move more functions to infra for better testability

src/main/mastodon_bot/infra.cljs

@@ -1,4 +1,7 @@
-(ns mastodon-bot.infra)
+(ns mastodon-bot.infra
+  (:require
+   [cljs.reader :as edn]
+   ["fs" :as fs]))
 
 (defn js->edn [data]
   (js->clj data :keywordize-keys true))
@@ -6,3 +9,14 @@
 (defn exit-with-error [error]
   (js/console.error error)
   (js/process.exit 1))
+
+(defn find-config []
+  (let [config (or (first *command-line-args*)
+                   (-> js/process .-env .-MASTODON_BOT_CONFIG)
+                   "config.edn")]
+    (if (fs/existsSync config)
+      config
+      (exit-with-error (str "failed to read config: " config)))))
+
+(defn load-config []
+  (-> (find-config) (fs/readFileSync #js {:encoding "UTF-8"}) edn/read-string))