Add a very simple test.

Makefile

@@ -7,7 +7,7 @@ build:
 dev: lint test build
 
 test:
-	go test -coverprofile=coverage.out
+	@go test -coverprofile=coverage.out ./...
 
 coverprofile_func:
 	go tool cover -func=coverage.out

cmd/headscale/headscale.go

@@ -249,11 +249,16 @@ var createPreAuthKeyCmd = &cobra.Command{
 	},
 }
 
-func main() {
+func loadConfig(path string) {
 	viper.SetConfigName("config")
+	if path == "" {
 		viper.AddConfigPath("/etc/headscale/")
 		viper.AddConfigPath("$HOME/.headscale")
 		viper.AddConfigPath(".")
+	} else {
+		// For testing
+		viper.AddConfigPath(path)
+	}
 	viper.AutomaticEnv()
 
 	viper.SetDefault("tls_letsencrypt_cache_dir", "/var/www/.cache")
@@ -279,6 +284,10 @@ func main() {
 	if !strings.HasPrefix(viper.GetString("server_url"), "http://") && !strings.HasPrefix(viper.GetString("server_url"), "https://") {
 		log.Fatalf("Fatal config error: server_url must start with https:// or http://")
 	}
+}
+
+func main() {
+	loadConfig("")
 
 	headscaleCmd.AddCommand(versionCmd)
 	headscaleCmd.AddCommand(serveCmd)
@@ -302,7 +311,6 @@ func main() {
 		fmt.Println(err)
 		os.Exit(-1)
 	}
-
 }
 
 func absPath(path string) string {

cmd/headscale/headscale_test.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/spf13/viper"
+	"gopkg.in/check.v1"
+)
+
+func Test(t *testing.T) {
+	check.TestingT(t)
+}
+
+var _ = check.Suite(&Suite{})
+
+type Suite struct{}
+
+func (s *Suite) SetUpSuite(c *check.C) {
+}
+
+func (s *Suite) TearDownSuite(c *check.C) {
+
+}
+
+func (*Suite) TestConfigLoading(c *check.C) {
+	tmpDir, err := ioutil.TempDir("", "headscale")
+	if err != nil {
+		c.Fatal(err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	path, err := os.Getwd()
+	if err != nil {
+		c.Fatal(err)
+	}
+
+	// Symlink the example config file
+	err = os.Symlink(filepath.Clean(path+"/../../config.json.example"), filepath.Join(tmpDir, "config.json"))
+	if err != nil {
+		c.Fatal(err)
+	}
+
+	// Load config
+	loadConfig(tmpDir)
+
+	// Test that config file was interpreted correctly
+	c.Assert(viper.GetString("server_url"), check.Equals, "http://192.168.1.12:8000")
+	c.Assert(viper.GetString("listen_addr"), check.Equals, "0.0.0.0:8000")
+	c.Assert(viper.GetString("derp_map_path"), check.Equals, "derp.yaml")
+	c.Assert(viper.GetString("db_port"), check.Equals, "5432")
+	c.Assert(viper.GetString("tls_letsencrypt_hostname"), check.Equals, "")
+	c.Assert(viper.GetString("tls_letsencrypt_challenge_type"), check.Equals, "HTTP-01")
+}