Initialize the configuration file during writing if not exist

viper.go

@@ -1316,7 +1316,15 @@ func WriteConfig() error { return v.WriteConfig() }
 func (v *Viper) WriteConfig() error {
 	filename, err := v.getConfigFile()
 	if err != nil {
-		return err
+		ext := SupportedExts[0]
+		if v.configType != "" {
+			ext = v.configType
+		}
+		path := ""
+		if len(v.configPaths) > 0 {
+			path = v.configPaths[0]
+		}
+		filename = filepath.Join(path, v.configName+"."+ext)
 	}
 	return v.writeConfig(filename, true)
 }
@@ -1326,7 +1334,15 @@ func SafeWriteConfig() error { return v.SafeWriteConfig() }
 func (v *Viper) SafeWriteConfig() error {
 	filename, err := v.getConfigFile()
 	if err != nil {
-		return err
+		ext := SupportedExts[0]
+		if v.configType != "" {
+			ext = v.configType
+		}
+		path := ""
+		if len(v.configPaths) > 0 {
+			path = v.configPaths[0]
+		}
+		filename = filepath.Join(path, v.configName+"."+ext)
 	}
 	return v.writeConfig(filename, false)
 }

viper_test.go

@@ -1243,6 +1243,26 @@ func TestWriteConfigYAML(t *testing.T) {
 	assert.Equal(t, yamlWriteExpected, read)
 }
 
+func TestWriteNotExistTarget(t *testing.T) {
+	v := New()
+	fs := afero.NewMemMapFs()
+	v.SetFs(fs)
+	v.SetConfigName("c")
+	v.SetConfigType("yaml")
+	err := v.ReadConfig(bytes.NewBuffer(yamlExample))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := v.WriteConfig(); err != nil {
+		t.Fatal(err)
+	}
+	read, err := afero.ReadFile(fs, "c.yaml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	assert.Equal(t, yamlWriteExpected, read)
+}
+
 var yamlMergeExampleTgt = []byte(`
 hello:
     pop: 37890