Add simple vanilla-emacs test ground

core/debug.el

@@ -0,0 +1,17 @@
+;;; debug.el -*- lexical-binding: t; no-byte-compile: t; -*-
+
+;; load me after running Emacs -Q:
+;;
+;;   (load-file (concat user-emacs-directory "core/debug.el"))
+;;
+;; then you can test packages in isolation.
+
+(setq user-emacs-directory (expand-file-name "../" (file-name-directory load-file-name))
+      package--init-file-ensured t
+      package-user-dir (expand-file-name ".local/packages/elpa" user-emacs-directory)
+      package-archives
+      '(("gnu"   . "https://elpa.gnu.org/packages/")
+        ("melpa" . "https://melpa.org/packages/")
+        ("org"   . "https://orgmode.org/elpa/")))
+
+(package-initialize)

init.el

@@ -28,3 +28,10 @@
 ;;; License: MIT
 
 (require 'core (concat user-emacs-directory "core/core"))
+
+;; To test something in a blank, vanilla Emacs session (Emacs -Q) comment the
+;; require above and load core/debug.el instead:
+;;
+;; (load (concat user-emacs-directory "core/debug.el"))
+;;
+;; <-- place debug code here -->