test: docker-gen network segregation

* fix tests
* remove obsolete compose version

test/test_dockergen/test_dockergen_network_segregation.py

@@ -0,0 +1,27 @@
+import docker
+import pytest
+from packaging.version import Version
+
+
+raw_version = docker.from_env().version()["Version"]
+pytestmark = pytest.mark.skipif(
+    Version(raw_version) < Version("1.13"),
+    reason="Docker compose syntax v3 requires docker engine v1.13 or later (got {raw_version})"
+)
+
+
+def test_unknown_virtual_host_is_503(docker_compose, nginxproxy):
+    r = nginxproxy.get("http://unknown.nginx.container.docker/")
+    assert r.status_code == 503
+
+
+def test_forwards_to_whoami(docker_compose, nginxproxy):
+    r = nginxproxy.get("http://whoami2.nginx.container.docker/")
+    assert r.status_code == 200
+    whoami_container = docker_compose.containers.get("whoami2")
+    assert r.text == f"I'm {whoami_container.id[:12]}\n"
+
+
+if __name__ == "__main__":
+    import doctest
+    doctest.testmod()