common: add user provider interface

Like 'FileSystem' and 'CommandExecutor', 'UserProvider' wraps functionality
related to the system users in a mockable interface. At the moment, its only
function returns the current user, eventually to be used for web server
daemon process setup.

Signed-off-by: Victoria Dye <[email protected]>

Author: vdye

internal/common/user.go

@@ -0,0 +1,19 @@
+package common
+
+import (
+	"os/user"
+)
+
+type UserProvider interface {
+	CurrentUser() (*user.User, error)
+}
+
+type userProvider struct{}
+
+func NewUserProvider() *userProvider {
+	return &userProvider{}
+}
+
+func (u *userProvider) CurrentUser() (*user.User, error) {
+	return user.Current()
+}