pull the token module at runtime, not compile time

.gitignore

@@ -6,3 +6,4 @@ erl_crash.dump
 *.ez
 /config/*credentials*
 !/config/test-credentials.json
+.elixir_ls/

lib/kane/client.ex

@@ -2,37 +2,39 @@ defmodule Kane.Client do
   alias Response.Success
   alias Response.Error
 
-  @token_mod Application.get_env(:kane, :token, Goth.Token)
-
-  @spec get(binary) :: Success.t | Error.t
+  @spec get(binary) :: Success.t() | Error.t()
   def get(path), do: call(:get, path)
 
-  @spec put(binary, any) :: Success.t | Error.t
+  @spec put(binary, any) :: Success.t() | Error.t()
   def put(path, data \\ ""), do: call(:put, path, data)
 
-  @spec post(binary, any) :: Success.t | Error.t
+  @spec post(binary, any) :: Success.t() | Error.t()
   def post(path, data), do: call(:post, path, data)
 
-  @spec delete(binary) :: Success.t | Error.t
+  @spec delete(binary) :: Success.t() | Error.t()
   def delete(path), do: call(:delete, path)
 
   defp call(method, path) do
     headers = [auth_header()]
+
     apply(HTTPoison, method, [url(path), headers])
     |> handle_response
   end
+
   defp call(method, path, data) do
     headers = [auth_header(), {"content-type", "application/json"}]
+
     apply(HTTPoison, method, [url(path), encode!(data), headers])
     |> handle_response
   end
 
   defp url(path), do: Path.join([endpoint(), path])
 
   defp endpoint, do: Application.get_env(:kane, :endpoint, "https://pubsub.googleapis.com/v1")
+  defp token_mod, do: Application.get_env(:kane, :token, Goth.Token)
 
   defp auth_header do
-    {:ok, token} = @token_mod.for_scope(Kane.oauth_scope())
+    {:ok, token} = token_mod().for_scope(Kane.oauth_scope())
     {"Authorization", "#{token.type} #{token.token}"}
   end
 
@@ -43,6 +45,7 @@ defmodule Kane.Client do
     case response.status_code do
       code when code in 200..299 ->
         {:ok, response.body, code}
+
       err ->
         {:error, response.body, err}
     end