add start script test
ADD
tests/venv/start/postBuild/README.rst
+System - Post-build scripts
+---------------------------
+
+It is possible to run scripts after you've built the environment specified in
+your other files. This could be used to, for example, download data or run
+some configuration scripts.
+
+In this example, we download and install a Jupyter Notebook extension.

ADD
tests/venv/start/postBuild/postBuild
+#!/bin/bash
+jupyter nbextension enable --py --sys-prefix ipyleaflet

ADD
tests/venv/start/postBuild/requirements.txt
+ipyleaflet

ADD
tests/venv/start/postBuild/start
+#!/bin/bash
+
+export TEST_START_VAR="var is set"
+
+exec "$@"

ADD
tests/venv/start/postBuild/verify
+#!/bin/bash
+set -euo pipefail
+jupyter nbextension list | grep 'jupyter-leaflet' | grep enabled
+
+if [ "$TEST_START_VAR" != "var is set" ]
+then
+ echo "TEST_START_VAR is not set"
+ exit 1
+fi

add start script test