fix panic at config root dir

Makefile

@@ -11,6 +11,10 @@ deps:
 zouch: $(shell find . -name "*.go")
 	go build -v
 
+.PHONY: test
+test: deps
+	go test -v ./...
+
 .PHONY: clean
 clean:
 	${RM} zouch

main.go

@@ -79,7 +79,7 @@ func runCommand(c *cli.Context) error {
 	}
 
 	logger := newLogger(verboseFlag)
-	rootDir := config.GetRootDir()
+	rootDir := config.NewConfig().RootDir()
 
 	app := newApp(logger, rootDir, createDirFlag, forceFlag)
 

pkg/config/config.go

@@ -6,22 +6,35 @@ import (
 )
 
 const (
-	rootEnvKey = "ZOUCH_ROOT"
+	RootEnvKey          = "ZOUCH_ROOT"
+	XdgConfigHomeEnvKey = "XDG_COFNIG_HOME"
 )
 
-func GetRootDir() string {
+type Config struct {
+	userHomeDir func() (string, error)
+	lookupEnv   func(key string) (string, bool)
+}
+
+func NewConfig() *Config {
+	return &Config{
+		userHomeDir: os.UserHomeDir,
+		lookupEnv:   os.LookupEnv,
+	}
+}
+
+func (c *Config) RootDir() string {
 	// "$ZOUCH_ROOT"
-	if root, ok := os.LookupEnv(rootEnvKey); ok {
+	if root, ok := c.lookupEnv(RootEnvKey); ok {
 		return root
 	}
 	// "$XDG_CONFIG_HOME/zouch"
-	if xdgConfigHome, ok := os.LookupEnv("XDG_CONFIG_HOME"); ok {
+	if xdgConfigHome, ok := c.lookupEnv(XdgConfigHomeEnvKey); ok {
 		return path.Join(xdgConfigHome, "zouch")
 	}
 	// "$HOME/.config/zouch"
-	home, err := os.UserHomeDir()
+	home, err := c.userHomeDir()
 	if err != nil {
-		return path.Join(home, ".config", "zouch")
+		panic(err)
 	}
-	panic(err)
+	return path.Join(home, ".config", "zouch")
 }

pkg/config/config_test.go

@@ -0,0 +1,74 @@
+package config
+
+import (
+	"testing"
+)
+
+func TestRootDir(t *testing.T) {
+	type envs struct {
+		home          string
+		xdgConfigHome string
+		zouchRoot     string
+	}
+	type scenario struct {
+		expectedRootDir string
+		envs            envs
+	}
+
+	scenarios := []scenario{
+		{
+			expectedRootDir: "/home/USER/.config/zouch",
+			envs: envs{
+				home:          "/home/USER",
+				xdgConfigHome: "",
+				zouchRoot:     "",
+			},
+		},
+		{
+			expectedRootDir: "/home/USER/xdgConfig/zouch",
+			envs: envs{
+				home:          "/home/USER",
+				xdgConfigHome: "/home/USER/xdgConfig",
+				zouchRoot:     "",
+			},
+		},
+		{
+			expectedRootDir: "/tmp/zouch",
+			envs: envs{
+				home:          "/home/USER",
+				xdgConfigHome: "/home/USER/xdgConfig",
+				zouchRoot:     "/tmp/zouch",
+			},
+		},
+	}
+
+	for _, s := range scenarios {
+		t.Run(s.expectedRootDir, func(t *testing.T) {
+			c := newTestConfig(s.envs.home, s.envs.xdgConfigHome, s.envs.zouchRoot)
+
+			if rootDir := c.RootDir(); rootDir != s.expectedRootDir {
+				t.Fatalf("expected rootDir == %v, actual %v", s.expectedRootDir, rootDir)
+			}
+		})
+	}
+}
+
+func newTestConfig(home string, xdgConfigHome string, zouchRoot string) *Config {
+	return &Config{
+		// Stub of os.UserHomeDir
+		userHomeDir: func() (string, error) {
+			return home, nil
+		},
+		// Stub of os.LookupEnv
+		lookupEnv: func(key string) (string, bool) {
+			switch key {
+			case XdgConfigHomeEnvKey:
+				return xdgConfigHome, len(xdgConfigHome) > 0
+			case RootEnvKey:
+				return zouchRoot, len(zouchRoot) > 0
+			default:
+				return "", false
+			}
+		},
+	}
+}