add documentation for local development setup

Author: achempion

README.md

@@ -34,6 +34,7 @@ Browse the readme below, or jump to [a full example](#full-example).
   - [URL Generation](#url-generation)
     - [Alternate S3 configuration example](#alternate-s3-configuration-example)
 - [Full example](#full-example)
+- [Development](/documentation/development.md)
 
 ## Installation
 

docker-compose.yml

@@ -0,0 +1,9 @@
+version: "2.4"
+services:
+  waffle:
+    build:
+      context: .
+      dockerfile: Dockerfile.codeship
+    command: tail -f /dev/null
+    volumes:
+      - .:/srv/app:cached

documentation/development.md

@@ -0,0 +1,38 @@
+# Development
+
+Development documentation with instructions how to setup the project for local development.
+
+## Preliminary
+
+* Docker
+
+```sh
+# screen 1
+$ docker-compose up
+
+# screen 2
+$ docker-compose exec waffle sh
+$ > mix deps.get
+```
+
+## Run tests
+
+### Tests without S3 integration
+```sh
+$ mix test
+```
+
+### Tests with S3 integration
+
+AWS S3 setup
+- create a new user with FullS3Access
+- copy `key_id` and `secret`
+- create a new backet with *public access*
+- comment the `s3` exlusion inside `test/test_helper.exs`
+
+```sh
+$ export WAFFLE_TEST_BUCKET=
+$ export WAFFLE_TEST_S3_KEY=
+$ export WAFFLE_TEST_S3_SECRET=
+$ mix test
+```