tests: adds integration test for rooster add

tests/test-command-add.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+# create a new empty volume for tests
+docker volume rm rooster >& /dev/null
+docker volume create rooster >& /dev/null
+
+# create the file
+printf 'y\nxxxx\nabcd\n' | docker run --rm -i -v rooster:/home/rooster rooster add -s YouTube test@example.com || exit 1
+
+# change password
+printf 'xxxx\n' | docker run --rm -i -v rooster:/home/rooster rooster get -s youtube 2>&1 | grep abcd || exit 1