From a3d17c7a2036afca430a814c641dc8c24b418f88 Mon Sep 17 00:00:00 2001
From: Ryan SIU <ryan.siu@cloverhealth.com>
Date: Fri, 26 Jul 2019 14:01:37 +0800
Subject: [PATCH] Initialize the configuration file during writing if not exist

---
 viper.go      | 20 ++++++++++++++++++--
 viper_test.go | 20 ++++++++++++++++++++
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/viper.go b/viper.go
index 0699c4c..9eb9f84 100644
--- a/viper.go
+++ b/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)
 }
diff --git a/viper_test.go b/viper_test.go
index c40c971..e940491 100644
--- a/viper_test.go
+++ b/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