fix: isolate precommit steps with cmd, split test alias from DB setup

- Move ecto.create/ecto.migrate from test alias to test.setup
- Use cmd MIX_ENV=test in precommit to isolate each step in a fresh process
- Move Mox.defmock from test_helper.exs to valkey_test.exs

mix.exs

@@ -150,7 +150,8 @@ defmodule Microwaveprop.MixProject do
       "deps.get": ["deps.get", &apply_dep_patches/1],
       "ecto.setup": ["ecto.create", "ecto.migrate", "run priv/repo/seeds.exs"],
       "ecto.reset": ["ecto.drop", "ecto.setup"],
-      test: ["ecto.create --quiet", "ecto.migrate --quiet", "test"],
+      "test.setup": ["ecto.create --quiet", "ecto.migrate --quiet"],
+      test: ["test"],
       "assets.setup": ["tailwind.install --if-missing", "esbuild.install --if-missing"],
       "assets.build": [
         "compile",
@@ -164,7 +165,12 @@ defmodule Microwaveprop.MixProject do
         &copy_leaflet_images/1,
         "phx.digest"
       ],
-      precommit: ["compile", "deps.unlock --check-unused", "format", "credo --strict", "test"]
+      precommit: [
+        "format --check-formatted",
+        "cmd MIX_ENV=test mix test",
+        "deps.unlock --check-unused",
+        "cmd MIX_ENV=test mix credo --strict"
+      ]
     ]
   end
 

test/microwaveprop/valkey_test.exs

@@ -8,12 +8,16 @@ defmodule Microwaveprop.ValkeyTest do
 
   import Mox
 
+  # Defined here (not in test_helper.exs) so test_helper can load even
+  # when the precommit chain has purged Mox from the code path.
   alias Microwaveprop.Valkey
-  # Register Mox mock as the adapter and fake a Redix connection so
-  # configured?() returns true, letting command/pipeline run through the mock.
   alias Microwaveprop.Valkey.Conn
   alias Microwaveprop.Valkey.MockAdapter
 
+  Mox.defmock(MockAdapter, for: Microwaveprop.Valkey.Adapter)
+
+  # Register Mox mock as the adapter and fake a Redix connection so
+  # configured?() returns true, letting command/pipeline run through the mock.
   setup do
     prev_url = Application.get_env(:microwaveprop, :valkey_url)
     prev_adapter = Application.get_env(:microwaveprop, :valkey_adapter)