From 7bca6f6bd87b01437b546795b6375eee41730c46 Mon Sep 17 00:00:00 2001
From: Nathan Guerin <nathan.guerin@goeuro.com>
Date: Thu, 3 Jul 2014 00:09:22 +0200
Subject: [PATCH] Allow driver to be set from environment variable

This changeset support for allowing the database driver to
be set from an environment variable. Added a unit test to confirm
behavior.  Resolves #31
---
 db-sample/dbconf.yml     |  4 ++++
 lib/goose/dbconf.go      |  1 +
 lib/goose/dbconf_test.go | 35 ++++++++++++++++++++++++++++++++++-
 3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/db-sample/dbconf.yml b/db-sample/dbconf.yml
index 65672fc..b820527 100644
--- a/db-sample/dbconf.yml
+++ b/db-sample/dbconf.yml
@@ -16,3 +16,7 @@ customimport:
     open: customdriver open
     import: github.com/custom/driver
     dialect: mysql
+
+environment_variable_config:
+    driver: $DB_DRIVER
+    open: $DATABASE_URL
diff --git a/lib/goose/dbconf.go b/lib/goose/dbconf.go
index accf219..8dc1a8c 100644
--- a/lib/goose/dbconf.go
+++ b/lib/goose/dbconf.go
@@ -41,6 +41,7 @@ func NewDBConf(p, env string, pgschema string) (*DBConf, error) {
 	if err != nil {
 		return nil, err
 	}
+	drv = os.ExpandEnv(drv)
 
 	open, err := f.Get(fmt.Sprintf("%s.open", env))
 	if err != nil {
diff --git a/lib/goose/dbconf_test.go b/lib/goose/dbconf_test.go
index b6f0886..37828ae 100644
--- a/lib/goose/dbconf_test.go
+++ b/lib/goose/dbconf_test.go
@@ -1,7 +1,8 @@
 package goose
 
 import (
-	// "fmt"
+	"os"
+	"reflect"
 	"testing"
 )
 
@@ -35,3 +36,35 @@ func TestImportOverride(t *testing.T) {
 		t.Errorf("bad custom import. got %v want %v", got, want)
 	}
 }
+
+func TestDriverSetFromEnvironmentVariable(t *testing.T) {
+
+	databaseUrlEnvVariableKey := "DB_DRIVER"
+	databaseUrlEnvVariableVal := "sqlite3"
+	databaseOpenStringKey := "DATABASE_URL"
+	databaseOpenStringVal := "db.db"
+
+	os.Setenv(databaseUrlEnvVariableKey, databaseUrlEnvVariableVal)
+	os.Setenv(databaseOpenStringKey, databaseOpenStringVal)
+
+	dbconf, err := NewDBConf("../../db-sample", "environment_variable_config", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	got := reflect.TypeOf(dbconf.Driver.Dialect)
+	want := reflect.TypeOf(&Sqlite3Dialect{})
+
+	if got != want {
+		t.Errorf("Not able to read the driver type from environment variable."+
+			"got %v want %v", got, want)
+	}
+
+	gotOpenString := dbconf.Driver.OpenStr
+	wantOpenString := databaseOpenStringVal
+
+	if gotOpenString != wantOpenString {
+		t.Errorf("Not able to read the open string from the environment."+
+			"got %v want %v", gotOpenString, wantOpenString)
+	}
+}