WriteConfig does not fail on unknown file extensions when the config …

…type is set

viper.go

@@ -1411,7 +1411,7 @@ func (v *Viper) WriteConfig() error {
 	if err != nil {
 		return err
 	}
-	return v.writeConfig(filename, true)
+	return v.writeConfig(filename, v.getConfigType(), true)
 }
 
 // SafeWriteConfig writes current configuration to file only if the file does not exist.
@@ -1426,7 +1426,7 @@ func (v *Viper) SafeWriteConfig() error {
 // WriteConfigAs writes current configuration to a given filename.
 func WriteConfigAs(filename string) error { return v.WriteConfigAs(filename) }
 func (v *Viper) WriteConfigAs(filename string) error {
-	return v.writeConfig(filename, true)
+	return v.writeConfig(filename, filepath.Ext(filename), true)
 }
 
 // SafeWriteConfigAs writes current configuration to a given filename if it does not exist.
@@ -1436,22 +1436,11 @@ func (v *Viper) SafeWriteConfigAs(filename string) error {
 	if alreadyExists && err == nil {
 		return ConfigFileAlreadyExistsError(filename)
 	}
-	return v.writeConfig(filename, false)
+	return v.writeConfig(filename, filepath.Ext(filename), false)
 }
 
-func (v *Viper) writeConfig(filename string, force bool) error {
+func (v *Viper) writeConfig(filename string, configType string, force bool) error {
 	jww.INFO.Println("Attempting to write configuration to file.")
-	var configType string
-
-	ext := filepath.Ext(filename)
-	if ext != "" {
-		configType = ext[1:]
-	} else {
-		configType = v.configType
-	}
-	if configType == "" {
-		return fmt.Errorf("config type could not be determined for %s", filename)
-	}
 
 	if !stringInSlice(configType, SupportedExts) {
 		return UnsupportedConfigError(configType)