Update default postgres user for tests

.travis.yml

@@ -6,7 +6,6 @@ otp_release:
 elixir:
   - 1.11.1
 before_script:
-  - export SCRIVENER_ECTO_DB_USER=postgres
   - MIX_ENV=test mix db.reset
 script:
   - mix test

README.md

@@ -85,7 +85,7 @@ First, you'll need to build the test database.
 MIX_ENV=test mix db.reset
 ```
 
-This task assumes you have postgres installed and that your current user can create / drop databases. If you'd prefer to use a different user, you can specify it with the environment variable `SCRIVENER_ECTO_DB_USER`.
+This task assumes you have postgres installed and that the `postgres` user can create / drop databases. If you'd prefer to use a different user, you can specify it with the environment variable `SCRIVENER_ECTO_DB_USER`.
 
 With the database built, you can now run the tests.
 

config/test.exs

@@ -6,6 +6,6 @@ config :scrivener_ecto, Scrivener.Ecto.Repo,
   adapter: Ecto.Adapters.Postgres,
   pool: Ecto.Adapters.SQL.Sandbox,
   database: "scrivener_test",
-  username: System.get_env("SCRIVENER_ECTO_DB_USER") || System.get_env("USER")
+  username: System.get_env("SCRIVENER_ECTO_DB_USER") || "postgres"
 
 config :logger, :console, level: :error

docker-compose.yaml

@@ -5,5 +5,4 @@ services:
     ports:
       - "127.0.0.1:5432:5432"
     environment:
-      - POSTGRES_USER=${USER}
       - POSTGRES_HOST_AUTH_METHOD=trust