Fix WriteConfig (#430, #433)

viper.go

@@ -190,8 +190,11 @@ type Viper struct {
 	remoteProviders []*defaultRemoteProvider
 
 	// Name of file to look for inside the path
-	configName        string
+	configName string
-	configFile        string
+	configFile struct {
+		path          string
+		explicitlySet bool
+	}
 	configType        string
 	configPermissions os.FileMode
 	envPrefix         string
@@ -411,7 +414,8 @@ func (v *Viper) WatchConfig() {
 func SetConfigFile(in string) { v.SetConfigFile(in) }
 func (v *Viper) SetConfigFile(in string) {
 	if in != "" {
-		v.configFile = in
+		v.configFile.path = in
+		v.configFile.explicitlySet = true
 	}
 }
 
@@ -460,7 +464,7 @@ func (v *Viper) getEnv(key string) (string, bool) {
 
 // ConfigFileUsed returns the file used to populate the config registry.
 func ConfigFileUsed() string            { return v.ConfigFileUsed() }
-func (v *Viper) ConfigFileUsed() string { return v.configFile }
+func (v *Viper) ConfigFileUsed() string { return v.configFile.path }
 
 // AddConfigPath adds a path for Viper to search for the config file in.
 // Can be called multiple times to define multiple search paths.
@@ -1407,20 +1411,32 @@ func (v *Viper) MergeConfigMap(cfg map[string]interface{}) error {
 // WriteConfig writes the current configuration to a file.
 func WriteConfig() error { return v.WriteConfig() }
 func (v *Viper) WriteConfig() error {
-	filename, err := v.getConfigFile()
+	if !v.configFile.explicitlySet {
-	if err != nil {
+		_, err := v.getConfigFile()
-		return err
+		if err != nil {
+			if _, ok := err.(ConfigFileNotFoundError); ok {
+				if len(v.configPaths) < 1 {
+					return errors.New("missing configuration for 'configPath'")
+				}
+				v.configFile.path = filepath.Join(v.configPaths[0], v.configName+"."+v.configType)
+			} else {
+				return err
+			}
+		}
 	}
-	return v.writeConfig(filename, true)
+	return v.WriteConfigAs(v.configFile.path)
 }
 
 // SafeWriteConfig writes current configuration to file only if the file does not exist.
 func SafeWriteConfig() error { return v.SafeWriteConfig() }
 func (v *Viper) SafeWriteConfig() error {
-	if len(v.configPaths) < 1 {
+	if !v.configFile.explicitlySet {
-		return errors.New("missing configuration for 'configPath'")
+		if len(v.configPaths) < 1 {
+			return errors.New("missing configuration for 'configPath'")
+		}
+		v.configFile.path = filepath.Join(v.configPaths[0], v.configName+"."+v.configType)
 	}
-	return v.SafeWriteConfigAs(filepath.Join(v.configPaths[0], v.configName+"."+v.configType))
+	return v.SafeWriteConfigAs(v.configFile.path)
 }
 
 // WriteConfigAs writes current configuration to a given filename.
@@ -1947,7 +1963,8 @@ func SetConfigName(in string) { v.SetConfigName(in) }
 func (v *Viper) SetConfigName(in string) {
 	if in != "" {
 		v.configName = in
-		v.configFile = ""
+		v.configFile.path = ""
+		v.configFile.explicitlySet = false
 	}
 }
 
@@ -1986,14 +2003,14 @@ func (v *Viper) getConfigType() string {
 }
 
 func (v *Viper) getConfigFile() (string, error) {
-	if v.configFile == "" {
+	if v.configFile.path == "" {
 		cf, err := v.findConfigFile()
 		if err != nil {
 			return "", err
 		}
-		v.configFile = cf
+		v.configFile.path = cf
 	}
-	return v.configFile, nil
+	return v.configFile.path, nil
 }
 
 func (v *Viper) searchInPath(in string) (filename string) {

viper_test.go

@@ -1372,7 +1372,7 @@ hobbies:
 name: steve
 `)
 
-func TestWriteConfig(t *testing.T) {
+func TestWriteConfigAs(t *testing.T) {
 	fs := afero.NewMemMapFs()
 	testCases := map[string]struct {
 		configName      string
@@ -1495,7 +1495,7 @@ func TestWriteConfig(t *testing.T) {
 	}
 }
 
-func TestWriteConfigTOML(t *testing.T) {
+func TestWriteConfigAsTOML(t *testing.T) {
 	fs := afero.NewMemMapFs()
 
 	testCases := map[string]struct {
@@ -1551,7 +1551,7 @@ func TestWriteConfigTOML(t *testing.T) {
 	}
 }
 
-func TestWriteConfigDotEnv(t *testing.T) {
+func TestWriteConfigAsDotEnv(t *testing.T) {
 	fs := afero.NewMemMapFs()
 	testCases := map[string]struct {
 		configName string
@@ -1605,6 +1605,56 @@ func TestWriteConfigDotEnv(t *testing.T) {
 	}
 }
 
+func TestWriteConfig(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.WriteConfig())
+	read, err := afero.ReadFile(fs, "/test/c.yaml")
+	require.NoError(t, err)
+	assert.Equal(t, yamlWriteExpected, read)
+}
+
+func TestWriteConfigWithExplicitlySetFile(t *testing.T) {
+	v := New()
+	fs := afero.NewMemMapFs()
+	v.SetFs(fs)
+	v.AddConfigPath("/test1")
+	v.SetConfigName("c1")
+	v.SetConfigType("yaml")
+	v.SetConfigFile("/test2/c2.yaml")
+	require.NoError(t, v.ReadConfig(bytes.NewBuffer(yamlExample)))
+	require.NoError(t, v.WriteConfig())
+	read, err := afero.ReadFile(fs, "/test2/c2.yaml")
+	require.NoError(t, err)
+	assert.Equal(t, yamlWriteExpected, read)
+}
+
+func TestWriteConfigWithMissingConfigPath(t *testing.T) {
+	v := New()
+	fs := afero.NewMemMapFs()
+	v.SetFs(fs)
+	v.SetConfigName("c")
+	v.SetConfigType("yaml")
+	require.EqualError(t, v.WriteConfig(), "missing configuration for 'configPath'")
+}
+
+func TestWriteConfigWithExistingFile(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.WriteConfig()
+	require.NoError(t, err)
+}
+
 func TestSafeWriteConfig(t *testing.T) {
 	v := New()
 	fs := afero.NewMemMapFs()
@@ -1619,6 +1669,21 @@ func TestSafeWriteConfig(t *testing.T) {
 	assert.Equal(t, yamlWriteExpected, read)
 }
 
+func TestSafeWriteConfigWithExplicitlySetFile(t *testing.T) {
+	v := New()
+	fs := afero.NewMemMapFs()
+	v.SetFs(fs)
+	v.AddConfigPath("/test1")
+	v.SetConfigName("c1")
+	v.SetConfigType("yaml")
+	v.SetConfigFile("/test2/c2.yaml")
+	require.NoError(t, v.ReadConfig(bytes.NewBuffer(yamlExample)))
+	require.NoError(t, v.SafeWriteConfig())
+	read, err := afero.ReadFile(fs, "/test2/c2.yaml")
+	require.NoError(t, err)
+	assert.Equal(t, yamlWriteExpected, read)
+}
+
 func TestSafeWriteConfigWithMissingConfigPath(t *testing.T) {
 	v := New()
 	fs := afero.NewMemMapFs()
@@ -1642,7 +1707,7 @@ func TestSafeWriteConfigWithExistingFile(t *testing.T) {
 	assert.True(t, ok, "Expected ConfigFileAlreadyExistsError")
 }
 
-func TestSafeWriteAsConfig(t *testing.T) {
+func TestSafeWriteConfigAs(t *testing.T) {
 	v := New()
 	fs := afero.NewMemMapFs()
 	v.SetFs(fs)