SugaredLogger: Add WithOptions (#1079)

Add a WithOptions method to SugaredLogger that allows specifying
building a copy of the logger with the specified options applied.

This allows turning,

    slog.Desugar().WithOptions(...).Sugar()

Into,

    slog.WithOptions(...)

Closes #1072

sugar.go

@@ -61,6 +61,16 @@ func (s *SugaredLogger) Named(name string) *SugaredLogger {
 	return &SugaredLogger{base: s.base.Named(name)}
 }
 
+// WithOptions clones the current SugaredLogger, applies the supplied Options,
+// and returns the result. It's safe to use concurrently.
+func (s *SugaredLogger) WithOptions(opts ...Option) *SugaredLogger {
+	base := s.base.clone()
+	for _, opt := range opts {
+		opt.apply(base)
+	}
+	return &SugaredLogger{base: base}
+}
+
 // With adds a variadic number of fields to the logging context. It accepts a
 // mix of strongly-typed Field objects and loosely-typed key-value pairs. When
 // processing pairs, the first element of the pair is used as the field key

sugar_test.go

@@ -369,6 +369,22 @@ func TestSugarAddCallerFail(t *testing.T) {
 	})
 }
 
+func TestSugarWithOptionsIncreaseLevel(t *testing.T) {
+	withSugar(t, DebugLevel, nil, func(logger *SugaredLogger, logs *observer.ObservedLogs) {
+		logger = logger.WithOptions(IncreaseLevel(WarnLevel))
+		logger.Info("logger.Info")
+		logger.Warn("logger.Warn")
+		logger.Error("logger.Error")
+		require.Equal(t, 2, logs.Len(), "expected only warn + error logs due to IncreaseLevel.")
+		assert.Equal(
+			t,
+			logs.AllUntimed()[0].Message,
+			"logger.Warn",
+			"Expected first logged message to be warn level message",
+		)
+	})
+}
+
 func BenchmarkSugarSingleStrArg(b *testing.B) {
 	withSugar(b, InfoLevel, nil /* opts* */, func(log *SugaredLogger, logs *observer.ObservedLogs) {
 		for i := 0; i < b.N; i++ {