From 5619c0edbec91139df79dd0d0d8d4967f4646a08 Mon Sep 17 00:00:00 2001
From: Roland Schilter <roli@schilter.me>
Date: Fri, 5 Aug 2016 09:18:19 +0200
Subject: [PATCH] Reset cache on config name change

I stumbled over this when trying to merge multiple configs.

```
viper.SetConfigName("default")
err := viper.MergeInConfig()
```
which caches file path resolvemenet in `v.configFile`

and then
```
viper.SetConfigName("prod")
err := viper.MergeInConfig()
```

which reuses `v.configFile` without updating it accordingly to the new name.

See https://github.com/spf13/viper/blob/c1ccc378a054ea8d4e38d8c67f6938d4760b53dd/viper.go#L1240
---
 viper.go      | 1 +
 viper_test.go | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/viper.go b/viper.go
index e5a360a..d800395 100644
--- a/viper.go
+++ b/viper.go
@@ -1214,6 +1214,7 @@ func SetConfigName(in string) { v.SetConfigName(in) }
 func (v *Viper) SetConfigName(in string) {
 	if in != "" {
 		v.configName = in
+		v.configFile = ""
 	}
 }
 
diff --git a/viper_test.go b/viper_test.go
index aa9d7fe..0c0c7e5 100644
--- a/viper_test.go
+++ b/viper_test.go
@@ -901,3 +901,9 @@ func TestUnmarshalingWithAliases(t *testing.T) {
 
 	assert.Equal(t, &C, &config{Id: 1, FirstName: "Steve", Surname: "Owen"})
 }
+
+func TestSetConfigNameClearsFileCache(t *testing.T) {
+	SetConfigFile("/tmp/config.yaml")
+	SetConfigName("default")
+	assert.Empty(t, v.getConfigFile())
+}