feat: use Standard Go Project Layout as project structure template

pkg/config/Config.go

@@ -0,0 +1,33 @@
+package config
+
+import (
+	"github.com/ilyakaznacheev/cleanenv"
+	"sync"
+)
+
+type Config struct {
+	API struct {
+		Token string `env:"TOKEN" env-layout:"string" env-required:"true"`
+		Owner int    `env:"OWNER" env-layout:"int" env-required:"true"`
+	}
+	Paths struct {
+		Docs string `env:"DOCS_PATH" env-layout:"string" env-default:"docs" env-upd:"true"`
+	}
+}
+
+var (
+	cfg  Config    //nolint:gochecknoglobals // singleton globals
+	once sync.Once //nolint:gochecknoglobals // singleton globals
+)
+
+// GetConfig can panic
+func GetConfig() Config {
+	once.Do(func() {
+		err := cleanenv.ReadEnv(&cfg)
+		if err != nil {
+			panic(err)
+		}
+	})
+
+	return cfg
+}

pkg/config/Config_test.go

@@ -0,0 +1,99 @@
+package config
+
+import (
+	"github.com/stretchr/testify/assert"
+	"strconv"
+	"sync"
+	"testing"
+)
+
+const (
+	telegramToken    = ":: telegram telegram token ::" //nolint:gosec // it is not real credentials
+	telegramOwner    = 1234567890
+	pathDictionaries = `docs/dictionaries`
+)
+
+func TestGetConfig(t *testing.T) { //nolint:paralleltest // because this test mock globals
+	initTelegramBotEnvironment(t, telegramToken, telegramOwner, pathDictionaries)
+	defer resetConfig(t)
+
+	var config Config
+
+	assert.NotPanics(t, func() { config = GetConfig() })
+
+	assert.NotNil(t, config)
+	assert.Equal(t, telegramToken, config.API.Token)
+	assert.Equal(t, telegramOwner, config.API.Owner)
+	assert.Equal(t, pathDictionaries, config.Paths.Docs)
+}
+
+func TestGetConfigTwice(t *testing.T) { //nolint:paralleltest // because this test mock globals
+	initTelegramBotEnvironment(t, telegramToken, telegramOwner, pathDictionaries)
+	defer resetConfig(t)
+
+	config1 := GetConfig()
+	config2 := GetConfig()
+
+	assert.NotNil(t, config1)
+	assert.NotNil(t, config2)
+	assert.Equal(t, config1, config2)
+	assert.NotSame(t, config1, config2)
+}
+
+func TestGetConfigAndSingletonIsImmutable(t *testing.T) { //nolint:paralleltest // because this test mock globals
+	initTelegramBotEnvironment(t, telegramToken, telegramOwner, pathDictionaries)
+	defer resetConfig(t)
+
+	config1 := GetConfig()
+
+	assert.Equal(t, telegramToken, config1.API.Token)
+	assert.Equal(t, telegramOwner, config1.API.Owner)
+	assert.Equal(t, pathDictionaries, config1.Paths.Docs)
+
+	config1.API.Token = ":: some another telegram token ::"
+	config1.API.Owner = 1
+	config1.Paths.Docs = ":: some else path ::"
+	config2 := GetConfig()
+
+	assert.Equal(t, telegramToken, config2.API.Token)
+	assert.Equal(t, telegramOwner, config2.API.Owner)
+	assert.Equal(t, pathDictionaries, config2.Paths.Docs)
+}
+
+func TestGetConfigWithOnlyRequiredEnvironment(t *testing.T) { //nolint:paralleltest // because this test mock globals
+	t.Setenv("TOKEN", telegramToken)
+	t.Setenv("OWNER", strconv.Itoa(telegramOwner))
+
+	resetConfig(t)
+	defer resetConfig(t)
+
+	config := GetConfig()
+
+	assert.NotEmpty(t, config)
+	assert.IsType(t, Config{}, config)
+	assert.Equal(t, telegramToken, config.API.Token)
+	assert.Equal(t, telegramOwner, config.API.Owner)
+	assert.Equal(t, `docs`, config.Paths.Docs)
+}
+
+func TestGetConfigWithEmptyEnvironment(t *testing.T) { //nolint:paralleltest // because this test mock globals
+	resetConfig(t)
+	defer resetConfig(t)
+
+	assert.Panics(t, func() { GetConfig() })
+}
+
+func initTelegramBotEnvironment(t *testing.T, telegramToken string, telegramOwner int, pathDictionaries string) {
+	t.Helper()
+	t.Setenv("TOKEN", telegramToken)
+	t.Setenv("OWNER", strconv.Itoa(telegramOwner))
+	t.Setenv("DOCS_PATH", pathDictionaries)
+	resetConfig(t)
+}
+
+func resetConfig(t *testing.T) {
+	t.Helper()
+
+	cfg = Config{}
+	once = sync.Once{}
+}