add docker-compose to manage test db

Author: fahchen

README.md

@@ -252,8 +252,13 @@ Catelog.roots() |> Repo.all
 ## Contributing
 First, set appropriate settings for test database.
 ```shell
-export POSTGRES_USER=test_username POSTGRES_PASSWORD=test_password MIX_ENV=test
+export POSTGRES_USER=postgres POSTGRES_PASSWORD=postgres MIX_ENV=test
+
+docker-compose up
+
+mix do ecto.create, ecto.migrate
 ```
+
 run test.
 ```elixir
 mix test

config/test.exs

@@ -5,8 +5,8 @@ config :hierarch, ecto_repos: [Dummy.Repo]
 
 config :hierarch, Dummy.Repo,
   adapter: Ecto.Adapters.Postgres,
-  username: System.get_env("POSTGRES_USER") || "postgres",
-  password: System.get_env("POSTGRES_PASSWORD") || "posgtres",
+  username: System.get_env("POSTGRES_USER", "postgres"),
+  password: System.get_env("POSTGRES_PASSWORD", "postgres"),
   database: "hierarch_test",
   hostname: "localhost",
   pool: Ecto.Adapters.SQL.Sandbox,

docker-compose.yml

@@ -0,0 +1,11 @@
+version: '3'
+
+services:
+  db:
+    image: postgres:9.5-alpine
+    environment:
+      POSTGRES_USER: postgres
+      POSTGRES_PASSWORD: postgres
+      POSTGRES_DB: hierarch_test
+    ports:
+      - 5432:5432