Add script for running test with Postgres

with-db.sh

@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+
+# * Run a postgres server at localhost:${DB_PORT}
+# * Wait for it to be up and running
+# * Run the passed arguments as a command
+# * Kill the postgres server
+#
+# Example usage: ./with-db.sh cabal test
+#
+# The application running in this context can use
+# the DB_* variables to connect to postgres.
+export DB_USER=opium
+export DB_PASS=opium
+export DB_NAME=opium
+export DB_PORT=5442
+
+# On error or exit: Kill the postgres container
+function kill_db_container {
+  docker kill "${CONTAINER_ID}" > /dev/null
+}
+trap kill_db_container EXIT
+
+CONTAINER_ID=$(docker run --rm \
+  -e "POSTGRES_USER=${DB_USER}" \
+  -e "POSTGRES_PASSWORD=${DB_PASS}" \
+  -e "POSTGRES_DB=${DB_NAME}" \
+  -p "127.0.0.1:${DB_PORT}:5432" \
+  --health-cmd pg_isready \
+  --health-interval 0.25s \
+  --detach \
+  postgres:14-alpine)
+
+# Setting --health-cmd above allows us to wait for postgres to be up
+until [[ "$(docker inspect -f "{{.State.Health.Status}}" "${CONTAINER_ID}" || true)" = healthy ]]
+do
+  sleep 0.1
+done
+
+"$@"