chore(logger): move logger to internal

This commit moves logger to internal package.

Follow up to #1977

Signed-off-by: vprashar2929 <[email protected]>

Author: vprashar2929

cmd/kepler/main.go

@@ -13,6 +13,7 @@ import (
 	"github.com/alecthomas/kingpin/v2"
 	"github.com/oklog/run"
 	"github.com/sustainable-computing-io/kepler/internal/config"
+	"github.com/sustainable-computing-io/kepler/internal/logger"
 	"github.com/sustainable-computing-io/kepler/internal/version"
 )
 
@@ -22,7 +23,7 @@ func main() {
 	if err != nil {
 		os.Exit(1)
 	}
-	logger := setupLogger(cfg.Log.Level, cfg.Log.Format)
+	logger := logger.New(cfg.Log.Level, cfg.Log.Format)
 	logVersionInfo(logger)
 	printConfigInfo(logger, cfg)
 
@@ -110,7 +111,7 @@ func parseArgsAndConfig() (*config.Config, error) {
 	updateConfig := config.RegisterFlags(app)
 	kingpin.MustParse(app.Parse(os.Args[1:]))
 
-	logger := setupLogger("info", "text")
+	logger := logger.New("info", "text")
 	cfg := config.DefaultConfig()
 	if *configFile != "" {
 		logger.Info("Loading configuration file", "path", *configFile)

cmd/kepler/logger.go renamed to internal/logger/logger.go

@@ -1,7 +1,7 @@
 // SPDX-FileCopyrightText: 2025 The Kepler Authors
 // SPDX-License-Identifier: Apache-2.0
 
-package main
+package logger
 
 import (
 	"fmt"
@@ -11,7 +11,7 @@ import (
 	"strings"
 )
 
-func setupLogger(level, format string) *slog.Logger {
+func New(level, format string) *slog.Logger {
 	logLevel := parseLogLevel(level)
 	return slog.New(handlerForFormat(format, logLevel))
 }

cmd/kepler/logger_test.go renamed to internal/logger/logger_test.go

@@ -1,11 +1,12 @@
 // SPDX-FileCopyrightText: 2025 The Kepler Authors
 // SPDX-License-Identifier: Apache-2.0
 
-package main
+package logger
 
 import (
 	"bytes"
 	"encoding/json"
+	"log/slog"
 	"os"
 	"strings"
 	"testing"
@@ -65,7 +66,7 @@ func TestSetupLogger(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			if tt.expectPanic {
 				assert.Panics(t, func() {
-					_ = setupLogger(tt.format, tt.logLevel)
+					_ = New(tt.logLevel, tt.format)
 				}, "Expected setupLogger to panic with invalid format")
 				//
 				return
@@ -77,7 +78,7 @@ func TestSetupLogger(t *testing.T) {
 			r, w, _ := os.Pipe()
 			os.Stdout = w
 
-			logger := setupLogger(tt.logLevel, tt.format)
+			logger := New(tt.logLevel, tt.format)
 			logger.Info("test message", "key", "value")
 
 			// Restore stdout
@@ -120,3 +121,49 @@ func TestSetupLogger(t *testing.T) {
 		})
 	}
 }
+
+func TestParseLogLevel(t *testing.T) {
+	tests := []struct {
+		name     string
+		level    string
+		expected slog.Level
+	}{
+		{
+			name:     "debug level",
+			level:    "debug",
+			expected: slog.LevelDebug,
+		},
+		{
+			name:     "info level",
+			level:    "info",
+			expected: slog.LevelInfo,
+		},
+		{
+			name:     "warn level",
+			level:    "warn",
+			expected: slog.LevelWarn,
+		},
+		{
+			name:     "error level",
+			level:    "error",
+			expected: slog.LevelError,
+		},
+		{
+			name:     "invalid level defaults to info",
+			level:    "invalid",
+			expected: slog.LevelInfo,
+		},
+		{
+			name:     "empty level defaults to info",
+			level:    "",
+			expected: slog.LevelInfo,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := parseLogLevel(tt.level)
+			assert.Equal(t, tt.expected, result, "parseLogLevel(%q) = %v, want %v", tt.level, result, tt.expected)
+		})
+	}
+}