config_file.go: Parameterise filename for unit testing (fix oz#68)

config.go

@@ -58,9 +58,17 @@ var DefaultKeymaps = Keymaps{
 	Quit:       []string{"q", "ctrl+c", "esc"},
 }
 
-func LoadConfig(tzConfigs []string) (*Config, error) {
+func LoadDefaultConfig(tzConfigs []string) (*Config, error) {
+	fileName, fileError := DefaultConfigFile()
+	if fileError != nil {
+		return nil, fmt.Errorf("File error: %w", fileError)
+	}
+	return LoadConfig(*fileName, tzConfigs)
+}
+
+func LoadConfig(tomlFile string, tzConfigs []string) (*Config, error) {
 	// Apply config file first
-	fileConfig, fileError := LoadConfigFile()
+	fileConfig, fileError := LoadConfigFile(tomlFile)
 	if fileError != nil {
 		return nil, fmt.Errorf("File error: %w", fileError)
 	}

config_file.go

@@ -56,16 +56,20 @@ func ReadZonesFromFile(now time.Time, zoneConf ConfigFileZone) (*Zone, error) {
 	}, nil
 }
 
-func LoadConfigFile() (*Config, error) {
-	conf := Config{}
-
+func DefaultConfigFile() (*string, error) {
 	// Return early if we can't find a home dir.
 	homeDir, err := os.UserHomeDir()
 	if err != nil {
-		return &conf, nil
+		return nil, err
 	}
 
 	configFilePath := filepath.Join(homeDir, ".config", "tz", "conf.toml")
+	return &configFilePath, nil
+}
+
+func LoadConfigFile(configFilePath string) (*Config, error) {
+	conf := Config{}
+
 	configFile, err := os.ReadFile(configFilePath)
 	if err != nil {
 		// Ignore unreadable config file.

main.go

@@ -174,7 +174,7 @@ func main() {
 		os.Exit(0)
 	}
 
-	config, err := LoadConfig(flag.Args())
+	config, err := LoadDefaultConfig(flag.Args())
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "Config error: %s\n", err)
 		os.Exit(2)