Add beginning setup for tests

README.md

@@ -8,6 +8,16 @@
 
 Visit `localhost:8080` to view.
 
+## Run a test
+
+You need chrome and chromedriver installed. The Dockerfile builds an image that does that. Then run the test with that image.
+
+`--network host` gives the container internet access. Necessary if tests make outside requests.
+
+    docker run --rm -it -v $PWD:/usr/src/app --network host btroops node google_test
+
+TODO add firefox and geckodriver
+
 ## Rough way to save the SVG map generated by JavaScript client-side
 
     const XMLS = new XMLSerializer();