add test suite. See #197

This test suite is implemented using [bats](https://github.com/sstephenson/bats).

Not all features are tested. For instance ssl features and custom nginx config are missing. Probably others.

This test suite won't work with TravisCI. Too many evenings were wasted trying to overcome [issues](http://stackoverflow.com/questions/32846800/travis-fails-to-stop-docker-containers) that arises only on the TravisCI platform. However it runs on [CircleCI](https://circleci.com) which is also free for opensource projects.

test/default-host.bats

@@ -0,0 +1,38 @@
+#!/usr/bin/env bats
+load test_helpers
+
+function setup {
+	# make sure to stop any web container before each test so we don't
+	# have any unexpected contaiener running with VIRTUAL_HOST or VIRUTAL_PORT set
+	docker ps -q --filter "label=bats-type=web" | xargs -r docker stop >&2
+}
+
+
+@test "[$TEST_FILE] DEFAULT_HOST=web1.bats" {
+	SUT_CONTAINER=bats-nginx-proxy-${TEST_FILE}-1
+
+	# GIVEN a webserver with VIRTUAL_HOST set to web.bats
+	docker_clean bats-web
+	run docker run -d \
+		--label bats-type="web" \
+		--name bats-web \
+		-e VIRTUAL_HOST=web.bats \
+		--expose 80 \
+		-w /var/www \
+		python:3 \
+		python -m http.server 80
+	assert_success
+
+	# WHEN nginx-proxy runs with DEFAULT_HOST set to web.bats
+	run nginxproxy $SUT_CONTAINER -v /var/run/docker.sock:/tmp/docker.sock:ro -e DEFAULT_HOST=web.bats
+	assert_success
+	docker_wait_for_log $SUT_CONTAINER 3 "Watching docker events"
+
+	# THEN querying the proxy without Host header → 200
+	run curl_container $SUT_CONTAINER / --head
+	assert_output -l 0 $'HTTP/1.1 200 OK\r'
+
+	# THEN querying the proxy with any other Host header → 200
+	run curl_container $SUT_CONTAINER / --head --header "Host: something.I.just.made.up"
+	assert_output -l 0 $'HTTP/1.1 200 OK\r'
+}