[log] add NewFilterByLevel helper func

log/filter.go

@@ -1,5 +1,7 @@
 package log
 
+import "fmt"
+
 // NewFilter wraps next and implements filtering. See the commentary on the
 // Option functions for a detailed description of how to configure levels. If
 // no options are provided, all leveled log events created with Debug, Info or
@@ -14,6 +16,22 @@ func NewFilter(next Logger, options ...Option) Logger {
 	return l
 }
 
+// NewFilterByLevel wraps next and implements filtering based on a given level.
+func NewFilterByLevel(next Logger, lvl string) Logger {
+	var option Option
+	switch lvl {
+	case "info":
+		option = AllowInfo()
+	case "debug":
+		option = AllowDebug()
+	case "error":
+		option = AllowError()
+	default:
+		panic(fmt.Sprintf("Expected either \"info\", \"debug\" or \"error\" log level, given %v", lvl))
+	}
+	return NewFilter(next, option)
+}
+
 type filter struct {
 	next          Logger
 	allowed       level

log/filter_test.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
 	"github.com/tendermint/tmlibs/log"
 )
 
@@ -107,3 +108,15 @@ func TestLevelContext(t *testing.T) {
 		t.Errorf("\nwant '%s'\nhave '%s'", want, have)
 	}
 }
+
+func TestNewFilterByLevel(t *testing.T) {
+	assert := assert.New(t)
+	var logger log.Logger
+	logger = log.NewNopLogger()
+	assert.NotPanics(func() {
+		logger = log.NewFilterByLevel(logger, "info")
+	})
+	assert.Panics(func() {
+		logger = log.NewFilterByLevel(logger, "smth")
+	})
+}