feat(example): Allow configuring some parameters with env variables

example/server/config/config_test.go

@@ -0,0 +1,77 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"testing"
+)
+
+func TestFromEnvVars(t *testing.T) {
+
+	for _, tc := range []struct {
+		name     string
+		env      map[string]string
+		defaults *Config
+		want     *Config
+	}{
+		{
+			name: "no vars, no default values",
+			env:  map[string]string{},
+			want: &Config{},
+		},
+		{
+			name: "no vars, only defaults",
+			env:  map[string]string{},
+			defaults: &Config{
+				Port:        "6666",
+				UsersFile:   "/default/user/path",
+				RedirectURI: []string{"re", "direct", "uris"},
+			},
+			want: &Config{
+				Port:        "6666",
+				UsersFile:   "/default/user/path",
+				RedirectURI: []string{"re", "direct", "uris"},
+			},
+		},
+		{
+			name: "overriding default values",
+			env: map[string]string{
+				"PORT":         "1234",
+				"USERS_FILE":   "/path/to/users",
+				"REDIRECT_URI": "http://redirect/redirect",
+			},
+			defaults: &Config{
+				Port:        "6666",
+				UsersFile:   "/default/user/path",
+				RedirectURI: []string{"re", "direct", "uris"},
+			},
+			want: &Config{
+				Port:        "1234",
+				UsersFile:   "/path/to/users",
+				RedirectURI: []string{"http://redirect/redirect"},
+			},
+		},
+		{
+			name: "multiple redirect uris",
+			env: map[string]string{
+				"REDIRECT_URI": "http://host_1,http://host_2,http://host_3",
+			},
+			want: &Config{
+				RedirectURI: []string{
+					"http://host_1", "http://host_2", "http://host_3",
+				},
+			},
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			os.Clearenv()
+			for k, v := range tc.env {
+				os.Setenv(k, v)
+			}
+			cfg := FromEnvVars(tc.defaults)
+			if fmt.Sprint(cfg) != fmt.Sprint(tc.want) {
+				t.Errorf("Expected FromEnvVars()=%q, but got %q", tc.want, cfg)
+			}
+		})
+	}
+}