Change LogLevel to satisfy flag.Value interface

internal/log/log.go

@@ -13,7 +13,7 @@ import (
 	"sync"
 )
 
-// Base supports logging with various log levels.
+// Base supports logging at various log levels.
 type Base interface {
 	// Debug logs a message at Debug level.
 	Debug(args ...interface{})
@@ -87,7 +87,7 @@ func NewLogger(base Base) *Logger {
 	return &Logger{base: base, level: DebugLevel}
 }
 
-// Logger logs message to io.Writer with various log levels.
+// Logger logs message to io.Writer at various log levels.
 type Logger struct {
 	base Base
 
@@ -121,6 +121,9 @@ const (
 	FatalLevel
 )
 
+// String is part of the fmt.Stringer interface.
+//
+// Used for testing and debugging purposes.
 func (l Level) String() string {
 	switch l {
 	case DebugLevel:
@@ -167,14 +170,14 @@ func (l *Logger) Warn(args ...interface{}) {
 }
 
 func (l *Logger) Error(args ...interface{}) {
-	if !l.canLogAt(WarnLevel) {
+	if !l.canLogAt(ErrorLevel) {
 		return
 	}
 	l.base.Error(args...)
 }
 
 func (l *Logger) Fatal(args ...interface{}) {
-	if !l.canLogAt(WarnLevel) {
+	if !l.canLogAt(FatalLevel) {
 		return
 	}
 	l.base.Fatal(args...)

internal/log/log_test.go

@@ -284,7 +284,9 @@ func TestLoggerErrorf(t *testing.T) {
 	}
 }
 
-func TestLoggerWithMinLevels(t *testing.T) {
+func TestLoggerWithLowerLevels(t *testing.T) {
+	// Logger should not log messages at a level
+	// lower than the specified level.
 	tests := []struct {
 		level Level
 		op    string
@@ -334,3 +336,53 @@ func TestLoggerWithMinLevels(t *testing.T) {
 		}
 	}
 }
+
+func TestLoggerWithSameOrHigherLevels(t *testing.T) {
+	// Logger should log messages at a level
+	// same as or higher than the specified level.
+	tests := []struct {
+		level Level
+		op    string
+	}{
+		// same level
+		{DebugLevel, "Debug"},
+		{InfoLevel, "Infof"},
+		{WarnLevel, "Warn"},
+		{ErrorLevel, "Errorf"},
+		// higher level
+		{DebugLevel, "Info"},
+		{InfoLevel, "Warnf"},
+		{WarnLevel, "Error"},
+	}
+
+	for _, tc := range tests {
+		var buf bytes.Buffer
+		logger := NewLogger(newBase(&buf))
+		logger.SetLevel(tc.level)
+
+		switch tc.op {
+		case "Debug":
+			logger.Debug("hello")
+		case "Debugf":
+			logger.Debugf("hello, %s", "world")
+		case "Info":
+			logger.Info("hello")
+		case "Infof":
+			logger.Infof("hello, %s", "world")
+		case "Warn":
+			logger.Warn("hello")
+		case "Warnf":
+			logger.Warnf("hello, %s", "world")
+		case "Error":
+			logger.Error("hello")
+		case "Errorf":
+			logger.Errorf("hello, %s", "world")
+		default:
+			t.Fatalf("unexpected op: %q", tc.op)
+		}
+
+		if buf.String() == "" {
+			t.Errorf("logger.%s did not output log message when level is set to %v", tc.op, tc.level)
+		}
+	}
+}