tests: standardize file structure & naming

test/test_default-host/test_default-host.py

@@ -0,0 +1,4 @@
+def test_fallback_on_default(docker_compose, nginxproxy):
+    r = nginxproxy.get("http://unknown.nginx-proxy.tld/port")
+    assert r.status_code == 200
+    assert r.text == "answer from port 81\n"

test/test_default-host/test_default-host.yml

@@ -0,0 +1,17 @@
+services:
+  # GIVEN a webserver with VIRTUAL_HOST set to web1.tld
+  web1:
+    image: web
+    expose:
+      - "81"
+    environment:
+      WEB_PORTS: 81
+      VIRTUAL_HOST: web1.tld
+
+  # WHEN nginx-proxy runs with DEFAULT_HOST set to web1.tld
+  sut:
+    image: nginxproxy/nginx-proxy:test
+    volumes:
+      - /var/run/docker.sock:/tmp/docker.sock:ro
+    environment:
+      DEFAULT_HOST: web1.tld