Updating SafeWriteConfig and SafeWriteConfigAs to match documented be…

viper.go

@@ -23,6 +23,7 @@ import (
 	"bytes"
 	"encoding/csv"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -115,6 +116,14 @@ func (fnfe ConfigFileNotFoundError) Error() string {
 	return fmt.Sprintf("Config File %q Not Found in %q", fnfe.name, fnfe.locations)
 }
 
+// ConfigFileAlreadyExistsError denotes failure to write new configuration file.
+type ConfigFileAlreadyExistsError string
+
+// Error returns the formatted error when configuration already exists.
+func (faee ConfigFileAlreadyExistsError) Error() string {
+	return fmt.Sprintf("Config File %q Already Exists", string(faee))
+}
+
 // A DecoderConfigOption can be passed to viper.Unmarshal to configure
 // mapstructure.DecoderConfig options
 type DecoderConfigOption func(*mapstructure.DecoderConfig)
@@ -1331,11 +1340,10 @@ func (v *Viper) WriteConfig() error {
 // SafeWriteConfig writes current configuration to file only if the file does not exist.
 func SafeWriteConfig() error { return v.SafeWriteConfig() }
 func (v *Viper) SafeWriteConfig() error {
-	filename, err := v.getConfigFile()
-	if err != nil {
-		return err
+	if len(v.configPaths) < 1 {
+		return errors.New("Missing configuration for 'configPath'")
 	}
-	return v.writeConfig(filename, false)
+	return v.SafeWriteConfigAs(filepath.Join(v.configPaths[0], v.configName+"."+v.configType))
 }
 
 // WriteConfigAs writes current configuration to a given filename.
@@ -1347,6 +1355,10 @@ func (v *Viper) WriteConfigAs(filename string) error {
 // SafeWriteConfigAs writes current configuration to a given filename if it does not exist.
 func SafeWriteConfigAs(filename string) error { return v.SafeWriteConfigAs(filename) }
 func (v *Viper) SafeWriteConfigAs(filename string) error {
+	alreadyExists, err := afero.Exists(v.fs, filename)
+	if alreadyExists && err == nil {
+		return ConfigFileAlreadyExistsError(filename)
+	}
 	return v.writeConfig(filename, false)
 }
 

viper_test.go

@@ -1349,6 +1349,68 @@ func TestWriteConfigYAML(t *testing.T) {
 	assert.Equal(t, yamlWriteExpected, read)
 }
 
+func TestSafeWriteConfig(t *testing.T) {
+	v := New()
+	fs := afero.NewMemMapFs()
+	v.SetFs(fs)
+	v.AddConfigPath("/test")
+	v.SetConfigName("c")
+	v.SetConfigType("yaml")
+	require.NoError(t, v.ReadConfig(bytes.NewBuffer(yamlExample)))
+	require.NoError(t, v.SafeWriteConfig())
+	read, err := afero.ReadFile(fs, "/test/c.yaml")
+	require.NoError(t, err)
+	assert.Equal(t, yamlWriteExpected, read)
+}
+
+func TestSafeWriteConfigWithMissingConfigPath(t *testing.T) {
+	v := New()
+	fs := afero.NewMemMapFs()
+	v.SetFs(fs)
+	v.SetConfigName("c")
+	v.SetConfigType("yaml")
+	require.EqualError(t, v.SafeWriteConfig(), "Missing configuration for 'configPath'")
+}
+
+func TestSafeWriteConfigWithExistingFile(t *testing.T) {
+	v := New()
+	fs := afero.NewMemMapFs()
+	fs.Create("/test/c.yaml")
+	v.SetFs(fs)
+	v.AddConfigPath("/test")
+	v.SetConfigName("c")
+	v.SetConfigType("yaml")
+	err := v.SafeWriteConfig()
+	require.Error(t, err)
+	_, ok := err.(ConfigFileAlreadyExistsError)
+	assert.True(t, ok, "Expected ConfigFileAlreadyExistsError")
+}
+
+func TestSafeWriteAsConfig(t *testing.T) {
+	v := New()
+	fs := afero.NewMemMapFs()
+	v.SetFs(fs)
+	err := v.ReadConfig(bytes.NewBuffer(yamlExample))
+	if err != nil {
+		t.Fatal(err)
+	}
+	require.NoError(t, v.SafeWriteConfigAs("/test/c.yaml"))
+	if _, err = afero.ReadFile(fs, "/test/c.yaml"); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestSafeWriteConfigAsWithExistingFile(t *testing.T) {
+	v := New()
+	fs := afero.NewMemMapFs()
+	fs.Create("/test/c.yaml")
+	v.SetFs(fs)
+	err := v.SafeWriteConfigAs("/test/c.yaml")
+	require.Error(t, err)
+	_, ok := err.(ConfigFileAlreadyExistsError)
+	assert.True(t, ok, "Expected ConfigFileAlreadyExistsError")
+}
+
 var yamlMergeExampleTgt = []byte(`
 hello:
     pop: 37890