Add test watcher.

mix.exs

@@ -52,7 +52,8 @@ defmodule TwentyFortyEight.MixProject do
       {:dns_cluster, "~> 0.1.1"},
       {:plug_cowboy, "~> 2.5"},
       {:credo, "~> 1.7", only: [:dev, :test], runtime: false},
-      {:dialyxir, "~> 1.4", only: [:dev, :test], runtime: false}
+      {:dialyxir, "~> 1.4", only: [:dev, :test], runtime: false},
+      {:mix_test_watch, "~> 1.0", only: [:dev, :test], runtime: false}
     ]
   end
 

mix.lock

@@ -22,6 +22,7 @@
   "jason": {:hex, :jason, "1.4.1", "af1504e35f629ddcdd6addb3513c3853991f694921b1b9368b0bd32beb9f1b63", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "fbb01ecdfd565b56261302f7e1fcc27c4fb8f32d56eab74db621fc154604a7a1"},
   "mime": {:hex, :mime, "2.0.5", "dc34c8efd439abe6ae0343edbb8556f4d63f178594894720607772a041b04b02", [:mix], [], "hexpm", "da0d64a365c45bc9935cc5c8a7fc5e49a0e0f9932a761c55d6c52b142780a05c"},
   "mint": {:hex, :mint, "1.5.1", "8db5239e56738552d85af398798c80648db0e90f343c8469f6c6d8898944fb6f", [:mix], [{:castore, "~> 0.1.0 or ~> 1.0", [hex: :castore, repo: "hexpm", optional: true]}, {:hpax, "~> 0.1.1", [hex: :hpax, repo: "hexpm", optional: false]}], "hexpm", "4a63e1e76a7c3956abd2c72f370a0d0aecddc3976dea5c27eccbecfa5e7d5b1e"},
+  "mix_test_watch": {:hex, :mix_test_watch, "1.1.1", "eee6fc570d77ad6851c7bc08de420a47fd1e449ef5ccfa6a77ef68b72e7e51ad", [:mix], [{:file_system, "~> 0.2.1 or ~> 0.3", [hex: :file_system, repo: "hexpm", optional: false]}], "hexpm", "f82262b54dee533467021723892e15c3267349849f1f737526523ecba4e6baae"},
   "nimble_options": {:hex, :nimble_options, "1.0.2", "92098a74df0072ff37d0c12ace58574d26880e522c22801437151a159392270e", [:mix], [], "hexpm", "fd12a8db2021036ce12a309f26f564ec367373265b53e25403f0ee697380f1b8"},
   "nimble_pool": {:hex, :nimble_pool, "1.0.0", "5eb82705d138f4dd4423f69ceb19ac667b3b492ae570c9f5c900bb3d2f50a847", [:mix], [], "hexpm", "80be3b882d2d351882256087078e1b1952a28bf98d0a287be87e4a24a710b67a"},
   "phoenix": {:hex, :phoenix, "1.7.9", "9a2b873e2cb3955efdd18ad050f1818af097fa3f5fc3a6aaba666da36bdd3f02", [:mix], [{:castore, ">= 0.0.0", [hex: :castore, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:phoenix_pubsub, "~> 2.1", [hex: :phoenix_pubsub, repo: "hexpm", optional: false]}, {:phoenix_template, "~> 1.0", [hex: :phoenix_template, repo: "hexpm", optional: false]}, {:phoenix_view, "~> 2.0", [hex: :phoenix_view, repo: "hexpm", optional: true]}, {:plug, "~> 1.14", [hex: :plug, repo: "hexpm", optional: false]}, {:plug_cowboy, "~> 2.6", [hex: :plug_cowboy, repo: "hexpm", optional: true]}, {:plug_crypto, "~> 1.2 or ~> 2.0", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}, {:websock_adapter, "~> 0.5.3", [hex: :websock_adapter, repo: "hexpm", optional: false]}], "hexpm", "83e32da028272b4bfd076c61a964e6d2b9d988378df2f1276a0ed21b13b5e997"},