "\033[93;1m"
+ ansiBrightBlueBold = "\033[94;1m"
+ ansiBrightMagenta = "\033[95m"
+ )
+
+ // create a new logger with custom colors
+ w := os.Stderr
+ logger := slog.New(
+ tint.NewHandler(w, &tint.Options{
+ LevelColors: map[slog.Level]string{
+ slog.LevelDebug: ansiBrightMagenta,
+ slog.LevelInfo: ansiBrightGreen,
+ slog.LevelWarn: ansiBrightYellow,
+ slog.LevelError: ansiBrightRed,
+ },
+ Colors: map[tint.Kind]string{
+ tint.KindTime: ansiBrightYellowBold,
+ tint.KindSourceFile: ansiFaint,
+ tint.KindSourceSeparator: ansiFaint,
+ tint.KindSourceLine: ansiFaint,
+ tint.KindMessage: ansiBrightBlueBold,
+ tint.KindKey: ansiFaint,
+ tint.KindSeparator: ansiFaint,
+ tint.KindValue: ansiBrightBlueBold,
+ tint.KindErrorKey: ansiBrightRedFaint,
+ tint.KindErrorSeparator: ansiBrightRedFaint,
+ tint.KindErrorValue: ansiBrightRed,
+ },
+ }),
+ )
+
+# Customize Attributes
+
+Options.ReplaceAttr can be used to alter or drop attributes. If set, it is
+called on each non-group attribute before it is logged.
+See [slog.HandlerOptions] for details.
+
+ w := os.Stderr
+ logger := slog.New(
+ tint.NewHandler(w, &tint.Options{
+ ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
+ if a.Key == slog.TimeKey && len(groups) == 0 {
+ return slog.Attr{}
+ }
+ return a
+ },
+ }),
+ )
+
+# Automatically Enable Colors
+
+Colors are enabled by default and can be disabled using the Options.NoColor
+attribute. To automatically enable colors based on the terminal capabilities,
+use e.g. the [go-isatty] package.
+
+ w := os.Stderr
+ logger := slog.New(
+ tint.NewHandler(w, &tint.Options{
+ NoColor: !isatty.IsTerminal(w.Fd()),
+ }),
+ )
+
+# Windows Support
+
+Color support on Windows can be added by using e.g. the [go-colorable] package.
+
+ w := os.Stderr
+ logger := slog.New(
+ tint.NewHandler(colorable.NewColorable(w), nil),
+ )
+
+[zerolog.ConsoleWriter]: https://pkg.go.dev/github.com/rs/zerolog#ConsoleWriter
+[go-isatty]: https://pkg.go.dev/github.com/mattn/go-isatty
+[go-colorable]: https://pkg.go.dev/github.com/mattn/go-colorable
+*/
+package tint
+
+import (
+ "context"
+ "encoding"
+ "fmt"
+ "io"
+ "log/slog"
+ "path/filepath"
+ "runtime"
+ "strconv"
+ "sync"
+ "time"
+ "unicode"
+)
+
+// ANSI modes
+const (
+ ansiReset = "\033[0m"
+ ansiFaint = "\033[2m"
+ ansiBrightRed = "\033[91m"
+ ansiBrightGreen = "\033[92m"
+ ansiBrightYellow = "\033[93m"
+ ansiBrightRedFaint = "\033[91;2m"
+)
+
+const errKey = "err"
+
+var (
+ defaultLevel = slog.LevelInfo
+ defaultTimeFormat = time.StampMilli
+ defaultLevelColors = map[slog.Level]string{
+ slog.LevelDebug: ansiFaint,
+ slog.LevelInfo: ansiBrightGreen,
+ slog.LevelWarn: ansiBrightYellow,
+ slog.LevelError: ansiBrightRed,
+ }
+ defaultColors = map[Kind]string{
+ KindTime: ansiFaint,
+ KindSourceFile: ansiFaint,
+ KindSourceSeparator: ansiFaint,
+ KindSourceLine: ansiFaint,
+ KindMessage: "",
+ KindKey: ansiFaint,
+ KindSeparator: ansiFaint,
+ KindValue: "",
+ KindErrorKey: ansiBrightRedFaint,
+ KindErrorSeparator: ansiBrightRedFaint,
+ KindErrorValue: ansiBrightRed,
+ }
+)
+
+type Kind int
+
+const (
+ KindTime Kind = iota
+ KindSourceFile
+ KindSourceSeparator
+ KindSourceLine
+ KindMessage
+ KindKey
+ KindSeparator
+ KindValue
+ KindErrorKey
+ KindErrorSeparator
+ KindErrorValue
+)
+
+// Options for a slog.Handler that writes tinted logs. A zero Options consists
+// entirely of default values.
+//
+// Options can be used as a drop-in replacement for [slog.HandlerOptions].
+type Options struct {
+ // Enable source code location (Default: false)
+ AddSource bool
+
+ // Minimum level to log (Default: slog.LevelInfo)
+ Level slog.Leveler
+
+ // ReplaceAttr is called to rewrite each non-group attribute before it is logged.
+ // See https://pkg.go.dev/log/slog#HandlerOptions for details.
+ ReplaceAttr func(groups []string, attr slog.Attr) slog.Attr
+
+ // Time format (Default: time.StampMilli)
+ TimeFormat string
+
+ // Disable color (Default: false)
+ NoColor bool
+
+ // Level colors (Default: debug: faint, info: green, warn: yellow, error: red)
+ LevelColors map[slog.Level]string
+
+ // Colors of certain parts of the log message
+ Colors map[Kind]string
+}
+
+// NewHandler creates a [slog.Handler] that writes tinted logs to Writer w,
+// using the default options. If opts is nil, the default options are used.
+func NewHandler(w io.Writer, opts *Options) slog.Handler {
+ h := &handler{
+ w: w,
+ level: defaultLevel,
+ timeFormat: defaultTimeFormat,
+ levelColors: defaultLevelColors,
+ colors: defaultColors,
+ }
+ if opts == nil {
+ return h
+ }
+
+ h.addSource = opts.AddSource
+ if opts.Level != nil {
+ h.level = opts.Level
+ }
+ h.replaceAttr = opts.ReplaceAttr
+ if opts.TimeFormat != "" {
+ h.timeFormat = opts.TimeFormat
+ }
+ h.noColor = opts.NoColor
+ if opts.LevelColors != nil {
+ h.levelColors = opts.LevelColors
+ }
+ if opts.Colors != nil {
+ h.colors = opts.Colors
+ }
+ return h
+}
+
+// handler implements a [slog.Handler].
+type handler struct {
+ attrsPrefix string
+ groupPrefix string
+ groups []string
+
+ mu sync.Mutex
+ w io.Writer
+
+ addSource bool
+ level slog.Leveler
+ replaceAttr func([]string, slog.Attr) slog.Attr
+ timeFormat string
+ noColor bool
+ levelColors map[slog.Level]string
+ colors map[Kind]string
+}
+
+func (h *handler) clone() *handler {
+ return &handler{
+ attrsPrefix: h.attrsPrefix,
+ groupPrefix: h.groupPrefix,
+ groups: h.groups,
+ w: h.w,
+ addSource: h.addSource,
+ level: h.level,
+ replaceAttr: h.replaceAttr,
+ timeFormat: h.timeFormat,
+ noColor: h.noColor,
+ levelColors: h.levelColors,
+ colors: h.colors,
+ }
+}
+
+func (h *handler) Enabled(_ context.Context, level slog.Level) bool {
+ return level >= h.level.Level()
+}
+
+func (h *handler) Handle(_ context.Context, r slog.Record) error {
+ // get a buffer from the sync pool
+ buf := newBuffer()
+ defer buf.Free()
+
+ rep := h.replaceAttr
+
+ // write time
+ if !r.Time.IsZero() {
+ val := r.Time.Round(0) // strip monotonic to match Attr behavior
+ if rep == nil {
+ h.appendTime(buf, r.Time)
+ buf.WriteByte(' ')
+ } else if a := rep(nil /* groups */, slog.Time(slog.TimeKey, val)); a.Key != "" {
+ if a.Value.Kind() == slog.KindTime {
+ h.appendTime(buf, a.Value.Time())
+ } else {
+ h.appendValue(buf, a.Value, false)
+ }
+ buf.WriteByte(' ')
+ }
+ }
+
+ // write level
+ if rep == nil {
+ h.appendLevel(buf, r.Level)
+ buf.WriteByte(' ')
+ } else if a := rep(nil /* groups */, slog.Any(slog.LevelKey, r.Level)); a.Key != "" {
+ h.appendValue(buf, a.Value, false)
+ buf.WriteByte(' ')
+ }
+
+ // write source
+ if h.addSource {
+ fs := runtime.CallersFrames([]uintptr{r.PC})
+ f, _ := fs.Next()
+ if f.File != "" {
+ src := &slog.Source{
+ Function: f.Function,
+ File: f.File,
+ Line: f.Line,
+ }
+
+ if rep == nil {
+ h.appendSource(buf, src)
+ buf.WriteByte(' ')
+ } else if a := rep(nil /* groups */, slog.Any(slog.SourceKey, src)); a.Key != "" {
+ h.appendValue(buf, a.Value, false)
+ buf.WriteByte(' ')
+ }
+ }
+ }
+
+ // write message
+ if rep == nil {
+ buf.WriteStringIf(!h.noColor, h.colors[KindMessage])
+ buf.WriteString(r.Message)
+ buf.WriteStringIf(!h.noColor, ansiReset)
+ buf.WriteByte(' ')
+ } else if a := rep(nil /* groups */, slog.String(slog.MessageKey, r.Message)); a.Key != "" {
+ h.appendValue(buf, a.Value, false)
+ buf.WriteByte(' ')
+ }
+
+ // write handler attributes
+ if len(h.attrsPrefix) > 0 {
+ buf.WriteString(h.attrsPrefix)
+ }
+
+ // write attributes
+ r.Attrs(func(attr slog.Attr) bool {
+ h.appendAttr(buf, attr, h.groupPrefix, h.groups)
+ return true
+ })
+
+ if len(*buf) == 0 {
+ return nil
+ }
+ (*buf)[len(*buf)-1] = '\n' // replace last space with newline
+
+ h.mu.Lock()
+ defer h.mu.Unlock()
+
+ _, err := h.w.Write(*buf)
+ return err
+}
+
+func (h *handler) WithAttrs(attrs []slog.Attr) slog.Handler {
+ if len(attrs) == 0 {
+ return h
+ }
+ h2 := h.clone()
+
+ buf := newBuffer()
+ defer buf.Free()
+
+ // write attributes to buffer
+ for _, attr := range attrs {
+ h.appendAttr(buf, attr, h.groupPrefix, h.groups)
+ }
+ h2.attrsPrefix = h.attrsPrefix + string(*buf)
+ return h2
+}
+
+func (h *handler) WithGroup(name string) slog.Handler {
+ if name == "" {
+ return h
+ }
+ h2 := h.clone()
+ h2.groupPrefix += name + "."
+ h2.groups = append(h2.groups, name)
+ return h2
+}
+
+func (h *handler) appendTime(buf *buffer, t time.Time) {
+ buf.WriteStringIf(!h.noColor, h.colors[KindTime])
+ *buf = t.AppendFormat(*buf, h.timeFormat)
+ buf.WriteStringIf(!h.noColor, ansiReset)
+}
+
+func (h *handler) appendLevel(buf *buffer, level slog.Level) {
+ switch {
+ case level < slog.LevelInfo:
+ buf.WriteStringIf(!h.noColor, h.levelColors[level])
+ buf.WriteString("DBG")
+ appendLevelDelta(buf, level-slog.LevelDebug)
+ buf.WriteStringIf(!h.noColor, ansiReset)
+ case level < slog.LevelWarn:
+ buf.WriteStringIf(!h.noColor, h.levelColors[level])
+ buf.WriteString("INF")
+ appendLevelDelta(buf, level-slog.LevelInfo)
+ buf.WriteStringIf(!h.noColor, ansiReset)
+ case level < slog.LevelError:
+ buf.WriteStringIf(!h.noColor, h.levelColors[level])
+ buf.WriteString("WRN")
+ appendLevelDelta(buf, level-slog.LevelWarn)
+ buf.WriteStringIf(!h.noColor, ansiReset)
+ default:
+ buf.WriteStringIf(!h.noColor, h.levelColors[level])
+ buf.WriteString("ERR")
+ appendLevelDelta(buf, level-slog.LevelError)
+ buf.WriteStringIf(!h.noColor, ansiReset)
+ }
+}
+
+func appendLevelDelta(buf *buffer, delta slog.Level) {
+ if delta == 0 {
+ return
+ } else if delta > 0 {
+ buf.WriteByte('+')
+ }
+ *buf = strconv.AppendInt(*buf, int64(delta), 10)
+}
+
+func (h *handler) appendSource(buf *buffer, src *slog.Source) {
+ dir, file := filepath.Split(src.File)
+
+ buf.WriteStringIf(!h.noColor, h.colors[KindSourceFile])
+ buf.WriteString(filepath.Join(filepath.Base(dir), file))
+ buf.WriteStringIf(!h.noColor, ansiReset+h.colors[KindSourceSeparator])
+ buf.WriteByte(':')
+ buf.WriteStringIf(!h.noColor, ansiReset+h.colors[KindSourceLine])
+ buf.WriteString(strconv.Itoa(src.Line))
+ buf.WriteStringIf(!h.noColor, ansiReset)
+}
+
+func (h *handler) appendAttr(buf *buffer, attr slog.Attr, groupsPrefix string, groups []string) {
+ attr.Value = attr.Value.Resolve()
+ if rep := h.replaceAttr; rep != nil && attr.Value.Kind() != slog.KindGroup {
+ attr = rep(groups, attr)
+ attr.Value = attr.Value.Resolve()
+ }
+
+ if attr.Equal(slog.Attr{}) {
+ return
+ }
+
+ if attr.Value.Kind() == slog.KindGroup {
+ if attr.Key != "" {
+ groupsPrefix += attr.Key + "."
+ groups = append(groups, attr.Key)
+ }
+ for _, groupAttr := range attr.Value.Group() {
+ h.appendAttr(buf, groupAttr, groupsPrefix, groups)
+ }
+ } else if err, ok := attr.Value.Any().(error); ok && attr.Key == errKey {
+ h.appendError(buf, err, groupsPrefix)
+ buf.WriteByte(' ')
+ } else {
+ h.appendKey(buf, attr.Key, groupsPrefix)
+ h.appendValue(buf, attr.Value, true)
+ buf.WriteByte(' ')
+ }
+}
+
+func (h *handler) appendKey(buf *buffer, key, groups string) {
+ buf.WriteStringIf(!h.noColor, h.colors[KindKey])
+ appendString(buf, groups+key, true)
+ buf.WriteStringIf(!h.noColor, ansiReset+h.colors[KindSeparator])
+ buf.WriteByte('=')
+ buf.WriteStringIf(!h.noColor, ansiReset)
+}
+
+func (h *handler) appendValue(buf *buffer, v slog.Value, quote bool) {
+ buf.WriteStringIf(!h.noColor, h.colors[KindValue])
+ switch v.Kind() {
+ case slog.KindString:
+ appendString(buf, v.String(), quote)
+ case slog.KindInt64:
+ *buf = strconv.AppendInt(*buf, v.Int64(), 10)
+ case slog.KindUint64:
+ *buf = strconv.AppendUint(*buf, v.Uint64(), 10)
+ case slog.KindFloat64:
+ *buf = strconv.AppendFloat(*buf, v.Float64(), 'g', -1, 64)
+ case slog.KindBool:
+ *buf = strconv.AppendBool(*buf, v.Bool())
+ case slog.KindDuration:
+ appendString(buf, v.Duration().String(), quote)
+ case slog.KindTime:
+ appendString(buf, v.Time().String(), quote)
+ case slog.KindAny:
+ switch cv := v.Any().(type) {
+ case slog.Level:
+ h.appendLevel(buf, cv)
+ case encoding.TextMarshaler:
+ data, err := cv.MarshalText()
+ if err != nil {
+ break
+ }
+ appendString(buf, string(data), quote)
+ case *slog.Source:
+ h.appendSource(buf, cv)
+ default:
+ appendString(buf, fmt.Sprintf("%+v", v.Any()), quote)
+ }
+ }
+ buf.WriteStringIf(!h.noColor, ansiReset)
+}
+
+func (h *handler) appendError(buf *buffer, err error, groupsPrefix string) {
+ buf.WriteStringIf(!h.noColor, h.colors[KindErrorKey])
+ appendString(buf, groupsPrefix+errKey, true)
+ buf.WriteStringIf(!h.noColor, ansiReset+h.colors[KindErrorSeparator])
+ buf.WriteByte('=')
+ buf.WriteStringIf(!h.noColor, ansiReset+h.colors[KindErrorValue])
+ appendString(buf, err.Error(), true)
+ buf.WriteStringIf(!h.noColor, ansiReset)
+}
+
+func appendString(buf *buffer, s string, quote bool) {
+ if quote && needsQuoting(s) {
+ *buf = strconv.AppendQuote(*buf, s)
+ } else {
+ buf.WriteString(s)
+ }
+}
+
+func needsQuoting(s string) bool {
+ if len(s) == 0 {
+ return true
+ }
+ for _, r := range s {
+ if unicode.IsSpace(r) || r == '"' || r == '=' || !unicode.IsPrint(r) {
+ return true
+ }
+ }
+ return false
+}
+
+// Err returns slog.Any("err", err)
+func Err(err error) slog.Attr {
+ return slog.Any(errKey, err)
+}
diff --git a/handler_test.go b/handler_test.go
new file mode 100644
index 0000000..1a1b882
--- /dev/null
+++ b/handler_test.go
@@ -0,0 +1,581 @@
+package tint_test
+
+import (
+ "bytes"
+ "context"
+ "errors"
+ "io"
+ "log/slog"
+ "os"
+ "slices"
+ "strconv"
+ "strings"
+ "testing"
+ "time"
+
+ "toastielab.dev/toastie-stuff/tint"
+)
+
+var faketime = time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC)
+
+func Example() {
+ slog.SetDefault(slog.New(tint.NewHandler(os.Stderr, &tint.Options{
+ Level: slog.LevelDebug,
+ TimeFormat: time.Kitchen,
+ })))
+
+ slog.Info("Starting server", "addr", ":8080", "env", "production")
+ slog.Debug("Connected to DB", "db", "myapp", "host", "localhost:5432")
+ slog.Warn("Slow request", "method", "GET", "path", "/users", "duration", 497*time.Millisecond)
+ slog.Error("DB connection lost", tint.Err(errors.New("connection reset")), "db", "myapp")
+ // Output:
+}
+
+// Run test with "faketime" tag:
+//
+// TZ="" go test -tags=faketime
+func TestHandler(t *testing.T) {
+ if !faketime.Equal(time.Now()) {
+ t.Skip(`skipping test; run with "-tags=faketime"`)
+ }
+
+ tests := []struct {
+ Opts *tint.Options
+ F func(l *slog.Logger)
+ Want string
+ }{
+ {
+ F: func(l *slog.Logger) {
+ l.Info("test", "key", "val")
+ },
+ Want: `Nov 10 23:00:00.000 INF test key=val`,
+ },
+ {
+ F: func(l *slog.Logger) {
+ l.Error("test", tint.Err(errors.New("fail")))
+ },
+ Want: `Nov 10 23:00:00.000 ERR test err=fail`,
+ },
+ {
+ F: func(l *slog.Logger) {
+ l.Info("test", slog.Group("group", slog.String("key", "val"), tint.Err(errors.New("fail"))))
+ },
+ Want: `Nov 10 23:00:00.000 INF test group.key=val group.err=fail`,
+ },
+ {
+ F: func(l *slog.Logger) {
+ l.WithGroup("group").Info("test", "key", "val")
+ },
+ Want: `Nov 10 23:00:00.000 INF test group.key=val`,
+ },
+ {
+ F: func(l *slog.Logger) {
+ l.With("key", "val").Info("test", "key2", "val2")
+ },
+ Want: `Nov 10 23:00:00.000 INF test key=val key2=val2`,
+ },
+ {
+ F: func(l *slog.Logger) {
+ l.Info("test", "k e y", "v a l")
+ },
+ Want: `Nov 10 23:00:00.000 INF test "k e y"="v a l"`,
+ },
+ {
+ F: func(l *slog.Logger) {
+ l.WithGroup("g r o u p").Info("test", "key", "val")
+ },
+ Want: `Nov 10 23:00:00.000 INF test "g r o u p.key"=val`,
+ },
+ {
+ F: func(l *slog.Logger) {
+ l.Info("test", "slice", []string{"a", "b", "c"}, "map", map[string]int{"a": 1, "b": 2, "c": 3})
+ },
+ Want: `Nov 10 23:00:00.000 INF test slice="[a b c]" map="map[a:1 b:2 c:3]"`,
+ },
+ {
+ Opts: &tint.Options{
+ AddSource: true,
+ },
+ F: func(l *slog.Logger) {
+ l.Info("test", "key", "val")
+ },
+ Want: `Nov 10 23:00:00.000 INF tint/handler_test.go:100 test key=val`,
+ },
+ {
+ Opts: &tint.Options{
+ TimeFormat: time.Kitchen,
+ },
+ F: func(l *slog.Logger) {
+ l.Info("test", "key", "val")
+ },
+ Want: `11:00PM INF test key=val`,
+ },
+ {
+ Opts: &tint.Options{
+ ReplaceAttr: drop(slog.TimeKey),
+ },
+ F: func(l *slog.Logger) {
+ l.Info("test", "key", "val")
+ },
+ Want: `INF test key=val`,
+ },
+ {
+ Opts: &tint.Options{
+ ReplaceAttr: drop(slog.LevelKey),
+ },
+ F: func(l *slog.Logger) {
+ l.Info("test", "key", "val")
+ },
+ Want: `Nov 10 23:00:00.000 test key=val`,
+ },
+ {
+ Opts: &tint.Options{
+ ReplaceAttr: drop(slog.MessageKey),
+ },
+ F: func(l *slog.Logger) {
+ l.Info("test", "key", "val")
+ },
+ Want: `Nov 10 23:00:00.000 INF key=val`,
+ },
+ {
+ Opts: &tint.Options{
+ ReplaceAttr: drop(slog.TimeKey, slog.LevelKey, slog.MessageKey),
+ },
+ F: func(l *slog.Logger) {
+ l.Info("test", "key", "val")
+ },
+ Want: `key=val`,
+ },
+ {
+ Opts: &tint.Options{
+ ReplaceAttr: drop("key"),
+ },
+ F: func(l *slog.Logger) {
+ l.Info("test", "key", "val")
+ },
+ Want: `Nov 10 23:00:00.000 INF test`,
+ },
+ {
+ Opts: &tint.Options{
+ ReplaceAttr: drop("key"),
+ },
+ F: func(l *slog.Logger) {
+ l.WithGroup("group").Info("test", "key", "val", "key2", "val2")
+ },
+ Want: `Nov 10 23:00:00.000 INF test group.key=val group.key2=val2`,
+ },
+ {
+ Opts: &tint.Options{
+ ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
+ if a.Key == "key" && len(groups) == 1 && groups[0] == "group" {
+ return slog.Attr{}
+ }
+ return a
+ },
+ },
+ F: func(l *slog.Logger) {
+ l.WithGroup("group").Info("test", "key", "val", "key2", "val2")
+ },
+ Want: `Nov 10 23:00:00.000 INF test group.key2=val2`,
+ },
+ {
+ Opts: &tint.Options{
+ ReplaceAttr: replace(slog.IntValue(42), slog.TimeKey),
+ },
+ F: func(l *slog.Logger) {
+ l.Info("test", "key", "val")
+ },
+ Want: `42 INF test key=val`,
+ },
+ {
+ Opts: &tint.Options{
+ ReplaceAttr: replace(slog.StringValue("INFO"), slog.LevelKey),
+ },
+ F: func(l *slog.Logger) {
+ l.Info("test", "key", "val")
+ },
+ Want: `Nov 10 23:00:00.000 INFO test key=val`,
+ },
+ {
+ Opts: &tint.Options{
+ ReplaceAttr: replace(slog.IntValue(42), slog.MessageKey),
+ },
+ F: func(l *slog.Logger) {
+ l.Info("test", "key", "val")
+ },
+ Want: `Nov 10 23:00:00.000 INF 42 key=val`,
+ },
+ {
+ Opts: &tint.Options{
+ ReplaceAttr: replace(slog.IntValue(42), "key"),
+ },
+ F: func(l *slog.Logger) {
+ l.With("key", "val").Info("test", "key2", "val2")
+ },
+ Want: `Nov 10 23:00:00.000 INF test key=42 key2=val2`,
+ },
+ {
+ Opts: &tint.Options{
+ ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
+ return slog.Attr{}
+ },
+ },
+ F: func(l *slog.Logger) {
+ l.Info("test", "key", "val")
+ },
+ Want: ``,
+ },
+ {
+ F: func(l *slog.Logger) {
+ l.Info("test", "key", "")
+ },
+ Want: `Nov 10 23:00:00.000 INF test key=""`,
+ },
+ {
+ F: func(l *slog.Logger) {
+ l.Info("test", "", "val")
+ },
+ Want: `Nov 10 23:00:00.000 INF test ""=val`,
+ },
+ {
+ F: func(l *slog.Logger) {
+ l.Info("test", "", "")
+ },
+ Want: `Nov 10 23:00:00.000 INF test ""=""`,
+ },
+
+ { // https://toastielab.dev/toastie-stuff/tint/issues/8
+ F: func(l *slog.Logger) {
+ l.Log(context.TODO(), slog.LevelInfo+1, "test")
+ },
+ Want: `Nov 10 23:00:00.000 INF+1 test`,
+ },
+ {
+ Opts: &tint.Options{
+ Level: slog.LevelDebug - 1,
+ },
+ F: func(l *slog.Logger) {
+ l.Log(context.TODO(), slog.LevelDebug-1, "test")
+ },
+ Want: `Nov 10 23:00:00.000 DBG-1 test`,
+ },
+ { // https://toastielab.dev/toastie-stuff/tint/issues/12
+ F: func(l *slog.Logger) {
+ l.Error("test", slog.Any("error", errors.New("fail")))
+ },
+ Want: `Nov 10 23:00:00.000 ERR test error=fail`,
+ },
+ { // https://toastielab.dev/toastie-stuff/tint/issues/15
+ F: func(l *slog.Logger) {
+ l.Error("test", tint.Err(nil))
+ },
+ Want: `Nov 10 23:00:00.000 ERR test err=<nil>`,
+ },
+ { // https://toastielab.dev/toastie-stuff/tint/pull/26
+ Opts: &tint.Options{
+ ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
+ if a.Key == slog.TimeKey && len(groups) == 0 {
+ return slog.Time(slog.TimeKey, a.Value.Time().Add(24*time.Hour))
+ }
+ return a
+ },
+ },
+ F: func(l *slog.Logger) {
+ l.Error("test")
+ },
+ Want: `Nov 11 23:00:00.000 ERR test`,
+ },
+ { // https://toastielab.dev/toastie-stuff/tint/pull/27
+ F: func(l *slog.Logger) {
+ l.Info("test", "a", "b", slog.Group("", slog.String("c", "d")), "e", "f")
+ },
+ Want: `Nov 10 23:00:00.000 INF test a=b c=d e=f`,
+ },
+ { // https://toastielab.dev/toastie-stuff/tint/pull/30
+ // drop built-in attributes in a grouped log
+ Opts: &tint.Options{
+ ReplaceAttr: drop(slog.TimeKey, slog.LevelKey, slog.MessageKey, slog.SourceKey),
+ AddSource: true,
+ },
+ F: func(l *slog.Logger) {
+ l.WithGroup("group").Info("test", "key", "val")
+ },
+ Want: `group.key=val`,
+ },
+ { // https://toastielab.dev/toastie-stuff/tint/issues/36
+ Opts: &tint.Options{
+ ReplaceAttr: func(g []string, a slog.Attr) slog.Attr {
+ if len(g) == 0 && a.Key == slog.LevelKey {
+ _ = a.Value.Any().(slog.Level)
+ }
+ return a
+ },
+ },
+ F: func(l *slog.Logger) {
+ l.Info("test")
+ },
+ Want: `Nov 10 23:00:00.000 INF test`,
+ },
+ { // https://toastielab.dev/toastie-stuff/tint/issues/37
+ Opts: &tint.Options{
+ AddSource: true,
+ ReplaceAttr: func(g []string, a slog.Attr) slog.Attr {
+ return a
+ },
+ },
+ F: func(l *slog.Logger) {
+ l.Info("test")
+ },
+ Want: `Nov 10 23:00:00.000 INF tint/handler_test.go:327 test`,
+ },
+ { // https://toastielab.dev/toastie-stuff/tint/issues/44
+ F: func(l *slog.Logger) {
+ l = l.WithGroup("group")
+ l.Error("test", tint.Err(errTest))
+ },
+ Want: `Nov 10 23:00:00.000 ERR test group.err=fail`,
+ },
+ { // https://github.com/lmittmann/tint/issues/55
+ F: func(l *slog.Logger) {
+ l.Info("test", "key", struct {
+ A int
+ B *string
+ }{A: 123})
+ },
+ Want: `Nov 10 23:00:00.000 INF test key="{A:123 B:<nil>}"`,
+ },
+ }
+
+ for i, test := range tests {
+ t.Run(strconv.Itoa(i), func(t *testing.T) {
+ var buf bytes.Buffer
+ if test.Opts == nil {
+ test.Opts = &tint.Options{}
+ }
+ test.Opts.NoColor = true
+ l := slog.New(tint.NewHandler(&buf, test.Opts))
+ test.F(l)
+
+ got := strings.TrimRight(buf.String(), "\n")
+ if test.Want != got {
+ t.Fatalf("(-want +got)\n- %s\n+ %s", test.Want, got)
+ }
+ })
+ }
+}
+
+// drop returns a ReplaceAttr that drops the given keys.
+func drop(keys ...string) func([]string, slog.Attr) slog.Attr {
+ return func(groups []string, a slog.Attr) slog.Attr {
+ if len(groups) > 0 {
+ return a
+ }
+
+ for _, key := range keys {
+ if a.Key == key {
+ a = slog.Attr{}
+ }
+ }
+ return a
+ }
+}
+
+func replace(new slog.Value, keys ...string) func([]string, slog.Attr) slog.Attr {
+ return func(groups []string, a slog.Attr) slog.Attr {
+ if len(groups) > 0 {
+ return a
+ }
+
+ for _, key := range keys {
+ if a.Key == key {
+ a.Value = new
+ }
+ }
+ return a
+ }
+}
+
+func TestReplaceAttr(t *testing.T) {
+ tests := [][]any{
+ {},
+ {"key", "val"},
+ {"key", "val", slog.Group("group", "key2", "val2")},
+ {"key", "val", slog.Group("group", "key2", "val2", slog.Group("group2", "key3", "val3"))},
+ }
+
+ type replaceAttrParams struct {
+ Groups []string
+ Attr slog.Attr
+ }
+
+ replaceAttrRecorder := func(record *[]replaceAttrParams) func([]string, slog.Attr) slog.Attr {
+ return func(groups []string, a slog.Attr) slog.Attr {
+ *record = append(*record, replaceAttrParams{groups, a})
+ return a
+ }
+ }
+
+ for i, test := range tests {
+ t.Run(strconv.Itoa(i), func(t *testing.T) {
+ slogRecord := make([]replaceAttrParams, 0)
+ slogLogger := slog.New(slog.NewTextHandler(io.Discard, &slog.HandlerOptions{
+ ReplaceAttr: replaceAttrRecorder(&slogRecord),
+ }))
+ slogLogger.Log(context.TODO(), slog.LevelInfo, "", test...)
+
+ tintRecord := make([]replaceAttrParams, 0)
+ tintLogger := slog.New(tint.NewHandler(io.Discard, &tint.Options{
+ ReplaceAttr: replaceAttrRecorder(&tintRecord),
+ }))
+ tintLogger.Log(context.TODO(), slog.LevelInfo, "", test...)
+
+ if !slices.EqualFunc(slogRecord, tintRecord, func(a, b replaceAttrParams) bool {
+ return slices.Equal(a.Groups, b.Groups) && a.Attr.Equal(b.Attr)
+ }) {
+ t.Fatalf("(-want +got)\n- %v\n+ %v", slogRecord, tintRecord)
+ }
+ })
+ }
+}
+
+// See https://github.com/golang/exp/blob/master/slog/benchmarks/benchmarks_test.go#L25
+//
+// Run e.g.:
+//
+// go test -bench=. -count=10 | benchstat -col /h /dev/stdin
+func BenchmarkLogAttrs(b *testing.B) {
+ handler := []struct {
+ Name string
+ H slog.Handler
+ }{
+ {"tint", tint.NewHandler(io.Discard, nil)},
+ {"text", slog.NewTextHandler(io.Discard, nil)},
+ {"json", slog.NewJSONHandler(io.Discard, nil)},
+ {"discard", new(discarder)},
+ }
+
+ benchmarks := []struct {
+ Name string
+ F func(*slog.Logger)
+ }{
+ {
+ "5 args",
+ func(logger *slog.Logger) {
+ logger.LogAttrs(context.TODO(), slog.LevelInfo, testMessage,
+ slog.String("string", testString),
+ slog.Int("status", testInt),
+ slog.Duration("duration", testDuration),
+ slog.Time("time", testTime),
+ slog.Any("error", errTest),
+ )
+ },
+ },
+ {
+ "5 args custom level",
+ func(logger *slog.Logger) {
+ logger.LogAttrs(context.TODO(), slog.LevelInfo+1, testMessage,
+ slog.String("string", testString),
+ slog.Int("status", testInt),
+ slog.Duration("duration", testDuration),
+ slog.Time("time", testTime),
+ slog.Any("error", errTest),
+ )
+ },
+ },
+ {
+ "10 args",
+ func(logger *slog.Logger) {
+ logger.LogAttrs(context.TODO(), slog.LevelInfo, testMessage,
+ slog.String("string", testString),
+ slog.Int("status", testInt),
+ slog.Duration("duration", testDuration),
+ slog.Time("time", testTime),
+ slog.Any("error", errTest),
+ slog.String("string", testString),
+ slog.Int("status", testInt),
+ slog.Duration("duration", testDuration),
+ slog.Time("time", testTime),
+ slog.Any("error", errTest),
+ )
+ },
+ },
+ {
+ "40 args",
+ func(logger *slog.Logger) {
+ logger.LogAttrs(context.TODO(), slog.LevelInfo, testMessage,
+ slog.String("string", testString),
+ slog.Int("status", testInt),
+ slog.Duration("duration", testDuration),
+ slog.Time("time", testTime),
+ slog.Any("error", errTest),
+ slog.String("string", testString),
+ slog.Int("status", testInt),
+ slog.Duration("duration", testDuration),
+ slog.Time("time", testTime),
+ slog.Any("error", errTest),
+ slog.String("string", testString),
+ slog.Int("status", testInt),
+ slog.Duration("duration", testDuration),
+ slog.Time("time", testTime),
+ slog.Any("error", errTest),
+ slog.String("string", testString),
+ slog.Int("status", testInt),
+ slog.Duration("duration", testDuration),
+ slog.Time("time", testTime),
+ slog.Any("error", errTest),
+ slog.String("string", testString),
+ slog.Int("status", testInt),
+ slog.Duration("duration", testDuration),
+ slog.Time("time", testTime),
+ slog.Any("error", errTest),
+ slog.String("string", testString),
+ slog.Int("status", testInt),
+ slog.Duration("duration", testDuration),
+ slog.Time("time", testTime),
+ slog.Any("error", errTest),
+ slog.String("string", testString),
+ slog.Int("status", testInt),
+ slog.Duration("duration", testDuration),
+ slog.Time("time", testTime),
+ slog.Any("error", errTest),
+ slog.String("string", testString),
+ slog.Int("status", testInt),
+ slog.Duration("duration", testDuration),
+ slog.Time("time", testTime),
+ slog.Any("error", errTest),
+ )
+ },
+ },
+ }
+
+ for _, h := range handler {
+ b.Run("h="+h.Name, func(b *testing.B) {
+ for _, bench := range benchmarks {
+ b.Run(bench.Name, func(b *testing.B) {
+ b.ReportAllocs()
+ logger := slog.New(h.H)
+ for i := 0; i < b.N; i++ {
+ bench.F(logger)
+ }
+ })
+ }
+ })
+ }
+}
+
+// discarder is a slog.Handler that discards all records.
+type discarder struct{}
+
+func (*discarder) Enabled(context.Context, slog.Level) bool { return true }
+func (*discarder) Handle(context.Context, slog.Record) error { return nil }
+func (d *discarder) WithAttrs(attrs []slog.Attr) slog.Handler { return d }
+func (d *discarder) WithGroup(name string) slog.Handler { return d }
+
+var (
+ testMessage = "Test logging, but use a somewhat realistic message length."
+ testTime = time.Date(2022, time.May, 1, 0, 0, 0, 0, time.UTC)
+ testString = "7e3b3b2aaeff56a7108fe11e154200dd/7819479873059528190"
+ testInt = 32768
+ testDuration = 23 * time.Second
+ errTest = errors.New("fail")
+)