Improve developer experience (#10)

* chore: add makefile and Dockerfile
to be able to install dependencies and run tests

* chore: update travis configuration
to add a matrix and test with lowest and highest dependencies

.travis.yml

@@ -3,6 +3,16 @@ php:
     - '7.1'
     - '7.2'
 
-install: composer install
+env:
+    matrix:
+        - PREFER_LOWEST="--prefer-lowest"
+        - PREFER_LOWEST=""
+
+matrix:
+    allow_failures:
+        - env: PREFER_LOWEST="--prefer-lowest"
+
+install:
+    composer update $PREFER_LOWEST
 
 script: composer test

Dockerfile

@@ -0,0 +1,5 @@
+FROM php:7.1-alpine
+
+COPY --from=composer /usr/bin/composer /usr/bin/composer
+
+WORKDIR /app

Makefile

@@ -0,0 +1,15 @@
+.DEFAULT_GOAL:help
+
+RUN?=docker run --rm --interactive --tty --volume ${PWD}:/app woohoolabs-yin-bundle
+
+help:
+	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m * make %s\033[0m ## %s\n", $$1, $$2}'
+
+build: ## Build image used to install dependencies and run tests
+	docker build --tag=woohoolabs-yin-bundle ${PWD}
+
+install: ## Install dependencies with docker
+	$(RUN) composer install
+
+test: ## Run phpspec tests
+	$(RUN) vendor/bin/phpspec run