Add a small document on testing

README.md

@@ -42,6 +42,7 @@ and in README files for individual Ansible roles:
 * [Service discovery protocol](docs/service_mesh.md)
 * [HTTP router](docs/http_router.md)
 * [Docker usage](roles/docker/README.md)
+* [Testing](docs/testing.md)
 
 ### Built-in services documentation
 

docs/testing.md

+Testing
+===
+
+This repository contains some integration tests that use Vagrant to
+spin up virtual machines and run Ansible against them. The virtual
+machines will be destroyed and re-created every time the tests run, so
+it would be a good idea to use a local caching proxy for Debian
+packages (such as *apt-cacher-ng*).
+
+## Networking
+
+The virtual machines used in tests make use of the 192.168.10.0/24
+network. If it is already in use by your local environment, you're
+going to have trouble unfortunately. On this network, the local (host)
+machine will have the address 192.168.10.1.
+
+## Running tests
+
+To run a test, go to the *test* subdirectory of this repository, and
+run the *run-test.sh* command, with the name of the subdirectory
+containing the test environment:
+
+```
+cd test
+./run-test.sh --apt-proxy 192.168.10.1:3142 test-base
+```
+