Fix attrs being silently dropped on child loggers (#33)

* Fix attrs being silently dropped on child loggers

* Clean up un-needed nil

Author: FollowTheProcess

Taskfile.yml

@@ -69,7 +69,7 @@ tasks:
       - .golangci.yml
     preconditions:
       - sh: command -v golangci-lint
-        msg: staticcheck not installed, run `brew install golangci-lint`
+        msg: golangci-lint not installed, run `brew install golangci-lint`
 
       - sh: command -v typos
         msg: requires typos-cli, run `brew install typos-cli`

log.go

@@ -178,6 +178,7 @@ func (l *Logger) clone() *Logger {
 		timeFunc:   l.timeFunc,
 		timeFormat: l.timeFormat,
 		prefix:     l.prefix,
+		attrs:      l.attrs,
 		level:      l.level,
 		mu:         l.mu,
 	}
@@ -216,8 +217,7 @@ func putBuffer(buf *bytes.Buffer) {
 	// Approx 65kb
 	const maxSize = 64 << 10
 	if buf.Cap() > maxSize {
-		// Make the buffer nil so GC cleans it up
-		buf = nil
+		return
 	}
 
 	bufPool.Put(buf)

log_test.go

@@ -147,6 +147,8 @@ func TestDebug(t *testing.T) {
 }
 
 func TestWith(t *testing.T) {
+	hue.Enabled(false) // Force no color
+
 	// Constantly return the same time
 	fixedTime := func() time.Time {
 		fixed, err := time.Parse(time.RFC3339, "2025-04-01T13:34:03Z")
@@ -157,24 +159,67 @@ func TestWith(t *testing.T) {
 
 	fixedTimeString := fixedTime().Format(time.RFC3339)
 
-	buf := &bytes.Buffer{}
-
-	logger := log.New(buf, log.TimeFunc(fixedTime))
-
-	logger.Info("I'm an info message")
-
-	sub := logger.With(
-		slog.Bool("sub", true),
-		slog.String("hello", "world"),
-	)
+	tests := []struct {
+		name string
+		fn   func() string // Exercise the logger, return output
+		want string
+	}{
+		{
+			name: "attrs appear on sub logger",
+			fn: func() string {
+				buf := &bytes.Buffer{}
+				l := log.New(buf, log.TimeFunc(fixedTime))
+				l.Info("I'm an info message")
+				sub := l.With(slog.Bool("sub", true), slog.String("hello", "world"))
+				sub.Info("I'm also an info message")
+
+				return buf.String()
+			},
+			want: "[TIME] INFO:  I'm an info message\n[TIME] INFO:  I'm also an info message sub=true hello=world\n",
+		},
+		{
+			name: "chained With preserves earlier attrs",
+			fn: func() string {
+				buf := &bytes.Buffer{}
+				l := log.New(buf, log.TimeFunc(fixedTime))
+				l.With(slog.String("a", "1")).With(slog.String("b", "2")).Info("chained")
 
-	sub.Info("I'm also an info message")
+				return buf.String()
+			},
+			want: "[TIME] INFO:  chained a=1 b=2\n",
+		},
+		{
+			name: "Prefixed preserves attrs from With",
+			fn: func() string {
+				buf := &bytes.Buffer{}
+				l := log.New(buf, log.TimeFunc(fixedTime))
+				l.With(slog.String("a", "1")).Prefixed("svc").Info("prefixed")
 
-	got := buf.String()
-	got = strings.TrimSpace(strings.ReplaceAll(got, fixedTimeString, "[TIME]")) + "\n"
+				return buf.String()
+			},
+			want: "[TIME] INFO svc:  prefixed a=1\n",
+		},
+		{
+			name: "parent logger not affected by child With",
+			fn: func() string {
+				buf := &bytes.Buffer{}
+				l := log.New(buf, log.TimeFunc(fixedTime))
+				_ = l.With(slog.String("child", "attr"))
+				l.Info("parent should have no attrs")
+
+				return buf.String()
+			},
+			want: "[TIME] INFO:  parent should have no attrs\n",
+		},
+	}
 
-	want := "[TIME] INFO:  I'm an info message\n[TIME] INFO:  I'm also an info message sub=true hello=world\n"
-	test.Diff(t, got, want)
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := tt.fn()
+			got = strings.ReplaceAll(got, fixedTimeString, "[TIME]")
+			test.Diff(t, got, tt.want)
+		})
+	}
 }
 
 func TestRace(t *testing.T) {